CN1868720B - injection molding machine - Google Patents

Abstract

An injection molding machine comprising: a cartridge member; an injection member disposed in the cartridge member so that the injection member can advance and retreat; an injection motor; and a motion direction changing part for transmitting the rotational motion of the injection motor and converting the rotational motion into a linear motion; a drive force transmission mechanism for restricting the relative movement of the injection member in the axial direction with respect to the drive shaft while allowing the relative movement in the rotational direction; the injection motor and the movement direction changing member are disposed on the same axis.

Description

injection molding machine

This application is a divisional application filed on April 28, 1999 with the title of invention "injection molding machine" and application number 02124384.0.

technical field

The present invention relates to an injection molding machine.

Background technique

Typically, in an injection molding machine, resin heated and melted in a heated cylinder is injected under high pressure into a mold set, thereby filling the cavity with resin. Next, the molten resin is cooled and solidified to obtain a molded article.

To accomplish this molding operation, an injection molding machine includes a clamping device and an injection device. There is a fixed template and a moving template in the clamping device. The movable platen advances and retreats under the drive of a clamping oil cylinder, so as to realize mold clamping, mold clamping and mold opening.

The injection device includes a heating cylinder for heating and melting resin supplied from a hopper, and an injection nozzle for injecting the molten resin. In addition, a screw is installed in the heating cylinder so that the screw can rotate and advance and retreat. The screw advances to inject the resin out of the injection nozzle and reverses to meter the resin.

In order to make the screw advance and retreat, a motor-driven injection device is installed.

Figure 1 is a schematic diagram of a conventional injection device.

In FIG. 1 , reference numeral 2 denotes an injection device, and 4 denotes a base frame of the injection device 2 . A heating cylinder 21 is fixedly mounted on the front end (left side in FIG. 1 ) of the base frame 4 , and an injection nozzle 21 a is mounted on the front end (left side in FIG. 1 ) of the heating cylinder 21 . A hopper 21b is installed on the heating cylinder 21, and a screw 20 is installed in the heating cylinder 21 so that the screw 20 can rotate and advance and retreat (moving leftward and rightward respectively in FIG. 1). The rear end (right side in FIG. 1 ) of the screw 20 is rotatably supported by a support member 5 .

A metering motor 6 with a speed reduction mechanism is installed on the support member 5 . The rotation of the metering motor 6 is transmitted to the screw 20 via a timing belt 7a.

Furthermore, a threaded shaft 8 parallel to the screw 20 is rotatably supported. The rear end of the threaded shaft 8 is connected with an injection motor 9 with a speed reduction mechanism through a timing belt 7b. That is to say, the injection motor 9 is used to drive the threaded shaft 8 to rotate. The front end of the threaded shaft 8 is engaged with a nut 5a fixed on the support member 5. As shown in FIG. In this way, when the injection motor 9 is started, the threaded shaft 8 can be rotated by the timing belt 7b, thereby driving the nut 5a to move axially.

In the injection device 2 having the above structure, at one metering stage, the metering motor 6 is activated to rotate the screw 20 via the timing belt 7a, thereby retreating the screw 20 by a predetermined distance (to the right in FIG. 1 ). At this time, the resin is supplied from the hopper 21b, is heated and melted in the heating cylinder 21, and gathers in front of the screw 20 as the screw 20 retreats.

Furthermore, during an injection phase, the injection motor 9 is activated to rotate the threaded shaft 8 via the timing belt 7b, so that the nut 5a and the support 5 move with the rotation of the threaded shaft 8 . As a result, the screw 20 advances (moves to the left in FIG. 1 ), and the resin collected in front of the screw 20 is injected from the injection nozzle 21a.

However, the injection device 2 has the following disadvantages. That is, in the injection device 2, the metering motor 6 and the injection motor 9 must be activated during the metering phase and the injection phase, respectively. In addition, the rotation of the metering motor 6 and the injection motor 9 are transmitted to the screw 20 through a reduction mechanism, a pulley, and the like. Therefore, the mechanical efficiency is relatively low and the inertia is relatively high. As a result, during the injection phase, a relatively long time and a relatively high torque are required to reach the initial injection speed and to change the injection speed. In addition, the time required from the injection phase to the dwell phase is relatively long.

In order to overcome the above disadvantages, there has been provided a built-in motor type injection device in which a screw, an injection motor and a metering motor are arranged on the same axis.

Fig. 2 is a sectional view of a conventional built-in motor type injection device.

In FIG. 2, reference numeral 12 denotes a heating cartridge, and an injection nozzle 12a is mounted on the front end of the heating cartridge 12 (left side in FIG. 2). A screw 22 is installed in the heating cylinder 12 such that the screw 22 can rotate and advance and retreat (move left and right in FIG. 2 ).

The screw 22 has a screw head 22a at its front end. The screw 22 extends rearward (rightward in FIG. 2 ) in the heating cylinder 12 and is connected to a first spline shaft 63 at its rear end (rightward end in FIG. 2 ).

Like this, in a metering stage, the screw rod 22 retreats with a predetermined distance (moves to the right in FIG. 2 ) and keeps rotating, and the powdery resin is then supplied from a hopper not shown, and is heated and melted in the heating cylinder 12 , and gather in front of the screw head 22a of the screw 22 (the left side in FIG. 2 ) along with the retreat of the screw 22 .

In addition, in an injection stage, when the screw 22 advances (moves to the left in FIG. 2), the resin gathered in front of the screw head 22a is injected from the injection nozzle 21a and filled into a cavity of an unillustrated mold device. .

A driving section casing 11 is fixed on the rear end of the heating cylinder 12 . A metering motor 44 is arranged on the front portion (left side part) of the driving section housing 11, and an injection motor 45 is arranged on the rear part (right side part) of the driving section housing 11, so the metering motor 44 and the injection motor 45 share a central axis . The metering motor 44 includes a stator 46 and a rotor 47 , while the injection motor 45 includes a stator 48 and a rotor 49 .

The motor 47 is supported by the drive section housing 11 and is rotatable relative to the latter. Specifically, a hollow first rotor shaft 56 is fixedly fitted in the rotor 47 , and the first rotor shaft 56 is supported by bearings 51 and 52 .

Likewise, the motor 49 is supported by the drive section housing 11 and is rotatable relative to the latter. Specifically, a hollow second rotor shaft 57 is fixedly fitted in the rotor 49 , and the second rotor shaft 57 is supported by bearings 53 and 54 .

The screw rod 22 can retreat under the drive of the metering motor 44 and keep rotating. In order to realize this movement, a first spline nut 62 is fixed on the front end of the first rotor shaft 56; a first spline shaft 63 engages the first spline nut 62 through splines; and the screw rod 22 is fixed on the first The front end of the spline shaft 63. In this way, when the rotor 47 is rotated by the metering motor 44 , the rotation of the rotor 47 will be transmitted to the screw 22 , thereby causing the screw 22 to rotate. At this time, the first spline shaft 63 retreats relative to the first spline nut 62 , thereby causing the screw rod 22 to retreat. It should be noted that when the screw 22 retreats, there will be back pressure applied to the screw 22 to resist the pressure generated by the resin.

In addition, the screw 22 can be driven forward by the injection motor 45 . To achieve this movement, an annular bearing retainer 64 is secured to the rear end of the second rotor shaft 57 ; a ball screw shaft 65 is inserted and secured to the bearing retainer 64 . The ball screw shaft 65 is supported by the drive section housing 11 so as to be rotatable relative to the latter. Specifically, the ball screw shaft 65 is supported on the drive section housing 11 via a bearing retainer 64 , a bearing 66 , and a bearing 67 disposed on the rear side of the bearing 66 .

A ball nut 69 is installed in the second rotor shaft 57 so that the ball nut 69 can advance and retreat, and the ball nut 69 is engaged with the ball screw shaft 65 . In this way, the rotation of the rotor 49 is transmitted to the ball screw shaft 65 via the second rotor shaft 57 and the bearing retainer 64 . The ball nut 69 and the ball screw shaft 65 convert the rotary motion into linear motion so that the ball nut 69 can advance and retreat.

In addition, in order to prevent the ball nut 69 from rotating together with the ball screw shaft 65, a hollow second spline shaft 71 is fixed on the front end of the ball nut 69, and the second spline shaft 71 engages with a shaft fixed on the drive section housing through a spline. 11 on the second spline nut 76.

A bearing housing 72 is fixed on the front end of the second spline shaft 71 . A thrust bearing 73 is installed in the bearing box 72 at the front side of the bearing box, and a bearing 74 is installed in the bearing box 72 at the rear side of the bearing box. Thus, the first spline shaft 63 is supported by the bearings 73 and 74 to be rotatable relative to the second spline shaft 71 and the ball nut 69 .

In the structure described above, the rotation of the metering motor 44 and the rotation of the injection motor 45 are transmitted to the screw 22 without adding a reduction mechanism, a pulley, or the like. Thus, mechanical efficiency is increased while inertia is reduced.

The driving section casing 11 is composed of a front cover 11a, a central case 11b and a rear cover 11c; the heating cylinder 12 is fixed to the front end of the front cover 11a.

The metering motor 44 is surrounded by a sleeve-shaped stator frame 46a, and the injection motor 45 is surrounded by a sleeve-shaped stator frame 48a. The front cover 11a and the center case 11b are connected together by threaded tie rods 46b, and the stator frame 46a is stacked between the front cover 11a and the center case 11b. Likewise, the central case 11b and the rear cover 11c are connected together by threaded tie rods 48b, and the stator frame 48a is stacked between the central case 11b and the rear cover 11c. The stator frame 48a is supported by the frictional force generated by the tightening of the tie rods 48b.

In the conventional injection apparatus described above, since the metering motor 44 and the injection motor 45 are arranged on the same axis, the axial length of the injection molding machine increases. And when trying to reduce the axial length of the injection molding machine, the outer diameters of the metering motor 44 and the injection motor 45 are increased, resulting in increased inertia.

In addition, when the injection motor 45 is activated to rotate the ball screw shaft 65 so that the resin is injected from the heating cylinder 12 as the screw advances, a reaction force corresponding to the injection force passes through the heating cylinder 12 and the front cover 11a. to the tie rod 46b, and from the rear cover 11c to the tie rod 48b. The tie rods 46b and 48b are thus elongated, resulting in a reduced locking force.

In the structure described above, when the metering motor 44 or the injection motor 45 is activated to rotate the rotor 47 or 49, the stator frames 46a and 48a may rotate. Therefore, the locking force of the tie rods 46b and 48b must be strictly controlled. This makes maintenance of injection molding machines very troublesome.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve the above-mentioned problems in conventional injection molding machines and to provide an injection molding machine whose mechanical efficiency is improved with reduced inertia, whose axial length is reduced, and which is easy to assemble and maintain.

Summary of the invention

To achieve the above object, an injection molding machine according to the present invention comprises: a barrel part; an injection part arranged in the barrel part so that the injection part can advance and retreat; an injection motor; and a transmission A shaft, which is connected to the injector, thereby enabling the drive shaft to rotate relative to the injector. The transmission shaft has a rotation transmission part for transmitting the rotation motion of the injection motor, and a motion conversion part for converting the rotation motion into linear motion.

The injection motor and the drive shaft are arranged on the same axis, and the drive shaft advances and retreats within the rotor of the injection motor.

In this case, since the rotational motion of the injection motor is directly transmitted to the drive shaft, no reduction mechanism, pulleys, and the like are added. Thus mechanical efficiency can be increased and inertia can be reduced. As a result, during the injection phase, the time required to establish and change the injection speed and the torque required to establish and change the injection speed can be reduced. In addition, the time required to switch from the injection phase to the packing phase is reduced.

Since the transmission shaft advances and retreats inside the rotor of the injection motor, the axial length of the injection molding machine can be reduced.

In another injection molding machine according to the present invention, the injection motor and drive shaft are arranged on the same axis as the injection part.

In another injection molding machine according to the present invention, the injection motor, the transmission shaft and the injection part are arranged on different axes from each other.

In another injection molding machine according to the invention, a metering motor is provided which is arranged on the same axis as the injection part.

In another injection molding machine according to the present invention, a metering motor is provided which is arranged on a different axis from the injection part and which is connected to the injection part through a transmission.

In another injection molding machine according to the present invention, the transmission shaft includes a ball screw shaft portion and a spline shaft portion.

The present invention also provides another injection molding machine, which includes: a heating cylinder; a screw, which is arranged in the heating cylinder, so that the screw can advance and retreat; an injection motor; and a transmission shaft, which is connected to the screw , so that the drive shaft can rotate relative to the screw. The transmission shaft has a rotation transmission part for transmitting the rotation motion of the injection motor, and a motion conversion part for converting the rotation motion into linear motion.

The injection motor and the drive shaft are arranged on the same axis, and the drive shaft advances and retreats within the rotor of the injection motor.

The present invention also provides another injection molding machine comprising: a hollow motor including a stator and a rotor; a stator frame surrounding the hollow motor and supporting the stator; and first and second plates , which are detachably attached to opposite ends of the upper stator frame.

In this case, the hollow motor can be replaced by separating the first and second plates from the stator frame.

Since the stator frame is interconnected with the first and second plates, the stator frame will not rotate after the hollow motor is started. In this way, there is no need to strictly control the locking force required to interconnect the stator frame with the first and second plates.

As a result, assembly and maintenance of the injection molding machine is facilitated.

In another injection molding machine according to the invention, a pulling force generated after the hollow motor is activated is transmitted to the stator frame.

In another injection molding machine according to the present invention, the stator frame has a cylindrical portion for supporting the stator, and flange portions formed at opposite ends of the cylindrical portion.

The present invention also provides another injection molding machine comprising: a hollow rotor shaft supported in a rotatable manner; a motor comprising a stator and a a rotor on the rotor shaft; and an injection piece which is positioned on the same axis as the motor.

When the injection member is at the rearward end of a stroke, the rear end of the injection member moves to a position behind the front end of the rotor shaft.

In this case, the injection piece can be superimposed with the metering motor when the injection piece advances or retreats. Therefore, the axial length of the injection molding machine can be reduced.

In another injection molding machine according to the present invention, a sleeve is fixed on the front end of the rotor shaft; a spline nut is fixed on the rear end of the sleeve; and a spline shaft is engaged with the spline nut by spline engagement The injection part is connected.

In this case, when the injection member is at the rearward end of its stroke, the rear end of the injection member may be located at a distance rearward from the front end of the rotor shaft equal to the length of the sleeve.

Brief description of the drawings

Fig. 1 is the schematic diagram of a traditional injection equipment;

Fig. 2 is a sectional view of a conventional built-in motor type injection device;

3 is a sectional view of a built-in motor type injection device according to a first embodiment of the present invention;

4 is a sectional view of a main part of a built-in motor type injection device according to a first embodiment of the present invention;

Figure 5 is a graph for comparing injection characteristics;

6 is a sectional view of a built-in motor type injection device according to a second embodiment of the present invention;

7 is a sectional view of a built-in motor type injection device according to a third embodiment of the present invention;

Fig. 8 is an explanatory view of a driving section housing in a built-in motor type injection device according to a fourth embodiment of the present invention;

9 is a sectional view of a driving section of a built-in motor type injection device according to a fourth embodiment of the present invention; and

Fig. 10 is a side view of the front frame in the fourth embodiment of the present invention.

Best Mode for Carrying Out the Invention

Embodiments of the present invention will be explained in detail below with reference to the accompanying drawings.

3 is a sectional view of a built-in motor type injection device according to a first embodiment of the present invention; FIG. 4 is a sectional view of a main part of a built-in motor type injection device according to a first embodiment of the present invention; 5 is a graph for comparing injection characteristics. In Fig. 5, the horizontal axis represents time and the vertical axis represents injection speed.

In FIGS. 3 and 4, reference numeral 12 denotes a heating cartridge, which serves as a cartridge member. The heating cartridge 12 has an injection nozzle 12a at its front end (left side in FIG. 3). A screw 22 serving as an injector is installed in the heating cylinder 12 such that the screw 22 can rotate and advance and retreat (moving left and right in FIG. 3 ).

The screw 22 has a screw head 22a at its front end, and extends backward (to the right in FIG. 3 ) in the heating cylinder 12 . The rear end (the right end in FIG. 3 ) of the screw rod 22 is fixed on a bearing housing 12 . Furthermore, a thread 23 is formed on the outer peripheral surface of the screw so as to form a groove 26 .

A resin supply port 29 is formed at a predetermined position in the heating cylinder 12, and a hopper 30 is fixed to the resin supply port 29. As shown in FIG. The resin supply port 29 is formed in such a position that when the screw 22 is at the frontmost position (leftward in FIG. 3 ) in the heating cylinder 12, the resin supply port 29 faces the rear end portion of the groove 26 (rightward in FIG. 3 ). end).

During a metering phase, the screw 22 retreats a predetermined distance (ie, moves to the right in FIG. 3 ) and keeps rotating so that powdery resin is supplied from the hopper 30 into the heating cylinder 12 . Resin 33 progresses along groove 26 (ie, moves to the left in FIG. 3 ).

In addition, an unillustrated heater serving as heating means is disposed around the heating cylinder 12 as shown in the figure. The heater heats the cartridge 12 to melt the resin in the tank 26 . Thus, as the screw 22 retreats by a predetermined distance and keeps rotating, the molten resin required for one shot is collected in front of the screw head 22a.

In a subsequent injection stage, as the screw 22 advances, the resin accumulated in front of the screw head 22a is injected from the injection nozzle 21a and filled into a cavity of an unillustrated mold device.

A driving section 15 is installed at the rear end of the heating cylinder 12, in order to drive the screw rod 22 to rotate, advance and retreat, the driving section 15 includes a base frame 17, a metering motor 81 used as the first driving device and a metering motor 81 used as the first driving device. The injection motor 82 of the second driving device. The metering motor 81 is mounted on the base frame 17 in a movable manner. The injection motor 82 is fixed on the base frame 17 . The injection motor 82 is mounted on the same axis as the screw 22 .

A guide rod 83 serving as a guide is mounted on the base frame 17 such that the guide rod 83 extends parallel to the screw rod 22 . The metering motor 81 moves along the guide rod 83 . For this purpose, a support plate 84 is slidably supported by guide rods 83 and the metering motor 81 is fixed on the support plate 84 .

Furthermore, a driving side pulley 86 is fixed to an output shaft 85 of the metering motor 81 , and a driven side pulley 88 is fixed to the outer periphery of a case 87 of the bearing case 13 . A timing belt 89 is stretched between and wound around the driving side pulley 86 and the driven side pulley 88 . The driving side pulley 86 , the driven side pulley 88 and the timing belt 89 constitute transmission means to connect the bearing housing 13 and the metering motor 81 .

The injection motor 82 includes a stator 91 fixed on the base frame 17 and a rotor 92 arranged inside the stator 91 . The rotor 92 is supported by the base frame 17 and is rotatable relative to the latter. Specifically, a hollow rotor shaft 93 is fixedly fitted in the rotor 92 , and the other end of the rotor shaft 93 is supported by the base frame 17 through bearings 94 and 95 .

Bearings 96 and 97 are housed in bearing housing 13 . The screw 22 is connected to a ball screw shaft/spline shaft unit 98 serving as a transmission shaft through bearings 96 and 96 so that the screw 22 and the ball screw shaft/spline shaft unit 98 can rotate relative to each other. A ball nut 99 is fixed to the base frame 17 through a load cell 105 serving as a load detecting device, and the ball nut 99 is connected to a ball screw shaft formed in the front half of the ball screw shaft/spline shaft unit 98 and used as a motion conversion part. Portion 98a is engaged. The bearing housing 13 constitutes a driving force transmission device, so that the screw 22 and the ball screw shaft/spline shaft unit 98 can rotate relative to each other, and at the same time restricts the axial movement between the screw rod 22 and the ball screw shaft/spline shaft unit 98 . In addition, the ball nut 99 and the ball screw shaft portion 98a constitute motion conversion means to convert rotational motion into linear motion.

In this way, in a metering stage, when the metering motor 81 starts, the rotation of the metering motor 81 will be sequentially transmitted to the drive side pulley 86, the timing belt 89, the casing 87 and the screw 22, so that the screw 22 rotates. In this case, the screw 22 and the ball screw shaft/spline shaft unit 98 are rotatably connected to each other through the bearing housing 13 . Therefore, the transmitted rotational motion of the case 87 is not transmitted to the ball screw shaft/spline shaft unit 98; however, the pressure of the resin in the heating cartridge 12 is transmitted to the ball screw shaft/spline shaft through the bearing housing 13 on unit 98. As a result, the ball screw shaft/spline shaft unit 98 can keep rotating while retracting, and the screw 22 can also keep rotating while moving backward. When the screw 22 is retracted, back pressure is exerted on the screw 22 to resist the pressure of the resin.

The screw 22 is advanced by applying an electric current having a predetermined frequency to the stator 91 of the injection motor 82 . For this purpose, an annular engaging member 101 is fixed on the inner periphery of the rotor shaft 93, and is located on the substantially central portion of the rotor shaft, so that a spline 102 formed on the inner peripheral surface of the engaging member 101 and a spline formed on the A spline shaft portion 98b on the rear half of the ball screw shaft/spline shaft unit 98 and serving as a rotation transmission portion engages. The spline 102 and the spline shaft portion 98b constitute a rotation transmission means to transmit the rotational motion of the injection motor 82 .

Thus, during an injection phase, when the injection motor 82 is activated, the rotational motion of the injection motor 82 will be sequentially transmitted to the rotor shaft 93, the snap piece 101 and the ball screw shaft/spline shaft unit 98. Since the ball nut 99 is fixed to the base frame 17, the ball screw shaft/spline shaft unit 98 advances as it rotates, and the screw 22 also advances. At this time, the injection force acting on the ball screw shaft/spline shaft unit 98 is transmitted to the dynamometer 105 through the ball nut 99 and detected by the dynamometer 105 .

The ball screw shaft/spline shaft unit 98 can be retracted by a stroke S in the axial direction.

As described above, since the rotational motion of the injection motor 82 is directly transmitted to the ball screw shaft/spline shaft unit 98, it is not necessary to add a reduction mechanism, a pulley, or the like. Thus, mechanical efficiency is increased while inertia is reduced. As a result, as shown in Fig. 5, during the injection phase, the time required to establish and change the injection speed can be shortened, and the torque required to establish and change the injection speed can be reduced. In addition, the time required to switch from the injection phase to the packing phase is reduced. In Fig. 5, line L1 represents the injection characteristics of the conventional injection device shown in Fig. 1; line L2 represents the injection characteristics of the conventional built-in motor type injection device shown in Fig. 2; line L3 represents the built-in motor type injection device shown in Fig. 3 injection properties.

Since the engaging member 101 is fixed at a substantially central portion on the rotor shaft 93, the spline shaft portion 98b can advance and retreat in the rotor 92. As shown in FIG. Furthermore, the drive side pulley 86 , the driven side pulley 88 and the timing belt 89 , all of which transmit the rotational movement of the metering motor 81 to the screw 22 , can be axially superimposed on the bearing housing 13 . Thus, the axial length of the injection molding machine can be reduced.

In this embodiment, the metering motor 81 and the ball screw shaft/spline shaft unit 98 are mounted on different axes. However, the injection motor, ball screw shaft/spline shaft unit and screw can also be mounted on different axes.

Next, a second embodiment of the present invention will be explained.

Fig. 6 is a sectional view of a built-in motor type injection device according to a second embodiment of the present invention.

In FIG. 6, reference numeral 111 denotes a drive section housing. A metering motor 144 serving as a first driving device is arranged at the front of the driving section housing 111 (the left part in FIG. 6 ), and an injection motor 145 serving as a second driving device is arranged at the rear of the driving section housing 111. part (the right part in FIG. 6 ), so that the metering motor 144 and the injection motor 145 share a central axis. The metering motor 144 includes a stator 146 and a rotor 147 , while the injection motor 145 includes a stator 148 and a rotor 149 .

The rotor 147 is supported by the drive section housing 111 and is rotatable relative to the latter. Specifically, a hollow first rotor shaft 156 is fixedly fitted in the rotor 147 , and the first rotor shaft 156 is supported by the driving section housing 111 through bearings 151 and 152 .

Likewise, the rotor 149 is supported by the drive section housing 111 and is rotatable relative to the latter. Specifically, a hollow second rotor shaft 157 is fixedly fitted in the rotor 149 , and the second rotor shaft 157 is supported by the drive section casing 111 through bearings 153 and 154 .

During a metering phase, the screw 22 ( FIG. 4 ) used as the injector will be driven back by the metering motor 144 and keep rotating. In order to realize this movement, a cylindrical spline sleeve 162 and a cylindrical guide rod 112 are mounted on the front end of the first rotor shaft 156; a bearing housing 113 is slidably installed in the guide rod 112; and The bearing housing 113 is connected to the screw rod 22 via a rod 114 . The spline sleeve 162 extends from the front end portion (the left end portion in FIG. 6 ) of the first rotor shaft 156 to a position close to the center. The spline sleeve 162 is spline-engaged with a spline shaft portion 163 formed at the rear end (the right end in FIG. 6 ) of the bearing housing 113 . In this way, when the rotor 147 is driven by the metering motor 144 to rotate, the rotational movement of the rotor 147 will be transmitted to the screw 22 , thereby driving the screw 22 to rotate. At this time, the spline shaft portion 163 retreats relative to the spline sleeve 162 (moves to the right in FIG. 6 ), so that the screw 22 also retreats. In this way, the metering operation can be completed. It should be noted that when the screw 22 retreats, there will be back pressure applied to the screw 22 to resist the pressure generated by the resin.

In addition, during an injection stage, the screw 22 is driven forward by the injection motor 145 without rotation. To achieve this movement, bearings 166 and 167 and a thrust bearing 168 are mounted in bearing housing 113 . The front end of a ball screw shaft/spline shaft unit 165 serving as a transmission shaft is rotatably supported by bearings 166 and 167 , and a thrust load is received by a thrust bearing 168 . At a position between the rear end of the first rotor shaft 156 and the front end of the second rotor shaft 157, a ball nut 169 is fixed on the driving section housing 111. The ball nut 169 is engaged with a ball screw shaft portion 123 formed in the front half of the ball screw shaft/spline shaft unit 165 and serving as a motion converting portion. In addition, a cylindrical engaging member 121 is mounted on the rear end of the second rotor shaft 157 . The snap piece 121 extends from the rear end portion (the right end portion in FIG. 6) of the second rotor shaft 157 to a position near the center, and a spline 122 is formed on the front inner periphery of the snap piece. Through the spline 122, the engaging member 121 engages with a spline shaft portion 124 formed on the rear half of the ball screw shaft/spline shaft unit 165 and serving as a rotation transmission portion. That is to say, the front end of the ball screw shaft/spline shaft unit 165 is supported by the bearing 151 on the drive section casing 111 through the bearing housing 113 and the first rotor shaft 156 and can rotate relative to the latter, while the ball screw shaft/spline shaft unit 165 The rear end of the key shaft unit 165 is supported by the bearing 154 on the driving section housing 111 via the snap piece 121 and the second rotor shaft 157 and is rotatable relative to the latter. The bearing housing 113 constitutes a driving force transmission device, so that the screw 22 and the ball screw shaft/spline shaft unit 165 can rotate relative to each other while restricting the axial movement between the screw rod 22 and the ball screw shaft/spline shaft unit 165 . In addition, the snap piece 121 and the spline shaft portion 124 constitute a rotation transmission means to transmit the rotational motion of the injection motor 145 . Whereas the ball nut 169 and the ball screw shaft portion 123 constitute motion conversion means to convert rotational motion into linear motion.

An end cover 131 is fixed on the rear end of the second rotor shaft 157 . The end cover 131 seals the inside of the second rotor shaft 157 to prevent foreign substances from entering. In addition, an encoder 132 is mounted on the end cover 131 to directly detect the number of rotations of the ball screw shaft/spline shaft unit 165 . Thus, in a control section not shown, the position of the ball screw shaft/spline shaft unit 165 can be calculated according to the number of revolutions of the ball screw shaft/spline shaft unit 165 .

In this embodiment, the rotation of the rotor 149 is transmitted to the ball screw shaft/spline shaft unit 165 through the second rotor shaft 157 and the snap piece 121, and this transmitted rotational motion is in turn transmitted by the ball nut 169 and the ball screw shaft part 123 is converted into linear motion, thereby advancing and retreating the ball screw shaft/spline shaft unit 165 (moving left and right, respectively, in FIG. 6 ). Therefore, when the rotor 149 is rotated by the injection motor 145 to advance the ball screw shaft/spline shaft unit 165, the screw 22 advances without rotating. In this way, the injection operation can be completed.

In the structure described above, the rotation of the metering motor 144 and the rotation of the injection motor 145 are transmitted to the screw 22 without adding a reduction mechanism, a pulley, or the like. Thus, mechanical efficiency is increased while inertia is reduced.

Since the spline 122 is disposed on a substantially central portion of the rotor 149 , the spline shaft portion 124 can advance and retreat in the rotor 149 . Furthermore, a splined sleeve 162 and a splined shaft portion 163 for transmitting the rotational movement of the metering motor 144 to the screw 22 may be axially superimposed on the ball screw shaft portion 123 . Therefore, the axial length of the injection molding machine can be reduced.

Next, a third embodiment of the present invention will be explained. The same structures as those in the second embodiment are denoted by the same reference numerals, and their explanations are omitted.

Fig. 7 is a sectional view of a built-in motor type injection device according to a third embodiment of the present invention.

In FIG. 7 , reference numeral 210 denotes a driving section casing, which is composed of a front casing 221 , a center casing 222 and a rear casing 223 . The rear case 223 is composed of a cylindrical portion 226 and end plates 224 and 225 covering opposite ends of the cylindrical portion 226 . A metering motor 201 serving as a first driving means is housed in the front end (left end in FIG. 7 ) of the center case 222 , and an injection motor 145 serving as a second driving means is housed in the rear case 223 . The metering motor 201 and the screw 22 ( FIG. 4 ) serving as the injection part are mounted on different parallel axes. The injection motor 145 and the screw rod 22 are installed on the same axis. At the front end of the center case 222, a spline nut 211 is rotatably supported by bearings 213 and 214, and a spline 212 is formed on the inner periphery of the rear end (the right end in FIG. 7 ) of the spline nut 211. superior. A drive side gear 203 is mounted on an output shaft 202 of the metering motor 201 and meshes with an idler gear rotatably supported on the front end 221 . A driven side gear 205 is mounted on the front end of the spline nut 211 and meshes with the idler gear 204 . In this way, the rotational motion generated after starting the metering motor 201 will be transmitted to the spline nut 211 through the driving side gear 203 , the idler gear 204 and the driven side gear 205 .

A bearing housing 231 is disposed radially inside the driven side gear 205 and the spline nut 211 . A spline 232 is formed on the outer peripheral surface of the bearing housing 231, and the bearing housing 231 engages the spline nut 211 through the spline.

The driving side gear 203 , the idler gear 204 and the driven side gear 205 constitute a transmission to connect the bearing housing 231 and the metering motor 201 .

The screw 22 can be driven forward (to the left in FIG. 7 ) by the injection motor 145 without rotation. Bearings 166 and 167 and thrust bearing 168 are mounted in bearing housing 231 for this purpose. The front end of a ball screw shaft/spline shaft unit 165 serving as a transmission shaft is rotatably supported by bearings 166 and 167 , and a thrust load is received by a thrust bearing 168 . In addition, at a position between the rear end of the central housing 222 and the front end of the second rotor shaft 157, a ball nut 169 is fixed on the central housing 222, and is formed in the front half of the ball screw shaft/spline shaft unit 165. And the ball screw shaft portion 123 serving as a motion converting portion is engaged. The ball nut 169 and the ball screw shaft/spline shaft unit 165 constitute motion conversion means to convert rotational motion into linear motion.

Like this, in a metering stage, after metering motor 201 is started, the rotary motion of metering motor 201 is transmitted to driving side gear 203, idler 204, spline nut 211, bearing housing 231, rod 114 and screw rod 22 in sequence, in this In this case, since the screw rod 22 is connected to the ball screw shaft/spline shaft unit 165 through the bearing housing 231, there can be relative rotation between them. Thus, although the rotational motion transmitted to the bearing housing 231 is not transmitted to the ball screw shaft/spline shaft unit 165, the resin pressure in the heating cylinder 12 is transmitted to the ball screw shaft/spline shaft through the bearing housing 231 Unit 165 on. In this way, the ball screw shaft/spline shaft unit 165 backs up (moves to the right in FIG. 7 ) and keeps rotating, causing the screw 22 to also back up. When the screw 22 retreats, back pressure is applied to the screw 22 against the pressure generated by the resin.

In addition, in an injection stage, when the injection motor 145 is activated, the rotational motion of the injection motor 145 is sequentially transmitted to the second rotor shaft 157 , the snap-fitting member 121 and the ball screw shaft/spline shaft unit 165 . Since the ball nut 169 is secured to the center housing 222, the ball screw shaft/spline shaft unit 165 advances and keeps rotating, thereby advancing the screw 22 without rotating.

In this embodiment, since the spline 122 is mounted substantially at the center of the second rotor shaft 157, the spline shaft portion 124 serving as a rotation transmission means can advance and retreat in the rotor 149 (leftward and rightward in FIG. 7 ). move). Furthermore, the driving side gear 203 , the idler gear 204 and the driven side gear 205 all for transmitting the rotational movement of the metering motor 201 to the screw 22 may be axially superimposed on the bearing housing 231 . Thus, the axial length of the injection molding machine can be reduced. The snap piece 121 and the ball screw shaft/spline shaft unit 165 constitute rotation transmission means.

Although the screw 22 is used as the injection member in the above embodiments, a plunger may be used instead of the screw 22 .

A fourth embodiment of the present invention is explained below.

Fig. 8 is an explanatory view of a drive section housing in a built-in motor type injection device according to a fourth embodiment of the present invention; Fig. 9 is a drive section of a built-in motor type injection device according to a fourth embodiment of the present invention and Figure 10 is a side view of the front frame in the fourth embodiment of the present invention. Fig. 8 is a sectional view along line X-X in Fig. 10 .

In FIGS. 8-11, reference numeral 311 denotes a driving section housing which surrounds the heating cylinder 12 (FIG. 4) serving as a cartridge member and is fixed to the rear end of the heating cylinder. The driving section housing 311 includes a front cover 313 ; a center frame 315 ; a rear cover 317 ; a front frame 341 connecting the front cover 313 ; and a rear frame 342 connecting the center frame 315 and the rear cover 317 . In this case, the front frame 341 and the rear frame 342 constitute a stator frame; the front cover 313, the center frame 315 and the rear cover 317 constitute an equipment rack; and the front frame 341 and the rear frame 342 also serve as an equipment rack. The front cover 313 and the front frame 341 are connected to each other in a detachable manner by the bolt b1; the front frame 341 and the central frame 315 are connected to each other in a detachable manner by the bolt b2; The mode of detachment is connected to each other; and the rear frame 342 and the rear cover 317 are connected to each other in a detachable mode through the bolt b4. For the front frame 341, the front cover 313 serves as a first plate, and the center frame 315 serves as a second plate. For the rear frame 342, the center frame 315 serves as a first plate, and the rear cover 317 serves as a second plate.

In this way, the front cover 313 can be separated from the front frame 341 by removing the bolt b1; the front frame 341 can be separated from the center frame 315 by removing the bolt b2; the rear frame 342 can be separated from the center frame 315 by removing the bolt b3; The rear cover 317 can be separated from the rear frame 342 by removing the bolt b4. Therefore, the metering motor 344 serving as the first driving means and the injection motor 345 serving as the second driving means can be replaced. As a result, assembly and maintenance of the injection molding machine is facilitated. Each metering motor 344 and injection motor 345 is a hollow type motor.

The metering motor 344 is arranged at the front portion (the left part in FIG. 9 ) of the driving section housing 311, and the injection motor 345 is arranged at the rear part (the right part among Fig. 9 ) of the driving section housing 111, so that the metering motor 344 It shares a central axis with the injection motor 345. The metering motor 344 includes a stator 346 supported on the front frame 341 and an annular rotor 347 disposed inside the stator 346 . The injection motor 345 includes a stator 348 supported on the rear frame 342 and an annular rotor 349 disposed inside the stator 348 .

The rotor 347 is supported by the drive section housing 311 and is rotatable relative to the latter. Specifically, a hollow first rotor shaft 356 is fixedly assembled in the rotor 347; the front end (the left end in Fig. 9) of the first rotor shaft 356 is supported on the front frame 341 by a bearing 351; and the first rotor The rear end (the right end in FIG. 9 ) of the shaft 356 is supported on the central frame 315 through a bearing 352 .

Likewise, the rotor 349 is supported by the drive section housing 311 and is rotatable relative to the latter. Specifically, a hollow second rotor shaft 357 is fixedly assembled in the rotor 349; the front end of the second rotor shaft 357 is supported on the central frame 315 by a bearing 353; and the rear end of the second rotor shaft 357 is supported by a bearing 354 Supported on the rear frame 342 .

When a current having a predetermined frequency is applied to the stator 346 of the metering motor 344, the screw 22 serving as the injector will retreat (move to the right in FIG. 9) and keep rotating. In order to realize this movement, a sleeve 318 is installed on the front of the first rotor shaft 356 and is located at the radial inner side of the first rotor shaft 356; In addition, at a predetermined position on the front rear side (the right side in FIG. 9 ) of the first rotor shaft 356, that is, on the rear end of the sleeve 318, there is arranged a first spline nut 362, which is fixed to the shaft by a bolt b12. The rear end of the sleeve 318. The first spline nut 362 is engaged with a first spline shaft 363 through splines. The screw rod 22 is fixed on the front end of the first spline shaft 363 . In this case, the first spline nut 362 and the first spline shaft 363 constitute the first driving force transmission means, so that relative axial movement can be carried out between the sleeve 318 and a first coupling 381, and at the same time In turn, the relative rotation between the sleeve 318 and the first coupling 381 is limited. The length of the first spline shaft 363 is equal to the stroke of the screw rod 22 .

In this way, when the rotor 347 rotates under the drive of the metering motor 344, the rotational motion of the rotor 347 will be transmitted to the screw through the first rotor shaft 356, the sleeve 318, the first spline nut 362 and the first spline shaft 363 in sequence. 22, so that the screw 22 rotates. As a result, the resin advances in the groove 26 (moves to the left in FIG. 9 ) and is melted, and the screw 22 retreats under the back pressure generated by the advance of the resin.

At this time, since the first spline nut 362 is engaged with the first spline shaft 363 through the spline, the first spline shaft 363 will retreat relative to the first spline nut 362.

In addition, when a current having a predetermined frequency is applied to the stator 348 of the injection motor 345, the screw 22 will advance without rotation. To achieve this movement, an annular bearing retainer 364 is fixed on the rear end of the second rotor shaft 357; a first shaft portion 365a of a ball screw shaft 365 is fixedly fitted in the bearing retainer 364. The ball screw shaft 365 is supported by the drive section housing 311 and is rotatable relative to the latter. Specifically, the ball screw shaft 365 is supported on the rear housing 317 by a bearing retainer 364 , a bearing 366 and a thrust bearing 368 . A rear cover 377 is fixed to the rear cover 317 by means of bolts b6 through a load cell 375 serving as a load detecting device. The second shaft portion 365b of the ball screw shaft 365 is supported on the rear cover 377 via a bearing 367 . An absolute pulse encoder 385 is mounted on the rear cover 377 via a bracket 386 . The absolute pulse encoder 385 is connected to the second shaft portion 365b and is used as a first rotation amount detecting means to detect the number of rotations of the ball screw shaft 365 or the number of rotations of the injection motor, and is also used as a screw position detecting means to detect the number of rotations of the injection motor according to the injection motor. The number of rotations and the position of the screw rod 22.

In addition, a ball nut 369 is installed in the second rotor shaft 357 so that the ball nut 369 can advance and retreat (move left and right in FIG. 9 ). The ball nut 369 comes into engagement with the ball screw shaft 365 to constitute a motion converting portion. Thus, when the injection motor 345 is activated to rotate the rotor 349, the rotational motion of the rotor 349 will be transmitted to the ball screw shaft 365 through the second rotor shaft 357 and the bearing retainer 364, thereby converting the rotational motion into a linear motion to move the balls. The nut 369 advances and retreats. In order to prevent the ball screw shaft 365 from coming out of the ball nut 369, a stopper 319 is fixed on the front end of the ball screw shaft 365 by a bolt b13.

In addition, in order to prevent the ball nut 369 from rotating together with the ball screw shaft 365, a sleeve-shaped second spline shaft 371 is fixed on the front end of the ball nut 369 through the bolt b11, and the second spline shaft 371 is engaged with a spline and fixed on the Second spline nut 376 on center frame 315 . In this case, the second spline nut 376 and the second spline shaft 371 constitute second driving force transmission means, so that the center frame 315 and a bearing serving as a third driving force transmission means will be explained later. The boxes 372 can move relative to each other in the axial direction, and at the same time, the relative rotational movement between the central frame 315 and the bearing box 372 is restricted. The length of the second spline shaft 371 is equal to the stroke of the screw rod 22 .

The bearing housing 372 is fixed on the front end of the second spline shaft 371 by the bolt b7. A thrust bearing 373 is accommodated in the bearing housing 372 at the front side of the bearing housing (left side in FIG. 9 ), and a bearing 374 is accommodated in the bearing housing 372 at the rear side of the bearing housing. In this case, the bearing housing 372 enables relative rotation between the first spline shaft 363 and the second spline shaft 371 while limiting the relative rotation between the first spline shaft 363 and the second spline shaft 371 . axial movement. Thus, the first spline shaft 363 is supported by the thrust bearing 373 and the bearing 374 and can rotate relative to the second spline shaft 371 and the ball nut 369 .

In addition, a rear end shaft 22b of the screw rod 22 is fixed to the front end of the first spline shaft 363 by means of bolts b8 and b9 through a first coupling 381 and a second coupling 382 . The first coupling 381 slides in the sleeve 318 as the screw 22 advances and retreats. In addition, a groove 363a is formed at the rear end of the first spline shaft 363 to prevent the first spline shaft 363 from colliding with the head of the bolt b13, otherwise, when the first spline shaft 363 is located at the retracted position, The above conflicts may arise. Thus, the axial length of the injection molding machine can be reduced.

Reference numeral 384 denotes an encoder, which is connected to the sleeve 318 through a gear train 387 . The encoder 384 is used as a second rotation amount detecting device to detect the number of rotations of the sleeve 318 or the number of rotations of the metering motor. Reference numeral 389 denotes a water cooling jacket, which is fixed on the front cover 313 by bolts b10. The water cooling jacket 389 is used to prevent heat from being transmitted from the rear end of the heating cylinder 12 to the front cover 313 .

Next, the operation of the driving section having the above structure will be explained.

During an injection phase, when a current is applied to the stator 348 of the injection motor 345, the rotor 349 will rotate, and the rotational motion of the rotor 349 will be transmitted to the ball screw shaft 365 through the second rotor shaft 357 and the bearing retainer 364, thereby The ball screw shaft 365 is rotated. At this time, the ball nut 369 does not rotate because the second spline shaft 371 engages with the second spline nut 376 fixed to the center frame 315 through splines. Thus, a thrust acts on the ball nut 369, thereby advancing the ball nut 369.

During the above-mentioned injection stage, the metering motor 344 is not activated, and the rotor 347 is in a stopped state. Therefore, the first spline shaft 363 disposed on the front side of the ball nut 369 will advance to drive the screw 22 to advance.

In the manner described above, the rotational motion of the injection motor 345 is converted into linear motion by the ball screw shaft 365 and the ball nut 369 . As a result, the resin collected in front of the screw 22 is injected from the injection nozzle 12a.

During a metering phase, when a current is applied to the stator 346 of the metering motor 344, the rotor 347 will rotate, and the rotational motion of the rotor 347 will be transmitted to the first rotor shaft 356, the sleeve 318 and the first spline nut 362 A spline shaft 363, so that the first spline shaft 363 rotates. The rotational motion of the first spline shaft 363 is transmitted to the screw 22 to rotate the screw 22 . As a result, the resin advances in the groove 26 and is melted, and the screw 22 retreats under the back pressure generated by the advance of the resin.

At this time, since the first spline nut 362 engages with the first spline shaft 363 through splines, the first spline shaft 363 moves backward relative to the first spline nut 362 .

In a state where the back pressure of the metered resin is controlled, the injection motor 345 is activated to rotate the rotor 349 in a direction to make the screw 22 retreat. At this time, the axial load acting on the screw 22 and other components is detected by the load cell 375, and the back pressure is calculated based on the load detection value. Alternatively, an unillustrated pressure sensor may be installed in the heating cylinder 12 to detect the pressure of the resin in the heating cylinder 12, thereby calculating the back pressure from the pressure detection value.

The front frame 341 is formed by a cylindrical portion 408 supported on the stator 346, and each end of the cylindrical portion 408 is integrally formed with a rectangular flange portion 421, respectively. The flange portion 421 has four corners 410, and each corner has a hole 409 for passing the bolt b1 or b2.

In order to enable the positioning of the front frame 341 relative to the front cover 313 , an annular stepped portion f1 is formed on the front cover 313 . Also, in order to enable the positioning of the front frame 341 relative to the center frame 315, an annular stepped portion f2 is formed on the center frame 315.

The rear frame 342 is formed by a cylindrical portion 418 supported on the stator 348, each end of the cylindrical portion 418 is integrally formed with a rectangular flange portion 422, respectively. The flange portion 422 has four corners 420 each having a hole 419 for passing the bolt b3 or b4.

In order to enable the positioning of the rear frame 342 relative to the center frame 315 , an annular stepped portion f3 is formed on the center frame 315 . Also, in order to enable the positioning of the rear frame 342 relative to the rear cover 317, an annular stepped portion f4 is formed on the rear cover 317.

As described above, the front cover 313 and the center frame 315 are connected by the front frame 341 , and the center frame 315 and the rear cover 317 are connected by the rear frame 342 . Furthermore, the front frame 341 is constituted by the cylindrical portion 408 and the flange portion 421 , while the rear frame 342 is constituted by the cylindrical portion 418 and the flange portion 422 . In this way, in the injection phase, when the injection motor 345 is activated to drive the ball screw shaft 365 to rotate so that the screw 22 advances to inject the resin from the heating cylinder 12, even if the reaction force of the injection force passes through the front cover from the heating cylinder 12 313 is transmitted to the front frame 341, and is transmitted to the rear frame 342 by the rear cover 317 as a pulling force, and the front frame 341 and the rear frame 342 will not be elongated. Therefore, the locking force of the bolts b1-b4 will not be weakened.

In addition, even if the locking force of the bolts b1-b4 is weakened, the front frame 341 and the rear frame 342 will not rotate after starting the metering motor 344 or the injection motor 345, because the front cover 313 and the front frame 341 are fixed by the bolt b1 Together, the front frame 341 and the center frame 315 are fixed together by the bolt b2, the center frame 315 and the rear frame 342 are fixed together by the bolt b3, and the rear frame 342 and the rear cover 317 are fixed together by the bolt b4.

In this way, the locking force of the bolts b1-b4 does not need to be strictly controlled, so the assembly and maintenance of the injection molding machine are very convenient.

In this embodiment, the sleeve 318 is mounted on the front of the first rotor shaft 356 and located radially inside the first rotor shaft 356 ; and the front end of the sleeve 318 is fixed on the front end of the first rotor shaft 356 . In addition, the first spline nut 362 is fixed on the rear end of the sleeve 318; the first spline nut 362 engages the first spline shaft 363 by splines at almost the center of the first rotor shaft 356; and the screw rod 22 is fixed at the front end of the first spline shaft 363 .

Therefore, when the screw rod 22 is located at the backward end of the stroke, the rear end of the screw rod 22 can be located at a position slightly shifted forward from the center of the first rotor shaft 356, that is, a certain distance is spaced backward from the front end of the first rotor shaft 356 position, the distance is equal to the length of the sleeve 318 .

In this case, the screw 22 may overlap with the metering motor 344 when the screw 22 advances or retreats. Therefore, the axial length of the injection molding machine can be reduced.

The invention is not limited to the embodiments described above. Various modifications and alterations can be made to the present invention according to the spirit of the present invention, and they are included in the scope of the present invention.

Industrial Applicability

The present invention can be used in motor-driven injection molding machines.

Claims (5)

1. An injection molding machine comprising: a cylindrical piece; an injection member disposed in said cylindrical member so that said injection member can be advanced and retracted; an injection motor; a drive shaft arranged on the same axis as the injection motor and driven to rotate by the injection motor; a dynamometer arranged on the same axis as said drive shaft to allow axial movement between the drive shaft and the dynamometer; and a thrust bearing arranged on the same axis as the shaft of the dynamometer so that the thrust bearing can advance and retreat. 2. Injection molding machine according to claim 1, characterized in that the transmission shaft is used as a ball screw shaft. 3. The injection molding machine of claim 1, wherein the drive shaft rotates relative to the dynamometer. 4. The injection molding machine of claim 1, wherein the bearing retainer is disposed between the drive shaft and the thrust bearing. 5. The injection molding machine of claim 1, wherein the thrust bearing is arranged at a distal portion of the transmission shaft.

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