JPH02160477A - Screw tightening device - Google Patents

Abstract

PURPOSE:To correctly perform in a short time the fastening work of a screw class at specified torque by providing a clutch for transmitting a specific torque to an output shaft from an input shaft and providing an impact bestowing mechanism giving impact force over the rotating direction to this output shaft according to the relative rotation of this input shaft and output shaft. CONSTITUTION:In case of a screw class being fastened to some extent an input shaft and output shaft 6 are relatively rotated according to a clutch 15 being slided and an impact giving mechanism (the steel ball 30 escaped from a recess- part 27) gives an impact force over the rotating direction to the output shaft 6 in the state of holding the fastening torque. Then, while this impact force being applied, the fastening torque by the creep, etc., of the soft material, etc., contained in the body to be fastened or the torque equivalent to the reduction of the axial force of the screw class is supplemented and the fastening of the screw class by the engaging part 4 provided at the tip of the output shaft 5 is surely performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application in Business A) The screw tightening device according to the present invention is used to tighten screws such as screws, bolts, nuts, etc. to a predetermined tightening torque.

(Prior Art) Screws such as screws, bolts, and nuts are widely used in various mechanical devices to connect component parts to each other or to apply a predetermined force such as preload to a predetermined part. There is.

When tightening these screws, maintaining the tightening torque at a specified value maintains the joint strength between the parts connected by the screws as designed, or applies a specified preload, etc. It is necessary for this purpose.

In order to automatically tighten screws to a predetermined torque, it has traditionally been possible to use an electric motor, compressed air, or hydraulic pressure to tighten the screws to a predetermined tightening force. A tightening device has been used in which a predetermined tightening torque is obtained by applying an impact force using a hammer mechanism or the like.

(Problem to be Solved by the Invention) However, when tightening screws such as bolts and nuts, objects to be tightened that are connected or fixed to relative members include relatively soft materials such as gaskets and non-metallic materials. materials,
Contains materials with elasticity and plasticity.

When these items are tightened using conventional methods, they are tightened using a mechanical torque limiter or the stall torque of the motor (t). It is known that the amount decreases within a short period of time (several seconds), resulting in instability of the tightening torque.

In addition, with the impact force method using a hammer mechanism, etc., the impact force required for tightening fluctuates greatly, the torque is unstable, and furthermore, fluctuations in the tightening time have a large effect on the tightening torque. There were problems such as

In order to deal with the above-mentioned problems, the present invention has been developed to control tightening by adjusting the setting value of the tightening device according to the object to be tightened, including soft materials, elastic materials, plastic materials, etc. This was done for the purpose of minimizing the decrease in the axial force of the screws and stabilizing the tightening torque or the axial force of the screws.

(Mechanism for Solving the Problems) The screw tightening device of the present invention has an output that has an engaging portion at its tip that can be freely engaged with and detached from the end of the screw to be tightened! i+b
, an input shaft rotationally driven by a motor, a clutch provided between the input shaft and the output shaft to transmit a predetermined torque from the input shaft to the output shaft, and a relative relationship between the input shaft and the output shaft. The output shaft is configured with an ffi'l applying mechanism that applies an impact force in the rotational direction to the output shaft as it rotates.

(Function) When tightening screws such as screws, bolts, nuts, etc. with a predetermined torque using the screw tightening device of the present invention configured as described above, the engaging portion and the end of the screw are tightened. The input shaft is rotated by the motor with the clutch engaged and transmitting a predetermined torque.

As a result, the output shaft tightens the screws with a predetermined torque transmitted by the clutch.

When the screws are tightened, the input shaft and output shaft rotate relative to each other as the clutch slips, and while the tightening torque is maintained, the impact applying mechanism rotates to the output shaft. Apply impact force in different directions. While this impact force is being applied, the tightening torque due to the creep of the soft material included in the tightened object or the torque corresponding to the decrease in the axial force of the screws is added, and the output shaft is To ensure that screws are tightened by an engaging part provided at a tip.

(Example) Next, the present invention will be explained in more detail while explaining the illustrated embodiment.

1 to 4 show an embodiment of the present invention, FIG. 1 is a vertical cross-sectional side view of the upper half showing the overall configuration, and FIG. Figure 3 is a sectional view taken along the line A-A in Figure 2, and Figure 4 shows the tightening torque applied to the screws through the locking part during tightening work and the direction in which the screws are pulled. FIG. 3 is a diagram showing the relationship with axial force.

In FIG. 1, reference numeral 1 denotes an engaging part that can be freely engaged and detached from the head of a bolt, which is a type of screw to be tightened, and a socket 2,
It is composed of a support piece 3 that locks this socket 2. Engagement cylinder part 4 that allows the head of the bolt to fit inside without rattling
The base end of the socket 2, which has a tip formed at its tip, is inserted non-rotatably into a square hole 5 formed in the support piece 3, and the socket 2 is fixed by a set screw 43 screwed into the side surface of the support piece 3
The puller is prevented from falling from the support piece 3.

Further, the base end portion of the support piece 3 is fitted into the cylindrical holding cylinder portion 7 formed at the distal end portion of the output @6 without wobbling. The output shaft 6 is rotatably supported by a rolling bearing 13 on the upper end of a first support leg 12 fixed to the upper surface of the tip of the base 11, and the output shaft 6 is rotated in the twisting direction. By rotating it, the bolt can be tightened via the support piece 3 and the socket 2.

On the other hand, both ends of the bottle 8 passing through the base end of the support piece 3 in the diametrical direction are attached to the holding cylinder part 7 in the axial direction (the first
in the left and right direction in the figure), and
The support piece 3 is coupled to the output shaft 6 so that it can be freely displaced only in the axial direction. A compression spring 10 is provided between the inner back surface of the holding cylinder portion 7 and the base end surface of the support piece 3.
is provided on the support piece 3 and the socket 2 supported by this support piece 3 in the direction away from the output shaft 6 (left direction in FIG. 1).
gives it elasticity.

The first support leg 14 provided on the upper surface of the intermediate portion near the tip of the base 11 has a built-in solenoid and magnetic powder (not shown for brevity), and the transmission torque can be adjusted by changing the amount of current applied to the solenoid. A flexible electromagnetic clutch 15 is supported.

This electromagnetic clutch 15 is constructed by arranging a clutch output shaft 16 and a clutch input shaft 17, each of which is formed in a cylindrical shape, concentrically with each other. It is fitted inside the clutch output ll1II116 and is further fixed to the clutch output shaft 16 by a set screw 18.18.

Further, a motor 20 for rotationally driving the output shaft 6 via the electromagnetic clutch 15 is supported on a third support leg 19 provided on the upper surface of the intermediate portion of the base 11 . The driving force of an annular motor 20 having a through hole 21 in the center is taken out by a rotating tid 22 also formed in an annular shape, and a ring body 24 which is connected and fixed to this rotating shaft 22 by a screw 23.
is transmitted to the clutch input shaft 17 via. A rolling bearing 25 is provided between the inner circumferential surface of the ring body 24 and the outer circumferential surface of the clutch output shaft 16, so that the two members 24, 16 can freely rotate relative to each other.

A plurality of concave portions 27 and 27 in the shape of a mortar as shown in FIGS. They are formed on a single circular arc centered on the axis 6 at equal intervals.

On the other hand, a ring-shaped holder 28 is screwed and fixed to a portion of the base end of the output shaft 6 that is located inside the ring body 24 . The outer peripheral edge of this holder 28 has the above-mentioned recess 27.27.
The same number of notches 29 are formed at the same pitch as the recesses 27, 27, and a steel ball 30 is loosely fitted into each notch 29.

31 is a pressing ring that elastically presses each steel ball 30 toward the stepped portion 26 in which the recessed portion 27.27 is formed;
A31 is a rolling bearing 32, such as a deep groove type or an angular type, that can support force in the thrust direction (left and right direction in Fig. 1).
It is rotatably supported at the tip of the pressing rod 33 via.

This pressing rod 33 is connected to a lateral slide bearing 34.
．． 34, it is supported inside the through hole 21 provided at the center of the motor 20 so as to be freely displaceable in the axial direction (left-right direction in FIG. 1). A receiving plate 35 is fixed to a portion of the base end of the pressing rod 33 that protrudes from the through hole 21 .

On the other hand, a fourth support leg 36 is provided on the upper surface of the base end of the base 11, and a screw hole 3 formed at the upper end of this support leg 36 is provided.
A hollow adjustment screw 38 is screwed into 7. and,
A compression spring 40 is provided between the inner surface of the hole 39 formed inside the adjustment screw 38 and the receiving plate 35. Therefore, due to the elasticity of the compression spring 40, the pressing ring 31 is moved to the first
It is provided with elasticity directed to the left in the figure, and the magnitude of this elasticity can be adjusted freely by rotating an adjustment screw 38.

Further, the support arm 41 of the fourth support leg 36 supports a sensor 42 for detecting movement of the receiving plate 35. As this sensor 42, a proximity switch or a microswitch can be used, and by detecting the number of times the receiving plate 35 moves in the left and right direction in FIG.
The number of impacts applied to the output shaft 6 by the impact applying mechanism consisting of 7 can be counted.

When tightening screws such as bolts to a predetermined torque using the screw tightening device of the present invention configured as described above,
An engaging cylinder portion 4 provided at the tip of a socket 2 constituting the engaging portion 1 is externally fitted onto the head of the bolt. In this way, the engaging cylinder portion 4
When the two members are brought close to each other in order to externally fit the bolt onto the head of the bolt, the pin 8 fixed to the support piece 3 is displaced within the elongated hole 9 formed in the holding cylinder portion 7 of the output shaft 6, and the compression spring 1
0, the socket 2 is pushed into the holding cylinder part 7. For this reason, the engagement cylinder part 4 is elastically pressed toward the head of the bolt, and as the tightening work is performed subsequently, the engagement cylinder part 4 and the head of the bolt become engaged. will not come off carelessly.

In this way, once the engagement tube 4 and the head of the bolt are engaged with each other, a predetermined current is applied to the solenoid constituting the electromagnetic clutch 15, and the electromagnetic clutch 15 transmits a predetermined torque. By energizing the motor 20, the rotating shaft 22 of the motor 20 is rotated, and the clutch input shaft 17 is rotated via the annular body 24.

The rotational driving force transmitted to the clutch input shaft 17 in this way is all clutch output! l! The predetermined torque T set to the electromagnetic clutch 15 is not transmitted to the ll116.
(Fig. 4) is transmitted to the clutch output shaft 16,
A bolt is rotated with a predetermined torque T via the output shaft 6, the support piece 3, and the socket 2, and the bolt is tightened. At this time, the tightening torque applied to the bolt changes as shown by the solid line in FIG. 4, and accordingly, the axial force acting in the direction of pulling the bolt changes as shown by the chain line in the same figure.

After a minute time t has passed after the start of the tightening work, when the bolt is tightened to a certain extent, the torque required to rotate the bolt exceeds the driving torque T transmitted to the socket 2, and the electromagnetic clutch 15 slips. , the socket 2, the support piece 3, and the output @6, the holder 28, which is non-rotatably coupled to the socket 2, stops rotating.

At this point, the motor 20 is still rotating, and the ring body 24 on which the steel ball 30 loosely fitted into the notch 29 of the holder 28 is in contact is also continuing to rotate. The operation of escaping from the mortar-shaped recess 27.27 formed in the stepped portion 26 of the ring body 24 or fitting into this recess 27.27 is repeatedly performed.

Each steel ball 30 is moved to the recess 27 by a compression spring 40 via a receiving plate 35, a pressing rod 33, a rolling bearing 32, and a pressing ring 31.
．． 27 is elastically pressed, and each steel ball 30
A mortar-shaped recess 27.2 formed in the step 26 of the ring body 24
At the moment of escape from the retainer 28, an instantaneous impact torque having a magnitude as shown in FIG.
to output @6 via.

This impact torque causes the bolt to be retightened, and the axial force applied to the bolt increases momentarily.
This axial force rapidly decreases after the impact torque disappears due to the above-mentioned creep of the tightened body, or due to the fit of the washer or the fit between the bolt and nut.

However, the engagement and disengagement between the steel ball 30 and the recesses 27 and 27 is repeated within a short period of time, and each time an impact torque is applied in the direction of tightening the bolt, so that the bolt is repeatedly tightened.

When the bolt is repeatedly tightened in this way, as shown by the broken line in Figure 4, the decrease in the bolt's axial force after the impact torque disappears gradually becomes gradual, and the bolt's axial force (tightening force) gradually approaches the desired value.

The number of times impact torque is applied to the bolt matches the number of reciprocations of the receiving plate 35 detected by the sensor 42, so if the sensor 42 counts the predetermined number of impact torques, the bolt has been sufficiently tightened. Assuming that the tightening work has been completed, the tightening work is completed. Note that this tightening work is actually performed within a short period of time.

In addition, in the illustrated embodiment, the socket 2 is shown to fit into the head of the bolt, but when tightening a screw or nut, it can be attached to a socket with a corresponding shape. exchange.

Further, contrary to the illustrated embodiment, a plurality of recesses 27.27 are formed in the output side member, and a plurality of steel balls 30 entering and leaving the recesses 27.27 are locked to a part of the input side member. I can do things. In this case, for example, the press ring 31 is fitted onto the output side member so as to be movable in the axial direction, and this press T! The pressing ring 31 is pressed against the steel ball 30 by the elasticity of the spring provided in the j131 and the portion fixed to the output side portion.

(Effects of the Invention) The screw tightening device of the present invention is configured and operates as described above, so that it can tighten screws such as screws, bolts, nuts, etc. to a predetermined torque in a short period of time. It can be done accurately.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, FIG. 1 is a vertical cross-sectional side view of the upper half showing the overall configuration, and FIG. Figure 3 is a sectional view taken along the line A-A in Figure 2, and Figure 4 shows the tightening torque applied to the screws through the locking part during tightening work and the direction in which the screws are pulled. FIG. 3 is a diagram showing the relationship with axial force. 1. Engagement part, 2: Socket, 3: Support piece, 4: Engagement cylinder part, 5: Square hole, 6: Output shaft, 7: Holding cylinder part, 8: Bottle, 9: Long hole, 10: Compression Spring, 11, base, 12: first support leg, 13: rolling bearing, 14: second support leg,
15: Electromagnetic clutch, 16: Clutch output shaft, 17: Clutch input shaft, 18: Set screw, 19: Third support leg,
20: Motor, 21; Through hole, 22: Rotating shaft, 23: Screw, 24: Annular body, 25: Rolling bearing, 26: Step, 27
: recess, 28: holder, 29; notch, 30: steel ball,
31: Pressing ring, 32: Rolling bearing, 33: Pressing rod,
34: Lateral slide bearing, 35: Support plate, 36: Fourth support leg, 37: Screw hole, 38: Adjustment screw, 39: Hole, 4
0: compression spring, 41: support arm, 42: sensor, 43: locking screw. Chiku 2g 3rd Ward Circle B Kima

Claims (3)

[Claims] (1) An output shaft with an engaging part at its tip that can be freely engaged and detached from the end of the screw to be tightened, an input shaft that is rotationally driven by a motor, and an engaging part that is provided between this input shaft and the output shaft. a clutch that transmits a predetermined torque from the input shaft to the output shaft; and an impact applying mechanism that applies an impact force in the rotational direction to the output shaft as the input shaft and the output shaft rotate relative to each other. A screw tightening device consisting of. (2) The impact applying mechanism consists of a plurality of mortar-shaped recesses formed on a single arc centered on the input shaft, which is a part of the input side member that rotates together with the input shaft, and a plurality of concave portions that rotate together with the output shaft. Claim 1 comprising a plurality of steel balls that are locked to a part of the output side member and rotate together with the output side member, and a pressing means that elastically presses the steel balls toward the recess. A tightening device for screws described in . (3) The impact applying mechanism is a part of the output side member that rotates together with the output shaft and is formed on a single circular arc centered on the output shaft, and a plurality of concave portions that rotate together with the input shaft. Claim 1 comprising a plurality of steel balls that are locked to a part of the input side member and rotate together with the input side member, and a pressing means that elastically presses the steel balls toward the recess. A tightening device for screws described in .