DE19528751C2 - Device for moving a mold clamping unit for use in blow molding machines - Google Patents

Description

The invention relates to a device for moving a Mold clamping unit in a blow molding machine according to the Preamble of claim 1.

In hollow blow molding machines, an intermediate form of one Extruder head discharged and through a blow mold grips and clamps, the two from a mold clamping unit held divided sections. After moving The intermediate form under a calibration unit becomes an air Blow nozzle inserted into the intermediate form to allow air into a Blow mold cavity to its expansion, making a mold receive part such as a container or the like will.

General is the mold clamping unit for the hollow body Blower system constructed so that the blow mold in a way that allows them to open and close, and the blow mold can be moved back and forth between the extruder and the Calibration unit. To increase production, will which adopted the double station system, the two on both Calibration unit located on the side of the head of the extruder ten, and two mold clamping units, which are so orders that they are from below the respective potash brier units are slidable below the extruder. If a mold clamping unit under the calibration unit po is positioned, the other mold clamping unit is below the Positioned extruder, and vice versa.

In a conventional form shifting system each becomes tension units Mold clamping unit ent by a hydraulic cylinder along the path of an oblique side of an imaginary one limb triangle moves. Another known system  become the mold clamping units using a servo motor and one Ball screw or a rack and pinion gear or tooth flat belt moves.

The displacement of the mold clamping units by the hydrau However, the cylindrical cylinder creates inconveniences like for example, an enlarged size of the system due to the requirement to arrange a hydraulic unit, hydraulic pipes, etc. as well as deterioration in order due to oil leakage, etc. On the other hand, the Displacement of the mold clamping units using the Servo motor and the ball screw or the rack and pinion drive or the flat toothed belt an offset of the intermediate Stop position and the bubble position due to Ver ball screw wear and toothed belt play, etc arise.

In addition, one cannot control the double station system Possible operation of the mold clamping units occur due to offsetting a determination of a servo motor encoder, of noise, etc. If such a disturbance occurs, the mold clamping units mutually, resulting in a serious malfunction.

DE-GM 19 90 057 is a device for manufacturing known from hollow bodies, in which the shape-holding plates of two pairs of handlebars are worn. These handlebar pairs are egg on the one hand at the upper edge of the mold holding plates and on the other hand articulated on the machine frame in such a way that the shape retention plates are moved on a circular path. To control the A conventional crank mechanism is used for movement Connecting rod is connected to the form retaining plates.

DE-OS 21 61 247 is a device for moving a mold clamping unit in a blow molding machine knows, in which the mold clamping unit by an electrical  Motor can be moved back and forth between an intermediate mold position and an air blowing position. There is a crank arm to convert the rotary motion of the electric motor into a Linear movement provided. In such devices for Manufacture of hollow bodies is a mold clamping unit that a blow mold carries back and forth between two positions moves. In one position, extruded material becomes raw introduced into the mold. The shape with the blank turns on finally moved into a blowing position, the blank is inflated to complete a hollow body. In at the positions must be the drive device, d. H. here is a cure Beltrieb, which is coupled to an electric motor will hold. To do this, the mass of the mold clamping unit must be reduced be braked. Especially with crank drives occur in particular the greatest acceleration in the direction of rotation reversal or braking forces. As a result, the An drive motor significantly loaded and on the other hand a precise Stopping after the braking phase is difficult, so that an accurate Positioning the mold clamping unit in an intermediate mold Stop position or a blowing position not exactly reproduced is cash. The quality of those to be produced suffers from this Hollow body.

The present invention is therefore based on the object in a device of the above type, the positioning improve the accuracy of the mold clamping unit and thus a more uniform quality of the moldings to be produced aim.

This task is egg in a device for moving ner mold clamping unit in a blow molding machine initially mentioned type solved according to the invention in that a shock absorber is provided which has a position displacement the intermediate mold stop position and the blowing position different.  

Advantageous further developments of the object of registration are set out in the subclaims.

In the following, the invention is illustrated by means of an embodiment game and associated drawings described in more detail. In the drawings show:

Figure 1 is a front view of a blow molding machine according to the embodiment.

Fig. 2 is a side view of the blow molding machine;

Fig. 3 is a view similar to Figure 1, showing a mold clamping unit-shifting device.

Fig. 4 is a fragmentary section of the Formaufspannein unit shifting device;

Fig. 5 shows a longitudinal section of a shock absorber;

. Fig. 6 is a similar to Figure 5 view of a crank arm with a shock absorbing function; and

Fig. 7 is a sketch for explaining the operation of the embodiment.

As shown in FIGS. 1 and 2, comprises a hollow body blowing system which is indicated generally by the reference numeral 1, a base 2 on which an extruder 3 is secured. A head 4 is suspended from the extruder 3 on its front side. Two calibration units 5 and two product removal devices 6 are arranged hanging on both sides of the head 4 , whereby a double station system is formed.

The head 4 has two discharge openings 4 a for extruding an intermediate mold, the position directly below the discharge openings 4 a corresponding to an intermediate mold holding position. In addition, each product removal device 6 comprises a vertically movable chuck or a suction pump 6 a.

Two mold clamping units 7 are movably arranged under the head 4 and the calibration units 5 , each mold clamping unit 7 holding a blow mold 8 in such a way that it can be opened and closed, which blow mold a pair of the discharge openings 4 a corresponding mouthpieces and a pair has associated mold cavities. The mold clamping unit 7 is attached to a Formaufspannein unit displacement device 9 , which is displaceable on two slide rails 10 , which are arranged on the base 2 at its Vorderab section.

As shown in FIGS . 1 and 4, the mold clamping device 9 is connected to a crank arm 12 via a holder 11 , which extends downwards, and the crank arm 12 is connected to a crank arm 13 , which in turn is connected to an output shaft 14 is connected. The output shaft 14 is coupled to a reduction gear 15 which is rotated and driven by an electric motor 16 such as a servo motor. In this way, the displacement device 9 can be moved back and forth when driving the electric motor 16 .

As shown in particular in FIGS. 3 and 4, the two slide rails 10 are attached in parallel horizontally to a frame 2 a, which is arranged on the base at a lower portion thereof. Two slide blocks 17 are in engagement with the slide rails 10 , each slide block 17 being coupled to the displacement device on the underside thereof.

One end of the crank arm 12 is rotatably attached to the holder 11 of the displacement device 9 at its lower end via a shaft 18 , and its other end is rotatably attached to the crank arm 13 via a shaft 19 . The crank rocker 13 is attached to the output shaft 14 , which is rotatably mounted on a bar attached to the base 2 plate 20 , wherein the output shaft 14 is connected to the reduction gear 15 , which in turn is connected to the electric motor 16 such as a servo motor is.

Thus, 1 and 3, when the right rocker arm 13 is rotated by driving the electric Mo gate 16 by 180 degrees in a clockwise direction, as seen from Figs. Obvious that Ver pusher 9 by the crank arm 12 under the Kali brier units shifted. 5 On the other hand, when the left rocker arm 13 is rotated 180 degrees clockwise, the shifter 9 is moved under the head 4 of the Extru ders 3 . Shock absorbers 25 , 26 are attached to the frame 2 a, with which the displacement devices 9 come into contact when they are moved under the head 4 or the calibration unit 5 to the very end.

As shown in particular in Fig. 3, the shock absorber 25 is attached to the frame 2 a and comes into contact with a contact plate 9 a, the cut on the slide block 17 and Seitenab the right hand shifter 9 is arranged so as to shift the right hand shifter 9 to prevent if this is moved under the head 4 to the very end. If the right-hand displacement device 9 is moved from below the head 4 to below the calibration unit 5 to the very end, a shock absorber 25 a comes into contact with a contact plate 9 b, which is arranged on a Seitenab section of the right-hand displacement device 9 , so one To prevent displacement of the right shifting device 9 .

On the other hand, the shock absorber 26 on the frame 2 a BEFE Stigt and comes into contact with a contact plate 9 c which is attached to the slide block stunning device 17 and side portions of the left shifters 9 are arranged, so as to prevent a shift of the left shifter 9, if this under the head 4 is moved to the very end. If the left displacement device 9 is moved from below the head 4 to below the calibration unit 5 to the very end, a shock absorber 26 a comes into contact with a contact plate 9 d, which is arranged on a side portion of the left displacement device 9 , so to prevent displacement of the left displacement device 9 .

As best seen in FIG. 1, that are in a position in which the displacement means 9 abuts the entspre sponding shock absorber 25, 26, the two of the Ver shifter 9 mouthpieces supported the blow mold 8 the two discharge ports 4 with respect to a. That is, a Mittelli never of the head 4 coincides with that of the blow mold 8 .

As shown in Fig. 5, the shock absorber 25 , 26 is attached to the frame 2 a via an elbow 27 which is vertically attached to a cylinder 28 . A rod 29 is axially movable through the cylinder 28 . A Schraubenfe the 30 is arranged around the rod 29 , and one end of the coil spring 30 abuts a pin 31 embedded in the rod 29 , and its other end abuts an inner end portion of the cylinder 28 , so that one Contact portion 32 disposed at one end of the rod 29 always protrudes from the cylinder 28 .

If the contact plate 9 a, 9 b comes into contact with the contact portion 32 , the coil spring 30 is therefore pressed together, thereby fulfilling the shock-absorbing function. The shock absorber 25 , 26 is not limited to the above type and may be a simpler type in which one end of the screw spring 30 is attached to the elbow 27 or one side of a plate spring is attached thereto.

As shown in Fig. 6, instead of the shock absorber 25 , 26, the crank arm 12 can be used with two divided sections 12 a, 12 b to fulfill the shock absorbing function. Specifically, this crank arm 12 is constructed so that a pot 33 is formed integrally with one section 12 a, whereas a flange 34 is integrally formed with the other section 12 b near its end, which can be moved back and forth into the Pot 33 is inserted. A Schraubenfe the 36 is placed between the pot 33 and the flange 34 , and a bolt 37 is arranged through the coil spring 36 . The bolt 37 is movably engaged with the flange 34 and is embedded in the pot 33 . In this case, a stop 38 for preventing displacement of the displacement device 9 is a simple stop and generally has a different construction from that shown in FIG. 5, but can be of the same type as that shown in FIG. 5.

As shown in FIG. 4, the mold clamping unit 7 comprises upper and lower shafts 40 , 40 which are arranged in parallel and horizontally, each being arranged so as to be axially displaceable by the displacement device 9 via bearings 41 . Mold mounting plates 42 are vertically coupled to the shanks 40 at both ends thereof, one of the mold mounting plates 42 serving to rotatably support a mold holding plate 44 via a hinge 43 . The mold holding plate 44 is slidably arranged through the upper shaft 40 to carry a section 8 a of the two divided sections of the blow mold 8 .

Similarly, a shape holding plate 44 a for supporting the other section 8 b of the two divided sections, which is opposite to the one section 8 a, is arranged through the upper shaft 40 . A holder 45 is attached to the mold holding plate 44 a. One end of a crank arm 46 is rotatably attached to the bracket 45 via a shaft 47 , and the other end is rotatably attached to a crank arm 59 via a shaft 48 . The crank arm 59 is rotatably supported by a shaft 50 on a sliding block 49 , which is arranged displaceably through the upper shaft 40 . The shaft 50 can be rotated and driven by an electric motor (not shown) attached to the slide block 49 .

One end of a crank arm 46 a is rotatably fastened by a shaft 51 to the crank arm 59 in the portion thereof which faces the shaft 48 in the diameter direction, and its other end is rotatably fastened to a cylinder 53 by a shaft 54 . The cylinder 53 can press plate springs 52 , which are held by the other of the Formaufspannplat th 42 . The plate springs 52 are fastened by a sleeve 55 which are arranged through central bores of the plate springs 52 . A rod 56 engaged with the sleeve 55 is arranged to protrude from a mounting plate 57 which is fixed to the platen 42 . The cylinder 53 can come into contact with the sleeve 55 . A pretensioner 58 is arranged for the sake of the sliding blocks 49 and is attached to the mold clamping-displacement device 9 .

Next, the operation of the above embodiment will be described. As explained with reference to FIG. 1, in a blow molding process, if the right or the left displacement device 9 is pushed ver under the corresponding calibration unit 5 , the other displacement device 9 can be moved under the head 4 to hold the intermediate shape, and under the corresponding calibration unit 5 who returned the. Then one of the displacement devices 9 is moved under the head 4 to hold the intermediate shape, and is returned under the corresponding calibration unit 5 .

A pair of electric motors 16 alternately reciprocate the rocker arms 13 within 180 degrees based on program control, and the shifting devices 9 can be alternately moved between the head 4 and the corresponding calibration unit 5 , which is a enables cyclical mass production of molded parts.

Further, as with reference to FIG. 7, as each elec tric motor on the basis of program control movement of the loading of the rocker arm 13 can freely control within 180 degrees, the blow mold 8 is stopped so that a center line A of a mold cavity 8 c is positioned so that it is offset against a center line B of the head 4 and the intermediate shape 61 discharged by it. So are a bottle 60 with a handle, as shown in FIG. 7 can be seen in the case of shaping, an intermediate form-retaining position c of the blow mold 8 against the center line A of the mold cavity 8 by a distance X is ver.

When the above blow mold is pushed ver 8 under the calibration unit 5, a center line C is brought to the calibrating unit 5 to coincide with a center line D of the mold cavity 8 c. So the blow mold 8 is moved back and forth only by a distance P, that is, the distance of the back and forth movement can be shortened, which leads to a shortened molding cycle. In addition, since a servo motor is used as the electric motor 16 , the route X can be changed easily. It should be noted that Fig. 7 shows an example in which the head 4 contains a single discharge opening 4 a and the calibration unit 5 comprises a single air blowing nozzle 5 a.

Claims (6)

1. Apparatus for moving a mold clamping unit ( 7 ) in a blow molding machine, in which the mold clamping unit ( 7 ) can be moved back and forth by an electric motor ( 16 ) between an intermediate mold holding position and a blowing position, and a crank arm ( 12 ) for converting the rotary movement of the electric motor ( 16 ) is provided in a linear movement, characterized in that a shock absorber ( 25 , 26 , 33 ) is provided which prevents a position offset of the intermediate mold holding position and the blowing position. 2. A device for shifting a Formaufspanneinheit according to claim 1, characterized in that the Formaufspannein integrated is attached (7) to a displacement device (9), wherein both sides of the side of the displacement device (9) contact plates (9 a, 9 b, 9 c, 9 d) are formed. 3. A device for moving a mold clamping unit according to claim 2, characterized in that the shock absorber ( 25 , 26 ) has a spring-damped contact section ( 32 ) which in the intermediate mold holding position and the Blasposi tion on one of the contact plates ( 9 a, 9 b , 9 c, 9 d). 4. A device for moving a mold clamping unit according to claim 2, characterized in that the shock absorber ( 33 ) is formed in the crank arm ( 12 ) so that the length of the cure arm ( 12 ) against the force of a spring device ( 36 ) is va riabel, and that stops ( 38 ) are provided which are in contact with the contact plates ( 9 a, 9 b, 9 c, 9 d) in the intermediate shape-holding position and the blowing position. 5. A device for moving a mold clamping unit according to one of claims 2 to 4, characterized in that a first end of the crank arm ( 12 ) rotatably on the displacement device ( 9 ) and a second end of the crank arm ( 12 ) rotatably on a crank arm ( 13 ) is mounted, the crank arm ( 13 ) being drivable by the electric motor. 6. A device for moving a mold clamping unit according to one of claims 1 to 5, characterized in that the hollow body blowing system has a first and a second mold clamping unit ( 7 ) that both on the right and on the left side of the blowing position, an intermediate mold holding position is arranged for extruding an intermediate mold, so that the mold clamping units can be moved alternately side by side from the intermediate mold holding position to the blowing position.