JPS5940609B2 - Deburring device for plastic hollow molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for cutting off the bottom burr of a molded bottle in the process of manufacturing a blow molded bottle from a plastic tubular Paryline, and particularly for a biaxial stretch blow molding method using a cold Paryline method. This is an effective device in some cases.

In recent years, in order to make more effective use of the original characteristics of the resin, the stretching orientation has been strengthened, and in order to improve the container's drop strength, transparency, gloss, and other qualities, Parilynn has been rapidly cooled, then reheated to the stretching temperature range and stretched in the longitudinal direction. The so-called biaxial stretch blow molding method, which involves blow molding, has been used to great effect in the molding of vinylidene chloride containers and polypropylene containers. In this molding method, conventional injection molding or other methods are used to first make a bottomed parylin, then reheat it and stretch it lengthwise with a core and blow mold it, but in most cases it is first extruded into a pipe shape. The formed product is reheated to the stretching temperature range, the upper and lower ends of the pipe are grasped, and the pipe is stretched in the longitudinal direction within a range with an elastic recovery rate of 70% or more, and the stretched part is sandwiched between molds and blow molded. many. Therefore, the molded article has unnecessary parts attached to it at one or both ends. In the case of melt blowing, methods are used such as cutting off the material with the corner of the mold or cutting it off easily in a subsequent process and cutting it off after it has cooled. However, in the case of biaxial stretch blow molding, internal stress is strong in the longitudinal direction when longitudinally stretched, so if you try to cut it with a corner of the mold or a knife fixed to the mold, it will break before the parilyn is grasped at the end of the mold. This will cause the crimp to shrink, resulting in poor crimping, and a portion will break, causing the crimping part to shift inward, making the crimping unstable. As a method to prevent this, a method has been considered in which the Parylin is crimped with a mold and then a separate knife is moved to cut off the excess material. In order to use this method, a separate drive is required to open and close the mold and to move the cutter, making the structure extremely complicated. On the other hand, the present invention utilizes the operation of opening and closing the mold by a single air cylinder to press the Parylin to a certain extent and then operate the cutter, thereby ensuring reliable crimping and removal of excess thickness without the need for a separate drive. This device is characterized by its ability to perform ablation.

This device has a mold opening/closing mechanism as shown in the figure. In other words, the arm to which the mold is attached rotates around one fulcrum. The force that gives this rotation is generated by a U-shaped mold clamping frame connected from the outside of the mold via a pin connecting plate, which opens and closes the mold by moving in and out.
When the mold has finished tightening, it is fixed with a toggle so that the mold will not open even if internal pressure is applied. On the other hand, in a part of the mold where the excess metal is removed, a blade on one side is designed to be able to slide a few millimeters, and normally it is retracted by a spring, but due to external force it protrudes a few millimeters and engages with the fixed blade to cut out the excess metal. It is designed so that the part can be removed. With the mold clamping mechanism having such a structure, when the longitudinally stretched parison is brought to the center of the mold and the mold clamping frame is advanced, the mold clamps at the ends and pinches the parison to some extent.
Then, by moving it further forward, force is applied to the mold mating surface,
The mold is tightened until the gap between its outer edges is less than a few millimeters, and then, as the mold is further tightened, this final movement of the mold clamping frame is used to advance the knife and cut out the excess material. .
By the time the knife is moved, the parison is already pressed by the mold, so even if it is cut by the knife, there will be no crimping failure. In order to stabilize this method, this device takes the following two considerations.

The first is to use compressed air to open and close the mold, and when the valve opens with an electrical signal and air enters the cylinder, there is little resistance until the parison is sandwiched between the molds, and the pressure inside the cylinder is low. It operates in a short time because it moves even if the cylinder does not reach a predetermined pressure, but the resistance increases after the parison is pressed down, so it operates only after the pressure inside the cylinder rises. Therefore, there will be some time delay. This delay can be adjusted by adjusting the entrance and exit path of the compressed air into the air cylinder, and this time delay is effective in crimping the parison and then cutting it off. The second is the mold clamping mechanism. Even if the mold clamping frame moves at a constant speed, the speed at which the mold closes is initially fast and then gradually slows down due to its structure.Especially at the final tightening, even if the mold is almost closed, there is still a distance that the mold clamping frame has to travel. This last movement can be used to push the knife. Therefore, it is possible to give the effect of pressing the parison to some extent with the mold and then moving the cutter. As mentioned above, by combining the mold clamping method using compressed air, the mold clamping method using a toggle structure, and a movable cutter, it is possible to create a parison with internal stress in the longitudinal direction, similar to biaxial stretch blow molding, by simply applying a mold clamping action. However, it is a deburring device that can reliably perform crimping and remove excess material.

Preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings.

First, the movement of the mold clamping device shown in the figure will be described. An air cylinder 1 operated by compressed air is attached to the frame 2, and a piston 3 moves in and out. A mold clamping frame 5 is attached to the tip of this piston 3 and slides on a slide shaft 4. On the other hand, two fulcrum shafts 11 are fixed to a part of the pedestal 2 at the top and bottom, and the mold mounting plate 13 can be rotated by engaging with these. Since the mold mounting plate 13 and the mold clamping frame 5 are connected by the pins 6, 8 and the connecting plate 7, when the mold clamping frame 5 is advanced by the air cylinder 1, it will be in the state shown in FIG. Then, the situation will be as shown in the figure. A mold for molding is attached to this rotatable mold mounting plate 13 as shown in FIGS. 3 to 5. First, two sets of upper and lower split mold bodies 10 are attached to the girder 19, and a blow molding nozzle 1 is installed in the center thereof.
2 is installed. Each of the mold bodies 10 has a bottom mold 14.
, 14' are attached to this mold body 10 and bottom mold 14.
, 14' are called split molds. A fixed blade 26 is fixed to the bottom mold 14 with bolts 27, and a movable blade 22 that can slide along the groove is attached to the bottom mold 14', and this is lifted up by a holding plate 24 which is secured with screws 25. The constantly movable blade 22 is held back by the compression spring 23, as shown in FIG. 6A. When pushed by the blade pusher 20, the movable blade 22 slides against the compression spring 23, moves forward, and becomes engaged as shown in Figure 6. This movement is caused by the head of the push bolt 19, which is tightened by the fixing nut 18 attached to the tip of the push arm 16, which is fixed to the connecting plate 7 with a bolt 17, and the knife pusher 20 is moved to the pin 21. The movable blade 22 is pushed by rotating around the center. Therefore, the moving distance of the cutter is adjusted using the push bolt 19, and the fixing nut 18 is used to prevent loosening. In a mold clamping device for a mold having such a structure, first, as shown in FIG. 2, both ends of the parison 29 are gripped by chucks 28, and when the longitudinally stretched parison 29 is at the opening position in FIG. Although not shown in the diagram, the air cylinder 1 is
When compressed air is sent to the state shown in Fig. 5, there is little resistance, so even if the air pressure inside the cylinder is low, the piston 3 moves forward at a high speed, and the piston 3 pushes the mold clamping frame 5, causing the mold to move to the fifth position. It will look like the figure. At this time, the state of the blade part is as shown in Figure 6A, the mold is almost closed and the parison 29 is almost crimped, but when it reaches this position, the mold is closed. Air cylinder 1 because the force increases the resistance.
Only when the internal pressure approaches a predetermined pressure does the connecting plate 7 become perpendicular between the mold and mold clamping frame 5 as shown in Figure 3, so that the mold will not open even if internal pressure is applied during blow molding. It will become.
At this time, the state of the blade is as shown in the opening in Figure 6, and the movable blade 22 moves from A to B in Figure 6 to cut off the excess thickness. Even if the piston 3 moves at a constant speed and the mold clamping frame 5 is pushed, the closing speed of the mold is fast at first, but slows down as it approaches the state shown in Figure 5, and the mold closes almost completely in the state shown in Figure 5. From FIG. 5 to FIG. 3, the mold is tightened and the movable blade 22 is pushed. Therefore, these two actions produce the effect that after the parison 29 is crimped, the knife is pressed and the excess thickness is cut off. As can be seen from the above embodiments, the present invention effectively utilizes a toggle-type mold clamping mechanism that incorporates a cutter into the mold and uses one air cylinder in a mold clamping device for biaxial stretch blow molding. This method is very effective industrially because it is designed to be able to crimp a part of a parison that has internal stress in the longitudinal direction and simultaneously remove the excess thickness.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a mold clamping device for sandwiching and blow-molding a longitudinally stretched parison between molds, in which A shows the closed state and the mouth is open. Figure 2 is an elevation view, Figure 3 is a detailed view of the part where the blade is attached to the mold, Figure 4 is a cross-sectional view of section A, and Figure 5 is the state before pressing the blade. In the figure, Figure 6 is the same as Figure 5 and 3.
The details of the crimping and cutter portion in the state shown in the figure are shown, and the A figure corresponds to FIG. 5, and the open figure corresponds to FIG. 3. 1: Air cylinder 1, 2: Frame, 3: Piston, 5: Clamping frame, 6
and 8: pin, 7: connecting plate, 9: girder 10: mold body, 11: fulcrum pin, 12: nozzle, 13: mold mounting plate, 14 and 14': bottom mold, 16: push arm, 19: Push bolt, 20: Blade pusher, 22: Moving blade, 23: Compression spring, 24: Holding plate, 26: Fixed blade, 28: Chuck, 29
:Parison.

Claims (1)

[Claims] 1 In a biaxial stretch blow molding machine having a mold opening/closing device with a toggle mechanism operated by an air cylinder, there is a fixed blade fixed to one of the split molds, and a mold that engages with the fixed blade in the other mold. A slidingly built-in movable blade is provided, a push arm is fixed to the mold operation connecting plate on the movable blade side, and a knife pusher is provided between the movable blade and the push arm, and the action of the air cylinder is In the process of pushing the mold clamping frame and closing the mold, after the opening distance of the mold becomes less than a few millimeters between the outer end surfaces, the movable blade is pushed by the pushing arm fixed to the connecting plate and the knife pushing. A deburring device for a biaxially stretched hollow molded product, which is configured so that the excess thickness of the parison is removed while both ends of the parison are securely sandwiched between the molds.