JP6731066B2 - Clamping device for injection molding machine - Google Patents

Description

The present invention relates to a clamping device for an injection molding machine.

In wax casting using a lost wax injection molding apparatus, a molten liquid resin material (wax) stored in a wax storage tank of the apparatus is supplied to a nozzle. The liquid wax melted from the tip of the nozzle is injected into the rubber mold held by the clamp device and solidified. This device is used for casting jewelry and the like. Since products such as jewelry have complicated shapes and the like, defects such as undercuts are likely to occur, and flexible mold materials such as silicone rubber or natural rubber are used.

FIG. 6 shows a clamp device 52 used in a conventional lost wax injection molding apparatus 50 as a typical example. Liquid wax is injected from the wax storage tank 51 of the injection molding device 50 into the rubber mold 53 through the nozzle 55. The rubber die 53 is, for example, divided into two upper and lower rubber die members 53a and 53b, and a side surface of the rubber die 53 has a dividing surface 53d. The dividing surface 53d has an arbitrary shape, but has a jagged shape so that it can be easily and uniquely combined. The rubber mold members 53a and 53b are properly and properly engaged with each other with the divided surfaces 53d being properly matched. A runner is formed in the rubber mold 53 in a state where the rubber mold members 53a and 53b are closely assembled. The runner is connected to the sprue 53c on the side surface of the rubber mold 53, and has a shape capable of receiving the tip of the nozzle 55. For example, the side surface of the tip of the nozzle 55 has a tapered truncated cone shape having a tapered surface, and the sprue 53c on the side surface of the rubber die 53 has a truncated cone hole shape along the tapered surface. When the surface of the tip of the nozzle 55 is properly inserted along the inner surface of the hole of the sprue 53c of the rubber die 53, the state where the rubber die members 53a and 53b are properly engaged is maintained.

On the other hand, in order to manufacture a high-quality wax molded product, it is necessary to inject an appropriate amount of liquid wax into all the runners from the thick runners to the thin runners. It is necessary to press the sprue 53c against the nozzle 55 in a state where the sprue 53c is pressed with an appropriate pressure in the mating direction. If improper force is applied to the rubber mold 53 or contact between the sprue 53c and the nozzle 55 is improper, an appropriate amount of liquid wax does not spread to all the runners or the wax leaks. Occurs. Therefore, the tip of the nozzle 55 needs to be accurately inserted into the sprue 53c of the rubber mold 53. To be inserted correctly means to align the horizontal and vertical central axes of the nozzle 55 and the sprue 53c of the rubber mold 53.

For example, when the nozzle 55 is inserted into the sprue 53c of the rubber die 53 in a positional relationship (FIG. 7A) such that the center line NZ ₀ of the nozzle 55 and the central axis 53e of the sprue 53c of the rubber die 53 are aligned (see FIG. 7A). 7B), the sprue 53c of the rubber die 53 properly receives the nozzle 55, and the force of separating the rubber die members 53a and 53b does not occur due to the separation of the dividing surface 53d. However, the central axis 53e and the deviation has a positional relationship of the sprue 53c centerline NZ ₀ and the rubber mold 53 of the nozzle 55 (FIG. 7C), when the nozzle 55 is inserted into the sprue 53c of the rubber mold 53 (Fig. 7D ), the nozzle 55 that has entered the sprue 53c of the rubber mold 53 may give a force for separating the divided surface 53d to the rubber mold members 53a, 53b, and may generate a force for separating the rubber mold members 53a, 53b from each other. is there. In particular, in the conventional clamping device, the center axis 53e of the sprue 53c of the rubber die 53 may be tilted with respect to the center line NZ _{0 of the} nozzle 55 to perform axis alignment. In the mode in which the rubber mold 53 is inclined with respect to the nozzle 55 as described above, when one of the rubber mold members 53a and 53b is pushed by the nozzle, a force that separates the rubber mold members 53a and 53b from each other is remarkable. become.

Rubber mold member 53a, in order not to generate a force of separating and 53b includes a center line NZ ₀ of nozzle 55, the central axis 53e of the sprue 53c is a parallel, and the vertical and horizontal position It is a match. However, generally, in the wax injection molding, a plurality of rubber molds 53 are used in order to improve the efficiency of the process by parallel work. At this time, the plurality of rubber molds 53 have different thicknesses depending on the design or due to manufacturing tolerances. Therefore, as a general rule, a centering step is required such that the center line NZ ₀ of the nozzle 55 and the center axis 53e of the sprue 53c of the rubber mold 53 are aligned with each other for each wax injection molding.

In this alignment step, even if the center line NZ ₀ of the nozzle 55 and the central axis 53e of the sprue 53c of the rubber mold 53 are displaced (FIG. 7C), depending on the entry of the nozzle 55 into the sprue 53c. Te, the central axis 53e of the sprue 53c of the rubber mold 53 is matched automatically in parallel to the center line NZ ₀ of nozzles 55, the nozzles 55 when entering along the sprue 53c of the rubber mold 53, the rubber mold 53 A clamp device that does not apply a load that separates the split surface 53d is required. For this purpose, it is necessary that the rubber mold 53 is movable in the direction perpendicular to the nozzle advancing direction, generally in the vertical direction, without resistance.

In order for the rubber mold 53 to be movable in the direction perpendicular to the nozzle advancing direction, generally in the vertical direction, without resistance, simply, as shown in FIG. 8, the rubber mold 53 is sandwiched between the pressing members 60a and 60b, and the pressing member is pressed. A device in which 60a and 60b are freely held by springs S1 and S2 is conceivable. However, in this device, since the synchronization between the springs S1 and S2 is not guaranteed, the pressing member 60a connected to the spring S1 and the pressing member 60b connected to the spring S2 are separated from each other by the rubber mold member 53a and the rubber mold member 53b. There is a problem in that the force for ensuring contact with can not be maintained constant.

On the other hand, a clamping device in an injection molding apparatus for injecting the wax from the sprue into a rubber mold having a sprue and a spout communicating with the spout via a nozzle from a tank storing the wax therein. The rubber mold is formed of at least two rubber mold members, and each of the at least two rubber mold members is assembled at a dividing surface to form the rubber mold. A bed having a mounting surface on which a mold is mounted and movable in a direction in which the nozzle extends; and the bed so that a weight is applied to the dividing surface of the rubber mold. This is solved by a clamp device that includes a pressing device that presses a rubber mold and an elastic device that can raise and lower the bed integrally with the pressing device.

According to the invention of the present application, the central axis of the nozzle and the central axis of the rubber mold are aligned with each other without causing a resistance force by the operation of aligning the nozzle of the injection molding device with the sprue position of the rubber mold.

It is the schematic diagram which showed embodiment of the centering concept of the clamp apparatus of this invention. It is the schematic diagram which showed embodiment of the centering concept of the clamp apparatus of this invention. It is a schematic diagram which showed the concept of the centering of the clamp apparatus of this invention. It is a schematic diagram which showed the concept of the centering of the clamp apparatus of this invention. It is a figure of a clamp device of one example which materialized a centering mechanism of the present invention. It is a figure of a clamp device of one example which materialized a centering mechanism of the present invention. It is a figure showing the relation between the tip of a nozzle and a rubber mold in an embodiment of the invention, and showing the state before a nozzle is inserted in a gate. It is a figure showing the relation between the tip of a nozzle and a rubber mold in an embodiment of the invention, and showing the state where a nozzle has begun to be inserted in a sprue. It is a figure showing the relation between the tip of a nozzle and a rubber mold in an embodiment of the invention, and shows the state of the latter half when a nozzle started to be inserted in a gate. It is a figure showing a relation between a tip part of a nozzle and a rubber mold in an embodiment of the invention, and shows a state where insertion of a nozzle into a sprue is completed. It is a figure of the clamp device of the conventional injection molding device. FIG. 5 is a schematic diagram showing a state in which the nozzle is separated from the rubber mold in a positional relationship such that the central axis of the nozzle and the central axis of the sprue of the rubber match. FIG. 6 is a schematic diagram showing a state in which the nozzle is joined to the rubber mold in a positional relationship such that the central axis of the duct line of the nozzle and the central axis of the sprue of the rubber mold coincide with each other. FIG. 5 is a schematic diagram showing a state in which the nozzle is separated from the rubber mold in a positional relationship in which the central axis of the nozzle duct and the central axis of the sprue of the rubber mold are displaced from each other. It is the schematic diagram which showed the state which the nozzle joined to the rubber type|mold in the positional relationship with which the central axis of the pipe line of a nozzle and the central axis of the sprue of a rubber type shift|deviate. It is the figure which conceptualized the general solution means.

An embodiment of a clamp device of the present invention will be described with reference to FIGS. 1A and 1B. 1A and 1B are views showing an embodiment of an alignment concept of a clamping device of the present invention. The clamp device according to the present invention is provided with a rubber mold 53 having a runner (broken line portion) and a sprue 53c communicating with the runner from a tank (not shown) for storing wax therein via a nozzle 55. It is used in an injection molding device that injects wax from the gate 53c. The rubber mold 53 is formed of at least two rubber mold members 53a and 53b, and is formed by assembling each of the at least two rubber mold members at the dividing surface. The sprue 53c of the rubber mold 53 has a sloped surface whose diameter decreases toward the inside of the rubber mold 53.

The clamp device has a mounting surface 61a on which the rubber mold 53 is mounted, and a bed 61 movable in the direction in which the nozzle 55 extends. The nozzle 55 has a tapered portion in the direction of the bed 61 along the direction in which the nozzle 55 extends, and a curved surface in contact with the slope of the sprue 53c of the rubber mold 53. When the nozzle 55 is inserted into the sprue 53c of the rubber die 53, the tip of the nozzle 55 contacts the slope of the sprue 53c of the rubber die 53.

The clamp device includes a pressing plate 62 and a pressing device 63 that presses the pressing plate 62 against the bed 61. The rubber mold 53 is arranged between the bed 61 and the pressing plate 62, and the pressing device 62 moves the pressing plate 62 with respect to the bed 61 to press the rubber mold 53. Weight is added.

The bed 61 is coupled to the elastic device S3, and the elastic device S3 has an elastic force capable of moving up and down the bed 61 without resistance. The elastic device S3 is a spring, a bellows, or the like. The elastic force capable of moving up and down without resistance is balanced against the weight of the bed 61 and the pressing device 63 integrated, and the bed 61 can be maintained in a neutral state without moving down or rising. It means that the elastic force is in a state and can move up and down without resistance. Substantially, it means that the elastic coefficient of the elastic device S3 is close to zero. FIG. 2A shows a state in which the nozzle 55 is inserted into the sprue 53c of the rubber mold 53 and fitted into the sprue 53c. In this way, the nozzle 55 relatively moves from the nozzle position 55a to the nozzle position 55b along the slope that is the inner wall surface of the gate 53c of the rubber mold 53 until the nozzle 55 is fitted into the gate 53c.

As shown here, the elastic force of the elastic device S3 is the vertical direction of the force Fp that pushes the inclined surface of the inner wall of the sprue 53c of the rubber mold 53 when the nozzle 55 is inserted into the sprue 53c of the rubber mold 53. Component Fpv and the component force component Ffv in the vertical direction of the frictional force Ff that the nozzle 55 receives from the slope of the sprue 53c of the rubber die 53 are almost equal to or smaller than the force component (Fpv-Ffv). Is set as follows. With this setting, the bed 61 can be raised and lowered without resistance.

Further, FIG. 2B shows that when the nozzle 55 is inserted into the sprue 53c of the rubber mold 53, the initial position of the nozzle 55 with respect to the sprue 53c of the rubber mold 53 is the elastic force depending on the difference between the short distance position 55c and the long distance position 55d. It is the figure which showed the difference. As shown in FIG. 2B, when the initial position of the nozzle 55 is the short distance position 55c, the distance between the center line NZ ₀ and the center line O of the sprue 53c of the rubber mold 53 is x1, and the initial position of the nozzle 55 is long. It is assumed that the distance between the center line NZ ₀ and the center line O of the sprue 53c of the rubber mold 53 at the distance position 55d is x2. x2 is greater than x1. In this case, the magnitude of the elastic force of the elastic device S3 is generally proportional to the distance between the center line NZ ₀ of the nozzle 55 and the center line O of the sprue 53c of the rubber mold 53. For example, when the spring or bellows is the elastic device S3, it is proportional to the elastic coefficient k of the elastic device S3. Therefore, when the distance between the center line NZ ₀ of the nozzle 55 and the center line O of the sprue 53c of the rubber mold 53 is x1, it is k·x1, and when the distance is x2, it is k·x2. Since x2 is larger than x1, the further away from the center line O, the greater the elastic force of the elastic device S3, and a large force is required to cancel this elastic force.

That is, the elastic force increases as the center line NZ ₀ of the nozzle 55 moves away from the center line O of the sprue 53 c of the rubber mold 53. Therefore, in the design of the elastic device S3, it becomes difficult to set an elastic force capable of moving up and down without resistance in a wide range. In the clamp device, it is preferable that the thickness of the rubber mold 53 can be freely set. Therefore, in order to set an elastic force that allows lifting and lowering without resistance in a wide range, in addition to the elastic device S3 as shown in FIG. The lifting device S4 can be further arranged. As shown in FIG. 1B, the preliminary elevating device S4 is arranged, and the position of the elastic device S3 is previously raised by the preliminary elevating device S4 so that the initial position of the nozzle 55 is always close to the center line O of the sprue 53c of the rubber mold 53. Lower it. That way, regardless of the thickness of the rubber mold 53, it is possible to the nozzle 55 from the center line NZ ₀ closer to the center line O of the sprue 53c of the rubber mold 53 and becomes, by the elastic force of the elastic device from S3 therefrom It is possible to move up and down without resistance. Further, a position detecting device 64 such as a proximity sensor or a potentiometer is arranged in the clamp device so that the position of the bed 61 can be detected, for example. The preliminary lifting device S4 is operated according to the output, and the bed 61 is moved so that the initial position of the nozzle 55 is close to the center line O of the gate 53c that can be lifted without resistance by the elastic force of the elastic device S3. ..

(Example 1)
Then, Example 1 to which the above-described embodiment is specifically applied will be described with reference to FIG. FIG. 3 shows the clamp device 1a according to the first embodiment. The clamp device 1a is the same in that it is applied as a part of the conventional injection molding device 50 of FIG. The nozzle 5 is a part of the injection molding device 50 shown in FIG. The rubber mold 3 is also similar to that used in the conventional injection molding device 50 shown in FIG. Example 1 corresponds to an example in which the elastic device S3 is the elastic device 7 that is a spring and the preliminary lifting device S4 is the pneumatic cylinder 12 in the above-described embodiment. The function of Example 1 is the same as that described in the embodiment.

The clamp device 1 a includes a pressing plate 2 and a bed 4 arranged to face the pressing plate 2. The rubber mold 3 has a first surface 3a and a second surface 3b parallel to the first surface 3a. A side surface 3c is formed between the first surface 3a and the second surface 3b. The rubber mold 3 is typically a rectangular parallelepiped having a flat plate shape or a cylindrical shape. A runner is bored inside the rubber mold 3, and a runner 3d fluidly connected to the runner is arranged on the side surface 3c. 5A to 5D show the positional relationship between the nozzle 5 of the injection molding device and the sprue 3d of the rubber mold 3. The sprue 3d is a tapered hole from the side surface of the rubber mold 3 toward the inside of the rubber mold 3. The nozzle 5 is tapered toward the tip of the nozzle 5. The opening angle α of the tip of the nozzle 5 is smaller than the opening angle β of the sprue 3d. The tip of the nozzle 5 has a spherical shape. Therefore, when the nozzle 5 is inserted into the sprue 3d, the spherical portion of the nozzle 5 appropriately contacts the sprue 3d.

The bed 4 has a horizontal and flat mounting surface 4a, and the mounting surface 4a supports the rubber mold 3 in a state where the second surface 3b of the rubber mold 3 is in contact therewith. The rubber mold 3 faces upward when facing the pressing plate 2 while being placed on the placement surface 4a. The pressing plate 2 can be moved up and down by a hydraulic cylinder 6 which is a pressing device. The pressing plate 2 can come into surface contact with the first surface 3a. As a result, with the rubber die 3 placed on the placing surface 4a, the pressing plate 2 presses the first surface 3a, and the rubber die 3 is pressed between the first surface 3a and the second surface 3b. Apply pressure to.

The nozzle 5 extends horizontally from the injection molding device. The bed 4 of the clamping device 1a has a translation device 8. The translation device 8 moves the bed 4 of the clamp device 1a together with the pressing plate 2 and the hydraulic cylinder 6 along the direction in which the nozzle extends so as to come into contact with the nozzle 5 or away from the nozzle 5. You can That is, the bed 4 is brought into contact with the nozzle 5 or separated from the nozzle 5 along the direction in which the nozzle extends in a state where pressure is applied to the rubber mold 3 by the pressing plate 2 by the translation device 8. Move to.

Further, an elastic device 7 is arranged below the bed 4 of the clamp device 1a. In the first embodiment, a helical spring is used as the elastic device 7. The elastic device 7 is swingable in a direction perpendicular to the direction in which the nozzle 5 extends, integrally with the pressing device and the pressing plate 2. The elastic device 7 is such that, with the rubber die 3 placed on the placing surface 4a, it is repelled by a light force that can be pushed down by a human hand, and at least the tip of the nozzle 5 has an opening diameter of the spout 3d. It has an elastic force capable of swinging within the range.

Next, with reference to FIGS. 5A to 5D, the relationship between the rubber mold 3 and the nozzle when the clamp device 1a is used will be described. A predetermined pressure is applied to the rubber mold 3 by the pressing plate 2 on the first surface 3a and the second surface 3b. With this pressure applied, the bed 4 is balanced by the elastic device 7 so that the tip of the nozzle 5 can swing within the range of the opening diameter of the sprue 3d regardless of the weight of the rubber mold 3. There is.

In this state, the translation device 8 brings the bed 4 closer to the nozzle. Then, as the bed 4 moves, the tip of the nozzle 5 is inserted into the opening of the sprue 3d of the rubber mold 3. At this time, the spherical portion at the tip of the nozzle 5 contacts the wall surface portion of the sprue 3d. When the bed 4 is brought closer to the nozzle 5 by the translation device 8, the spherical portion at the tip of the nozzle 5 pushes the wall surface of the sprue 3d, and the rubber mold 3 is pushed down together with the bed 4. Then, as the bed 4 approaches the direction of the nozzle 5, the spherical portion at the tip of the nozzle 5 relatively moves toward the center of the gate 3d along the wall surface of the gate 3d, and finally the nozzle 5 The center of the pipe line at the tip and the central axis of the pipe line of the sprue 3d are aligned in parallel. As described in the embodiment, this is because the elastic force of the elastic device 7 can be ignored when the nozzle 5 and the wall surface of the sprue 3d of the rubber mold 3 come into contact with each other. This is because the frictional force received by the nozzle 5 from the wall surface of the sprue 3d of the rubber mold 3 is sufficiently small with respect to the force pressing the mold 3.

As a result, in the clamp device 1a, when the bed 4 on which the rubber mold 3 is placed is brought close to the nozzle 5 together with the pressing plate 2 that presses the rubber mold 3, the bed 4 has an elastic device 7 and has no resistance. Since it can be swung by a weak force, the contact point between the nozzle 5 and the sprue 3d moves along the wall surface of the sprue 3d toward the central axis of the sprue 3d without resistance along the inclination of the nozzle 5, The center axis of the nozzle 5 and the center axis of the sprue 3d can be aligned. Therefore, when the step of connecting the nozzle 5 and the sprue 3d of the rubber mold 3 is performed by using the clamp device 1a of the present invention, the center of the duct at the tip of the nozzle 5 and the center of the duct of the sprue 3d are used. The aligning process with can be realized at the same time.

Further, as described in the above embodiment, the bed 4 is moved up and down by the pneumatic cylinder 12 which is the preliminary elevating device so that the central axis of the nozzle 5 and the central axis of the sprue 3d can be adjusted so as to substantially coincide with each other. Become. In particular, the bed 4 is moved up and down by adjusting the pressure in the pneumatic cylinder 12 to a position where the tip of the nozzle 5 is positioned at the opening portion of the gate 3d on the side surface of the rubber mold 3 in the vertical direction at the minimum. Adjust the bed position roughly. This ensures that the tip of the nozzle 5 is balanced so as to be swingable within the range of the opening diameter of the sprue 3d. Further, in the vertical direction, the bed 4 is moved up and down by the pneumatic cylinder 12 to a position where the tip of the nozzle 5 is located at the opening portion of the sprue 3d on the side surface of the rubber mold 3, so that the bed position can be adjusted. It is possible to roughly adjust to the place where the reaction force due to the elastic force is the smallest. Further, a potentiometer 11 is arranged as a position detecting device to detect the vertical position of the bed 4, so that the tip of the nozzle 5 is swung by the pneumatic cylinder 12 within the range of the opening diameter of the sprue 3d. It can be adjusted automatically. The potentiometer 11 detects height information on the circuit board and operates the pneumatic cylinder 12 to move the bed 4 up and down according to the height information so that the center axis of the nozzle 5 and the center axis of the sprue 3d are substantially in advance. Adjust to match.

(Example 2)
Then, Example 2 to which the above-described embodiment is specifically applied will be described with reference to FIG. FIG. 4 shows a clamp device 1b according to the second embodiment. The clamp device 1b is almost the same as the clamp device 1a of the first embodiment. Therefore, different parts will be described here. The clamp device 1b of Example 2 corresponds to an example in which the bellows 10 is adopted as the elastic device S3 in the above-described embodiment. Theoretically, the bellows 10 has an elastic coefficient of almost zero, and it is easier to set the elastic coefficient than a helical spring having a finite elastic coefficient determined by the material and the geometrical shape. It will be very advantageous to you. The function of the second embodiment is the same as that described in the first embodiment, and the bellows 10 is adopted as the elastic device S3, but the same operation as in the first embodiment is performed.

INDUSTRIAL APPLICABILITY The present invention can be applied as a clamp device of an injection molding device represented by a lost wax casting device.

1,52 Clamping device 2,62 Pressing plate 3,53 Rubber type 4,61 Bed 5,55 Nozzle 6 Hydraulic cylinder 7, S3 Elastic device 8 Translation device 10 Bellows 11 Potentiometer 12 Pneumatic cylinder 63 Pressing device

Claims (3)

Via nozzles from the tank for storing the wax inside the wax from said sprue in a rubber mold having the sprue and having a slope such as diameter toward the inside and communicating with the runner and the runner inside is reduced A clamp device in an injection molding device for injecting,
The rubber mold is formed of at least two rubber-type members, each of the rubber mold member to form the rubber mold by mating division surfaces,
The clamp device is
A bed having a mounting surface on which the rubber mold is mounted, the bed movable in a direction in which the nozzle extends,
A pressing device for pressing the rubber mold so as to the bed, weight is added to the divided surface of the rubber mold,
A bellows having an elastic coefficient of substantially zero and raising and lowering the bed integrally with the pressing device;
A clamp device having a position detection device and a preliminary lifting device,
The bellows includes a vertical component of force of the force of the nozzle pressing the inclined surface of the sprue of the rubber mold when the nozzle is inserted into the sprue of the rubber mold and the nozzle of the rubber mold. The difference between the vertical component force component of the frictional force received from the slope of the sprue, and the elastic force that is set to be substantially the same or smaller than that, it is possible to lift and lower the bed without resistance,
The position detecting device detects the position of the bed, and the preliminary elevating device elevates and lowers the bed according to the position of the bed detected by the position detecting device so that the position of the bed is always the tip of the nozzle. swingably der Ru clamping device within the opening diameter of the sprue. The clamp device according to claim 1, wherein
The bed is a clamp device in which the rubber mold is movable in the direction of the nozzle together with the bed and the pressing device. The clamp device according to claim 2, wherein
The said nozzle is a clamp apparatus which has a taper-shaped part in the direction of the said bed along the direction which the said nozzle extends, and the curved surface which contacts the said slope.

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