JP7509633B2 - Molding machine - Google Patents

Description

The present invention relates to a molding machine equipped with an ejector device.

Conventionally, molding machines have been known that include a mold clamping device that opens, closes, and clamps the mold, an injection device that injects molding material into the cavity of the clamped mold, and an ejector device that ejects a molded product from the open mold (see, for example, Patent Document 1).

The ejector device described in Patent Document 1 moves an ejector plate back and forth by driving a pair of ball screws with a servo motor. This causes the ejector pins supported by the ejector plate to protrude from and retract into the inner surface of the mold.

JP 2013-163365 A

However, in a configuration in which the ejector plate is advanced and retreated by a pair of ball screws, even a slight assembly error (e.g., adjusting the parallelism of the pair of ball screws) places a moment load on the ball screws. If the molding machine continues to operate in this state, this could result in damage to the ball screws and a shortened lifespan of the ejector device.

The present invention was made to solve these problems with the conventional technology, and its purpose is to provide a technology that extends the life of an ejector device in a molding machine equipped with an ejector device.

In order to solve the above-mentioned problems, the present invention provides a molding machine including a clamping device that opens/closes and clamps a fixed-side mold and a movable-side mold by moving a movable die plate that supports a movable-side mold toward and away from a fixed die plate that supports a fixed-side mold, an injection device that injects a measured amount of molding material into cavities of the clamped fixed-side mold and the movable-side mold, and an ejector device that ejects a molded product from the opened movable-side mold, the ejector device comprising an ejector motor, a rotating nut that is rotated by the driving force of the ejector motor, and a ball screw shaft that is screwed into the rotating nut and moves forward and backward as the rotating nut rotates. the pin support portion comprises a plate that supports the ejector pins at a plurality of positions including the center of its surface, a pair of legs that protrude from the rear surface of the plate at positions that are point-symmetrical with respect to the center of the plate and shifted in the vertical direction, and a connection portion that connects the protruding ends of the pair of legs together at a position spaced from the plate in the extension direction of the ball screw shaft , and supports the ball screw shaft at a position corresponding to the center of the plate.

This invention makes it possible to extend the life of the ejector device.

FIG. 1 is a side view of an injection molding machine according to an embodiment of the present invention. FIG. 2 is an enlarged front view of the periphery of the ejector device. FIG. 2 is an enlarged plan view of the periphery of the ejector device. FIG. 4 is a perspective view of the pin support portion as viewed from the front surface side. FIG. 4 is a perspective view of the pin support portion as viewed from the rear surface side. FIG.

The injection molding machine 10 according to the present invention will be described below with reference to the drawings. The injection molding machine 10 is a device that injects a measured amount of plasticized resin (molding material) into a mold to form an injection molded product. However, a specific example of the molding machine is not limited to the injection molding machine 10, and may be a die-casting machine that injects molten metal (molding material) into a mold to form a molded product.

Figure 1 is a side view of an injection molding machine 10 according to this embodiment. As shown in Figure 1, the injection molding machine 10 mainly comprises an operation panel 11, a mold clamping device 20, an injection device 30, and an ejector device 40. In this specification, the side facing the operation panel 11 is referred to as the "front side (front)" of the injection molding machine 10, and when viewed from the front side of the injection molding machine 10, the side on which the mold clamping device 20 is provided is referred to as the "left side," and the side on which the injection device 30 is provided is referred to as the "right side."

The operation panel 11 includes a display that shows information (text, images, videos) to the operator, and operation buttons (push buttons, touch panel) that accept instructions from the operator. The side facing the operation panel 11 refers to the side around the injection molding machine 10 where the information displayed on the display can be seen.

The clamping device 20 opens, closes, and clamps the mold 21. Specifically, the clamping device 20 mainly comprises a fixed die plate 23 that supports the fixed mold 22, and a movable die plate 25 that supports the movable mold 24. The fixed mold 22 and the movable mold 24 are supported so as to face each other in the left-right direction (horizontal direction) of the injection molding machine 10.

The movable die plate 25 moves left and right along the tie bars 27 as the driving force of a die opening/closing motor (not shown) is transmitted through a toggle link mechanism 26. When the movable die plate 25 moves leftward, the fixed die 22 and the movable die 24 move apart. On the other hand, when the movable die plate 25 moves rightward, the fixed die 22 and the movable die 24 come into contact with each other, forming a cavity (internal space) inside the die 21. Then, when further pressure is applied in a direction that moves the movable die plate 25 rightward, the fixed die 22 and the movable die 24 are clamped.

The injection device 30 plasticizes, measures, and injects the molding material. In this embodiment, the injection device 30 is arranged horizontally separated from the mold clamping device 20 (to the right of the mold clamping device 20). The injection device 30 mainly comprises a heating cylinder 31, a screw 32, a hopper 33, and a hopper block 34.

The heating cylinder 31 is a cylindrical member that extends in the left-right direction of the injection molding machine 10. The heating cylinder 31 mainly includes a screw passage 35 and a nozzle 36. In addition, a band heater (not shown) that heats the heating cylinder 31 is attached to the outer circumferential surface of the heating cylinder 31.

The screw passage 35 is a linear space that extends axially (longitudinal) inside the heating cylinder 31. The screw passage 35 is connected to the outside of the heating cylinder 31 through a nozzle 36 provided at the tip of the heating cylinder 31. In other words, the screw passage 35 is a space that extends axially from the nozzle 36.

The screw 32 is a cylindrical member. A spiral groove is formed on the outer circumferential surface of the screw 32. The screw 32 is housed in the internal space of the heating cylinder 31 in a state in which it can move left and right (hereinafter referred to as "advance and retreat") and rotate in the injection molding machine 10. The screw 32 advances and retreats when the driving force of an injection motor (not shown) is transmitted to it, and rotates when the driving force of a metering motor (not shown) is transmitted to it.

The hopper 33 is a funnel-shaped member that stores the raw molding material. The hopper block 34 is a member that supports the heating cylinder 31 and the hopper 33. The molding material stored in the hopper 33 is supplied to the screw passage 35 of the heating cylinder 31 through an opening provided at the bottom end.

The ejector device 40 is a device that ejects the injection molded product from the open movable die 24. The ejector device 40 is supported by the movable die plate 25 and moves forward and backward together with the movable die plate 25. The ejector device 40 also causes the ejector pins 47 (see Figures 2 and 3) to appear and disappear from the inner surface of the open movable die 24. This causes the injection molded product to be released from the movable die 24.

Figure 2 is an enlarged front view of the periphery of the ejector device 40. Figure 3 is an enlarged plan view of the periphery of the ejector device 40. As shown in Figures 2 and 3, the ejector device 40 mainly includes an ejector motor 41, a rotating nut 42, a driving force transmission mechanism 43, a ball screw shaft 44, a pin support portion 45, a pair of guide rods 46, and a plurality of ejector pins 47.

The ejector motor 41 rotates forward and backward according to the control of a control device (not shown) of the injection molding machine 10. The rotating nut 42 is rotatably supported by a ball bearing on the movable die plate 25. The rotating nut 42 rotates as the rotational driving force of the ejector motor 41 is transmitted through the driving force transmission mechanism 43.

The driving force transmission mechanism 43 is composed of a gear 43a that rotates integrally with the output shaft of the ejector motor 41, a gear 43b that rotates integrally with the rotating nut 42, and an endless annular belt 43c that is stretched over the gears 43a and 43b. However, the specific configuration of the driving force transmission mechanism 43 is not limited to the above example, and may be a gear train that meshes with each other or a chain drive.

The ball screw shaft 44 is screwed into the rotating nut 42 and extends in the left-right direction. The ball screw shaft 44 advances and retreats as the rotating nut 42 rotates. More specifically, the ball screw shaft 44 advances (moves to the right) when the ejector motor 41 rotates forward. The ball screw shaft 44 retreats (moves to the left) when the ejector motor 41 rotates reversely.

The ball screw shaft 44 also has a lubricating oil supply port 44a, an axial internal passage 44b, and a radial internal passage 44c. The lubricating oil supply port 44a is a portion to which a hose for supplying lubricating oil is attached. The axial internal passage 44b is an internal passage extending axially from the lubricating oil supply port 44a inside the ball screw shaft 44. The radial internal passage 44c is an internal passage extending radially from the axial internal passage 44b of the ball screw shaft 44 and opening on the outer circumferential surface of the ball screw shaft 44. The radial internal passage 44c is disposed in a position facing the rotating nut 42. That is, the lubricating oil supplied through the lubricating oil supply port 44a is supplied to the rotating nut 42 through the axial internal passage 44b and the radial internal passage 44c.

The pin support portion 45 is fixed to the tip of the ball screw shaft 44. A pair of guide rods 46 (only one of which is shown in FIG. 3 ) that are supported by the movable die plate 25 and extend in the left-right direction are inserted into the pin support portion 45. The pin support portion 45 also supports a number of ejector pins 47. The pin support portion 45 advances and retreats together with the ball screw shaft 44 while being guided by the pair of guide rods 46. This causes the multiple ejector pins 47 to appear and disappear from the inner surface of the movable die 24.

Figure 4 is a perspective view of the pin support portion 45 as viewed from the front side. Figure 5 is a perspective view of the pin support portion 45 as viewed from the back side. Figure 6 is a front view of the plate 48. As shown in Figures 4 to 6, the pin support portion 45 is composed of the plate 48, a pair of legs 49, 50, and a connection portion 51. The pin support portion 45 is, for example, integrally molded.

The plate 48 is a plate-like member having a front surface (surface facing right) and a back surface (surface facing left). The plate 48 is formed with a pair of rod insertion holes 52a, 52b and multiple pin support holes 53a, 53b, 53c, 53d, 53e, 53f, 53g, 53h, 53i (hereinafter, these may be collectively referred to as "pin support holes 53"). The rod insertion holes 52a, 52b and the pin support holes 53 penetrate the plate 48 in the thickness direction (between the front surface and the back surface).

The pair of rod insertion holes 52a, 52b are arranged at positions that are point symmetrical with respect to the center of the plate 48 (the position of the pin support hole 53e). The pair of rod insertion holes 52a, 52b are also arranged with a vertical offset. More specifically, when looking at the injection molding machine 10 from the front side, the rod insertion hole 52a on the near side is located lower than the rod insertion hole 52b on the far side. The pair of guide rods 46 are inserted into the rod insertion holes 52a, 52b.

The multiple pin support holes 53 are formed at multiple positions spaced apart in the up-down and front-rear directions of the plate 48. The pin support hole 53e is formed at the center of the plate 48 (e.g., at the center of gravity). The multiple pin support holes 53 support multiple ejector pins 47. More specifically, the ejector pins 47 supported by the pin support holes 53 are fastened (fixed) from the back side of the plate 48 by bolts. The positions and number of the pin support holes 53 (in other words, the ejector pins 47) are not limited to the above example. However, the ejector pins 47 are provided at least in the center of the plate 48.

The plate 48 also has notches 54a, 54b at the front upper corner and rear lower corner. As shown in FIG. 3, the movable die plate 25 has a recess 25a on the surface opposite to the surface supporting the movable die 24 (i.e., the left surface). When the pin support 45 advances together with the ball screw shaft 44, the plate 48 enters the recess 25a. Therefore, the recess 25a can be reduced in size only in the portion corresponding to the notches 54a, 54b.

The pair of legs 49, 50 protrude leftward (i.e., in the opposite direction to the ejector pin 47) from the rear surface of the plate 48. The pair of legs 49, 50 are arranged at positions that are point-symmetrical with respect to the center of the plate 48. Furthermore, the pair of legs 49, 50 are arranged at positions that are offset in the vertical direction. More specifically, when viewed from the front side of the injection molding machine 10, the front leg 49 is located lower than the rear leg 50.

That is, the pair of rod insertion holes 52a, 52b (in other words, the pair of guide rods 46) and the pair of legs 49, 50 are arranged offset in the same direction with respect to the center of the plate 48. The pair of legs 49, 50 are provided on the inside of the pair of rod insertion holes 52a, 52b (at a position close to the center of the plate 48). In contrast, the pair of notches 54a, 54b are provided in the corner opposite the pair of legs 49, 50.

The connection part 51 connects the protruding ends of the pair of legs 49, 50. That is, the connection part 51 passes through a position facing the center of the plate 48 at a position spaced apart from the plate 48 in the left-right direction. The connection part 51 supports the tip of the ball screw shaft 44 at a position facing the center of the plate 48. More specifically, the tip of the ball screw shaft 44 is inserted into a through hole provided in the connection part 51 and is fastened with a nut 55 or the like.

The tip of the ball screw shaft 44 supported by the connection portion 51 and the bolt that fixes the ejector pin 47 inserted into the pin support hole 53e face each other. In addition, the tip of the ball screw shaft 44 supported by the connection portion 51 and the bolt that fixes the ejector pin 47 inserted into the pin support hole 53e are spaced apart in the left-right direction (in other words, the extension direction of the ball screw shaft 44 and the ejector pin 47).

According to the above embodiment, the pin support portion 45 is advanced and retreated by a single ball screw shaft 44, which provides the following advantages compared to an ejector device having multiple ball screws.

First, there is no need to take time to adjust the parallelism of the ball screw shaft 44. Also, it is possible to prevent moment loads from being applied to the ball screw shaft 44 due to assembly errors in the ejector device 40. Also, the contact area of the belt 43c with the gears 43a and 43b is increased, preventing teeth skipping of the belt 43c. Also, by reducing the number of ball screws, the workload of the ejector motor 41 is reduced. As a result, the moment of inertia is reduced, and the acceleration and deceleration performance of the ejector pin 47 is improved. Furthermore, the number of parts in the ejector device 40 is reduced, which contributes to shorter delivery times and reduced manufacturing costs.

The ejector device 40 according to this embodiment employs a so-called "center pull back method" in which the ejector pins 47 attached to multiple positions including the center of the plate 48 are protruded from the movable mold 24 by the forward rotation of the ejector motor 41, and retracted into the movable mold 24 by the reverse rotation of the ejector motor 41. In addition, when there is only one ball screw shaft 44, it is necessary to place the ball screw shaft 44 at a position facing the center of the plate 48 in order to move the plate 48 back and forth in parallel.

Therefore, according to the above embodiment, by arranging a pair of legs 49, 50 at a position off-center of the plate 48, it is possible to prevent interference between the tip of the ball screw shaft 44 supported by the connection portion 51 and the bolt that secures the ejector pin 47 inserted into the pin support hole 53e.

In addition, according to the above embodiment, the pair of legs 49, 50 are arranged offset in the vertical direction, making it easier to access the space between the plate 48 and the connection part 51 from diagonally above. This improves the ease of maintenance, such as attaching and removing the bolts that secure the ejector pin 47 and cleaning the lubricating oil supply port 44a. In particular, since maintenance is generally performed from the front side of the injection molding machine 10, by arranging the front leg 49 lower than the rear leg 50, the ease of maintenance is further improved.

However, the vertical position of the pair of legs 49, 50 varies depending on which side of the injection molding machine 10 maintenance is performed from and the relative position of the part to be maintained and the operator's line of sight, so it is not limited to the above example.

In addition, according to the above embodiment, the pair of guide rods 46 are arranged offset in the same direction as the pair of legs 49, 50 with respect to the center of the plate 48, and the notches 54a, 54b are formed in the corners of the plate 48 opposite the pair of legs 49, 50, so that the area of the recess 25a formed in the movable die plate 25 can be reduced. As a result, the rigidity of the movable die plate 25 can be prevented from decreasing.

Furthermore, according to the above embodiment, the lubricant supply port 44a is formed at the tip of the ball screw shaft 44 exposed from the connection portion 51, so the overall length of the ball screw shaft 44 can be shortened compared to when the lubricant supply port is formed on the outer circumferential surface of the ball screw shaft 44. As a result, it is possible to prevent the injection molding machine 10 from becoming large.

The above-described embodiments are illustrative examples of the present invention, and are not intended to limit the scope of the present invention to these embodiments. Those skilled in the art can implement the present invention in various other forms without departing from the spirit of the present invention.

10... injection molding machine, 11... operation panel, 20... mold clamping device, 21... mold, 22... fixed side mold, 23... fixed die plate, 24... movable side mold, 25... movable die plate, 25a... recess, 26... toggle link mechanism, 27... tie bar, 30... injection device, 31... heating cylinder, 32... screw, 33... hopper, 34... hopper block, 35... screw passage, 36... nozzle, 40... ejector device, 41... ejector motor, 42...rotating nut, 43...driving force transmission mechanism, 43a, 43b...gear, 43c...belt, 44...ball screw shaft, 44a...lubricant supply port, 44b...axial internal passage, 44c...radial internal passage, 45...pin support, 46...guide rod, 47...ejector pin, 48...plate, 49, 50...leg, 50...leg, 51...connection, 52a, 52b...rod insertion hole, 53...pin support hole, 54a, 54b...notch, 55...nut

Claims (5)

a mold clamping device that opens/closes and clamps the fixed mold and the movable mold by moving a movable die plate that supports a movable mold toward and away from a fixed die plate that supports a fixed mold;
an injection device that injects a measured amount of molding material into cavities of the fixed mold and the movable mold that are clamped;
an ejector device for ejecting a molded product from the movable mold when the mold is opened,
The ejector device is
An ejector motor;
a rotating nut that is rotated by the driving force of the ejector motor;
A ball screw shaft that is screwed into the rotating nut and moves forward and backward as the rotating nut rotates;
a pin support portion fixed to a tip end of the ball screw shaft;
a plurality of ejector pins supported by the pin support portion and protruding from and retracting in relation to an inner surface of the movable die in accordance with the advancement and retreat of the ball screw shaft;
The pin support portion is
a plate supporting the plurality of ejector pins at a plurality of locations including a center of a surface thereof;
A pair of legs protruding from the rear surface of the plate at positions point-symmetrical with respect to the center of the plate and offset in the vertical direction;
a connection portion that connects the protruding ends of the pair of legs together at a position spaced from the plate in the extension direction of the ball screw shaft , and that supports the ball screw shaft at a position corresponding to the center of the plate. The molding machine according to claim 1, characterized in that the pair of legs are offset downward from the front leg relative to the rear leg when the molding machine is viewed from the front side. the ejector device includes a pair of guide rods that are inserted through the plate and guide the pin support portion as it advances and retreats;
3. The molding machine according to claim 1, wherein the pair of guide rods are arranged offset from the center of the plate in the same direction as the pair of legs. the movable die plate has a recess into which the advanced plate enters, on a surface opposite to a surface supporting the movable die,
4. The molding machine according to claim 3, wherein the plate has cutouts formed at corners that are point-symmetrical with respect to a center of the plate and are opposite the pair of legs. The ball screw shaft is
a lubricant supply port formed at a tip spaced from the back surface of the plate;
5. The molding machine according to claim 1, further comprising an internal passage for supplying the lubricating oil supplied through the lubricating oil supply port to the rotating nut.

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