Clamping device and molding machine

Abstract

The present invention provides a mold clamping device that can equalize the contact pressure between the clamped fixed mold and the movable mold while suppressing an increase in the weight of the movable die plate. [Solution] The clamping device comprises a fixed die plate that supports the fixed side mold, a movable die plate that supports the movable side mold on the front facing the fixed die plate and is movable to move toward and toward the fixed die plate, and a toggle link mechanism that moves the movable die plate forward and backward. The movable die plate has a pair of mounting parts to which the toggle link mechanism is attached, an internal space formed between the pair of mounting parts, and an opening that exposes the internal space to the rear, at vertically spaced positions on the back. The projected area of ​​the opening as viewed from the direction of movement of the movable die plate is smaller than the projected area of ​​the internal space.

Description

Technical Field

[0005] ,

[0001] The present invention relates to a clamping device capable of proper clamping and a molding machine equipped with the same.

Background Art

[0002] Conventionally, there has been known a clamping device that opens and closes and clamps a fixed-side mold and a movable-side mold by a fixed die plate that supports the fixed-side mold and a movable die plate that supports the movable-side mold and is movable back and forth in a direction of approaching and separating from the fixed die plate (see, for example, Patent Documents 1 to 4).

[0003] In such a clamping device, it is common to move the movable die plate back and forth by expanding and contracting a toggle link mechanism that is attached to the opposite side of the movable die plate of the movable die plate in the vertical direction and spaced apart.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when the mold is clamped, the movable die plate is subjected to a load from the toggle link mechanism that causes a concave shape in the center of the surface supporting the movable mold. As a result, the contact pressure between the center of the fixed and movable molds decreases, which can lead to gas buildup and burr formation. On the other hand, increasing the rigidity of the movable die plate to suppress deformation creates a new problem: increased weight.

[0006] The present invention has been made in view of the above circumstances, and its purpose is to provide a mold clamping device that can equalize the contact pressure between the clamped fixed mold and the movable mold while suppressing an increase in the weight of the movable die plate. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides a mold clamping device for opening, closing and clamping a fixed mold and a movable mold, comprising: a fixed die plate that supports the fixed mold; a movable die plate that supports the movable mold on its front surface facing the fixed die plate and is movable to move toward and toward the fixed die plate; and a toggle link mechanism for moving the movable die plate forward and backward, wherein the movable die plate has a pair of mounting parts to which the toggle link mechanism is attached at vertically spaced positions on its back surface, an internal space formed between the pair of mounting parts, and an opening that exposes the internal space to the back surface, and the projected area of ​​the opening as viewed from the direction of movement of the movable die plate is smaller than the projected area of ​​the internal space. [Effects of the Invention]

[0008] According to the present invention, it is possible to equalize the contact pressure between the clamped fixed mold and the movable mold while suppressing an increase in the weight of the movable die plate. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side view of the injection molding machine according to this embodiment. [Figure 2]This is an enlarged view of the main parts of the movable die plate, toggle link mechanism, and ejector device. [Figure 3] This is a perspective view of the movable die plate from the front (A) and the back (B). [Figure 4] This is a rear view of the movable die plate. [Figure 5] This is a cross-sectional perspective view at point AA in Figure 4. [Figure 6] Figure 4 is a cross-sectional perspective view of BB. [Figure 7] This is a cross-sectional view perpendicular to AA and BB in Figure 4. [Figure 8] This figure shows the shape of a movable die plate in a conventional configuration. [Figure 9] This figure shows the surface pressure distribution between the fixed mold and the movable mold when clamping is performed with the movable die plates of the conventional form (A) and this embodiment (B). [Modes for carrying out the invention]

[0010] 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 molding machine that injects molten resin (molding material) measured into a mold to form a molded product. However, the specific example of a molding machine is not limited to the injection molding machine 10, and may also be a die-casting machine that injects molten metal (molding material) into a mold to form a molded product.

[0011] [Configuration of injection molding machine 10] Figure 1 is a side view of the injection molding machine 10 according to this embodiment. As shown in Figure 1, the injection molding machine 10 mainly comprises a mold clamping device 20, an injection device 30, and an ejector device 40 (see Figure 2).

[0012] The mold clamping device 20 opens and closes the mold 21 and clamps it. Specifically, the mold clamping device 20 mainly comprises a fixed die plate 23 that supports the fixed side mold 22 and a movable die plate 25 that supports the movable side mold 24. The fixed side mold 22 and the movable side mold 24 are supported so as to face each other in the left-right direction (horizontal direction) of the injection molding machine 10.

[0013] The movable die plate 25 moves forward and backward in the left - right direction along the tie bar 27 when the driving force of a mold - opening / closing motor (not shown) is transmitted through the toggle link mechanism 26. When the movable die plate 25 moves backward to the left, the fixed - side mold 22 and the movable - side mold 24 are separated. On the other hand, when the movable die plate 25 moves forward to the right, the fixed - side mold 22 and the movable - side mold 24 come into contact with each other, and a cavity (internal space) is formed inside the mold 21. And when a pressure in the direction of moving the movable die plate 25 forward to the right is further applied, the fixed - side mold 22 and the movable - side mold 24 are clamped.

[0014] The injection device 30 plasticizes, measures, and injects the molding material. The injection device 30 according to the present embodiment is arranged to face the mold - clamping device 20 in the horizontal direction (to the right of the mold - clamping device 20). The injection device 30 mainly includes a heating cylinder 31, a screw 32, a hopper 33, and a hopper block 34.

[0015] The heating cylinder 31 is a cylindrical member extending in the left - right direction of the injection molding machine 10. The heating cylinder 31 mainly includes a resin passage 35 and a nozzle 36. Further, a band heater 39 for heating the heating cylinder 31 is attached to the outer peripheral surface of the heating cylinder 31. The band heater 39 is a so - called "thermocouple" that generates heat by receiving power supply from a control device, for example.

[0016] The resin passage 35 is a cylindrical space extending in the axial direction (longitudinal direction) inside the heating cylinder 31. The resin passage 35 communicates with the outside of the heating cylinder 31 (the cavity of the mold 21) through a nozzle 36 provided at the tip (front end) of the heating cylinder 31. In other words, the resin passage 35 is a space extending along the axial direction from the nozzle 36.

[0017] The screw 32 is a cylindrical component. A spiral groove (hereinafter referred to as "spiral groove") is formed on the outer surface of the screw 32, extending along the longitudinal direction of the screw 32. The screw 32 is housed in the internal space of the heating cylinder 31 in a state that allows for movement (hereinafter referred to as "advancing and retracting") and rotation in the left-right direction of the injection molding machine 10. Furthermore, the screw 32 inside the heating cylinder 31 is configured to be replaceable. In other words, screws 32 with different specifications (e.g., material, spiral groove shape, spiral groove volume) can be inserted into the heating cylinder 31.

[0018] The screw 32 moves forward and backward when driven by the injection motor (not shown), and rotates when driven by the metering motor (not shown). More specifically, when the injection motor is rotated forward, the screw 32 moves (advance) toward the tip of the heating cylinder 31 (i.e., the nozzle 36). Conversely, when the injection motor is rotated backward, the screw 32 moves (reverse) toward the base end of the heating cylinder 31 (i.e., the side opposite the nozzle 36).

[0019] Hereinafter, within the range that the tip of the screw 32 can reach within the heating cylinder 31, the position closest to the nozzle 36 will be referred to as the "forward limit," and the position furthest from the nozzle 36 will be referred to as the "reverse limit." Furthermore, the terms "forward rotation" and "reverse rotation" for the injection motor do not specify an absolute direction of rotation, but merely specify a relative relationship (i.e., forward rotation and reverse rotation are rotations in opposite directions).

[0020] The hopper 33 is a funnel-shaped component that stores granular resin, which is the raw material. The hopper block 34 is a component that supports the heating cylinder 31 and the hopper 33. The hopper 33 communicates with the resin passage 35 through the hopper block 34, on the base side of the tip of the heating cylinder 31. The granular resin stored in the hopper 33 is supplied to the resin passage 35 of the heating cylinder 31 through an opening provided at the lower end. The granular resin used in this injection molding machine 10 is, for example, a so-called "pellet" that is molded into a cylindrical shape.

[0021] The injection device 30 rotates the screw 32 backward while rotating the injection motor in the reverse direction and the metering motor. As a result, the pellets supplied through the hopper 33 are plasticized and filled (metered) into the resin passage 35 in front of the screw 32. The injection device 30 also rotates the injection motor forward, causing the screw 32 to move forward. As a result, the molten resin filled into the resin passage 35 in front of the screw 32 is injected into the cavity of the mold 21 through the nozzle 36.

[0022] The hopper 33 is supplied with different types of resin (for example, different degrees of plasticity) depending on the molded product. The particle size of the pellets supplied to the hopper 33 varies depending on the raw material supply device (not shown) that supplies the raw materials to the hopper 33. Furthermore, in addition to pellets, recycled resin may be supplied to the hopper 33. Recycled resin refers to unwanted parts (runners) separated from the molded product, resin discharged (purged) from the heating cylinder 31, etc.

[0023] [Description of toggle link mechanism 26] Figure 2 is an enlarged view of the main parts of the movable die plate 25, the toggle link mechanism 26, and the ejector device 50. Hereinafter, the side of the movable die plate 25 that supports the movable mold 24 will be referred to as the "front side," and the side opposite the front will be referred to as the "back side." The direction perpendicular to the thickness direction and vertical direction of the movable die plate 25 (the direction perpendicular to the plane of the paper in Figure 2) will be referred to as the "width direction" of the movable die plate 25. That is, in Figure 1, the front of the movable die plate 25 faces to the right, the back of the movable die plate 25 faces to the left, and the width direction corresponds to the front-to-back direction (the direction perpendicular to the plane of the paper in Figure 1). The thickness direction of the movable die plate 25 corresponds to the "advance-to-return direction" of the movable die plate 25.

[0024] As shown in Figure 2, the toggle link mechanism 26 comprises a pair of toggle links 41 and 42. Toggle link 41 consists of multiple link arms 41b and 41c rotatably connected by a support shaft 41a extending in the width direction. Similarly, toggle link 42 consists of multiple link arms 42b and 42c rotatably connected by a support shaft 42a extending in the width direction. Figure 2 shows only the two link arms on the movable die plate 25 side.

[0025] One end of each toggle link 41, 42 is rotatably supported on the tailstock 43 (see Figure 1) by a support shaft (not shown) extending in the width direction. The other end of each toggle link 41, 42 is rotatably supported on the mounting portions 60a, 60b of the movable die plate 25 by support shafts 41d, 42d extending in the width direction. In other words, the toggle links 41, 42 are attached to mounting portions 60a, 60b that are spaced apart in the vertical direction.

[0026] When the mold opening / closing motor rotates forward, the toggle links 41 and 42 extend, as shown in Figure 2(A), causing the movable die plate 25 to move forward. This closes and clamps the mold 21. On the other hand, when the mold opening / closing motor rotates backward, the toggle links 41 and 42 retract, as shown in Figure 2(B), causing the movable die plate 25 to move backward. This opens the mold 21. Note that the "forward rotation" and "reverse rotation" of the mold opening / closing motor, like the injection motor, merely specify a relative relationship.

[0027] Furthermore, as indicated by the arrows in Figure 2(A), when the mold 21 is clamped, a load is applied from the toggle link mechanism 26 to the movable die plate 25 that attempts to separate the mounting portions 60a and 60b in the vertical direction. In other words, when the mold 21 is clamped, the toggle link mechanism 26 applies a load that causes the center of the front surface of the movable die plate 25 to be recessed.

[0028] [Description of ejector device 50] The ejector device 50 is a device that separates the molded product from the opened mold 21. The ejector device 50 is attached to the rear side of the movable die plate 25. The ejector device 50 mainly comprises, for example, an ejector plate 51, ejector pins 52, lead screws 53a and 53b, drive nuts 54a and 54b, and an ejector motor 55. Although only one ejector pin 52 is shown in Figure 2, there may be multiple ejector pins 52.

[0029] The ejector device 50 separates the molded product from the inner surface of the movable mold 24 by extending and retracting the ejector pin 52 relative to the inner surface of the movable mold 24 (the surface defining the cavity). The ejector device 50 moves back and forth between the retracted limit shown in Figure 2(A) and the forward limit shown in Figure 2(B). The retracted limit is the position where the tip of the ejector pin 52 (the end that can contact the molded product) is retracted into the movable mold 24. The forward limit is the position where the tip of the ejector pin 52 protrudes from the inner surface of the movable mold 24, separating the molded product from the movable mold 24.

[0030] The ejector plate 51 supports the ejector pins 52 on the side facing the movable die plate 25. The ejector pins 52 protrude from the ejector plate 51 toward the movable die plate 25 and are inserted into pin holes 62a to 62d (see Figures 3 to 7) that penetrate the movable die plate 25. Furthermore, when the ejector device 50 is in its forward position, the ejector pins 52 protrude from the inner surface of the movable mold 24, separating the molded product from the movable mold 24.

[0031] Furthermore, the ejector plate 51 supports the feed screws 53a and 53b. The feed screws 53a and 53b protrude from the ejector plate 51 toward the movable die plate 25 and are screwed into the drive nuts 54a and 54b. The ejector plate 51 is configured to move back and forth together with the feed screws 53a and 53b.

[0032] The drive nuts 54a and 54b are rotatably supported via bearings (not shown) in relief holes 63a and 63b provided on the back of the movable die plate 25. The drive nuts 54a and 54b rotate when the driving force of the ejector motor 55 is transmitted to them. As a result, the feed screws 53a and 53b, which are screwed onto the drive nuts 54a and 54b, move forward and backward together with the ejector plate 51 and the ejector pin 52.

[0033] The ejector motor 55 generates a driving force that moves the ejector pins 52 forward and backward. When the ejector motor 55 rotates forward, the ejector plate 51, ejector pins 52, and lead screws 53a and 53b move forward together from the retraction limit to the forward limit. On the other hand, when the ejector motor 55 rotates backward, the ejector plate 51, ejector pins 52, and lead screws 53a and 53b move backward together from the forward limit to the retraction limit. Note that the "forward rotation" and "reverse rotation" of the ejector motor 55 merely specify a relative relationship, similar to the injection motor.

[0034] [Description of movable die plate 25] Figure 3 is a perspective view of the movable die plate 25 from the front (A) and rear (B) sides. Figure 4 is a rear view of the movable die plate 25. Figure 5 is a cross-sectional perspective view at AA in Figure 4. Figure 6 is a cross-sectional perspective view at BB in Figure 4. Figure 7 is a cross-sectional view perpendicular to AA and BB in Figure 4.

[0035] As shown in Figures 3 to 7, the movable die plate 25 has a flattened, roughly rectangular parallelepiped shape with shorter dimensions in the thickness direction compared to the vertical and width directions. The movable die plate 25 has a pair of mounting portions 60a and 60b. The movable die plate 25 also has a plurality of guide holes 61a, 61b, 61c, and 61d, a plurality of pin holes 62a, 62b, 62c, and 62d, a pair of relief holes 63a and 63b, a plurality of weight-reducing holes 64a, 64b, 64c, and 64d, an internal space 65, an opening 66, and communication holes 67a and 67b.

[0036] Mounting portions 60a and 60b are provided on the back surface of the movable die plate 25. Furthermore, mounting portions 60a and 60b are located at positions separated vertically (in other words, on opposite sides of the pin holes 62a-62d, relief holes 63a and 63b, internal space 65, opening 66, and communication holes 67a and 67b in the vertical direction). In addition, mounting portions 60a and 60b protrude rearward (towards the tailstock 43) from the back surface of the movable die plate 25. Mounting portions 60a and 60b rotatably support the other ends of the toggle links 41 and 42 via support shafts 41d and 42d.

[0037] Guide holes 61a to 61d are located at the four corners of the movable die plate 25, and each penetrates the movable die plate 25 in the thickness direction. Tie bars 27 are inserted into each of the guide holes 61a to 61d. As a result, the movable die plate 25 can move back and forth along the tie bars 27 inserted into the guide holes 61a to 61d.

[0038] When the movable die plate 25 is viewed from the thickness direction, the guide holes 61a to 61d are located at positions corresponding to the vertices of a rectangle (square). Hereinafter, as shown in Figure 4, the intersection of the line connecting the diagonally opposite guide holes 61a and 61c and the line connecting the diagonally opposite guide holes 61b and 61d will be denoted as the center C of the movable die plate 25.

[0039] The pin holes 62a to 62d are located inside the guide holes 61a to 61d (closer to the center C), and each penetrates the movable die plate 25 in the thickness direction. The pin holes 62a to 62d are also provided at multiple positions spaced apart in the vertical and width directions. An ejector pin 52 is inserted into each of the pin holes 62a to 62d.

[0040] In Figures 3 to 7, reference numbers are assigned only to some of the pin holes 62a to 62d, while the assignment of reference numbers to the other pin holes is omitted. Also, the ejector pins 52 do not need to be inserted into all of the pin holes 62a to 62d...; they may be inserted into only some of the pin holes 62a to 62d to match the shape of the molded product.

[0041] The relief holes 63a and 63b are located inside the guide holes 61a to 61d and outside the internal space 65 and the opening 66 (away from the center C), extending in the forward and backward direction from the back of the movable die plate 25 (in other words, they are recessed). The relief holes 63a and 63b open on the back side of the movable die plate 25, and the opposite side (the back side) is closed. That is, the relief holes 63a and 63b do not open on the front side of the movable die plate 25. The relief holes 63a and 63b rotatably support the drive nuts 54a and 54b. The relief holes 63a and 63b are also spaces that receive the forward feed screws 53a and 53b.

[0042] The weight-reducing holes 64a to 64d are recesses that are recessed in the forward and backward direction from the back surface of the movable die plate 25, located inside the guide holes 61a to 61d and outside the relief holes 63a and 63b, the internal space 65, and the opening 66. On the other hand, the weight-reducing holes 64a to 64d do not open to the front side of the movable die plate 25. The weight-reducing holes 64a to 64d are provided to reduce the weight of the movable die plate 25.

[0043] The internal space 65 is formed inside the movable die plate 25 (between the front and back surfaces). The internal space 65 is formed at a position that includes the center C of the movable die plate 25 when viewed from the thickness direction. More specifically, the internal space 65 is a figure that is rotationally symmetric with respect to the center C. Furthermore, the internal space 65 is located inside the guide holes 61a to 61d, the relief holes 63a and 63b, and the weight-reducing holes 64a to 64c.

[0044] The internal space 65 has a roughly rectangular shape when viewed from the thickness direction of the movable die plate 25. More specifically, the internal space 65 is a rectangle (e.g., a rhombus or square) with chamfered vertices. The internal space 65 is positioned with its vertices facing both sides in the vertical direction and both sides in the width direction. Furthermore, the internal space 65 extends in the thickness direction of the movable die plate 25 with a rectangular cross-section perpendicular to the thickness direction. In other words, the shape of the internal space 65 is a rectangular prism with chamfered vertices.

[0045] The internal space 65 is exposed to the front side of the movable die plate 25 through pin holes 62a to 62c, exposed to the back side of the movable die plate 25 through opening 66, and communicates with relief holes 63a and 63b through communication holes 67a and 67b.

[0046] The opening 66 is located on the back of the movable die plate 25. Furthermore, the opening 66 is positioned to face the internal space 65 when the movable die plate 25 is viewed from the thickness direction. The opening 66 is an elongated hole, longer in the vertical direction than in the width direction. More specifically, the opening 66 has a pair of sides facing each other in the width direction that extend parallel to each other in the vertical direction. Additionally, both ends of the opening 66 in the vertical direction are arc-shaped, following the chamfers at the vertices of the internal space 65.

[0047] Furthermore, the projected area of ​​the opening 66 viewed from the thickness direction of the movable die plate 25 is smaller than the projected area of ​​the internal space 65. More specifically, when the movable die plate 25 is viewed from the thickness direction, the vertical dimension of the opening 66 coincides with the length connecting the vertices at both ends of the internal space 65 in the vertical direction. On the other hand, the projected area of ​​the opening 66 viewed from the thickness direction of the movable die plate 25 is smaller than the projected area of ​​the internal space 65 in the width direction of the movable die plate 25.

[0048] In other words, the back surface of the movable die plate 25 closes off a roughly triangular region between the vertices at both ends of the internal space 65 in the left-right direction and the opening 66. In the plane of the movable die plate 25, the roughly triangular region (wall) that closes off both sides of the internal space 65 in the width direction functions as a reinforcing wall that improves the rigidity of the movable die plate 25.

[0049] Furthermore, when the movable die plate 25 is viewed from the thickness direction, some of the pin holes 62a to 62c are positioned to overlap with the opening 66. That is, some of the ejector pins 52 enter the internal space 65 through the opening 66 and protrude to the front side through the pin holes 62a to 62c. In other words, the internal space 65 and the opening 66 allow some of the ejector pins 52 to pass through.

[0050] The communication holes 67a and 67b connect the internal space 65 and the relief holes 63a and 63b within the movable die plate 25. More specifically, the communication holes 67a and 67b connect the relief holes 63a and 63b to the internal space 65 from behind the drive nuts 54a and 54b. Furthermore, the communication holes 67a and 67b extend in a direction perpendicular to the inner circumferential wall that defines the internal space 65.

[0051] [Effects of the Embodiment] Figure 8 shows the shape of a conventional movable die plate 25A. Of the components of the movable die plate 25A shown in Figure 8, the shapes of the internal space 65A and the opening 66A differ from the internal space 65 and opening 66 of the movable die plate 25, while the others are common to the movable die plate 25. In the movable die plate 25A shown in Figure 8, the components common to the movable die plate 25 are given the same reference numbers.

[0052] The internal space 65A and the opening 66A shown in Figure 8 exhibit a roughly cross-shaped outer form when the movable die plate 25A is viewed from the thickness direction. In other words, the internal space 65A and the opening 66A have the same projected shape when the movable die plate 25A is viewed from the thickness direction. Furthermore, the opening 66A in the conventional embodiment is larger in the width direction compared to the opening 66 in this embodiment (in other words, it lacks a portion that functions as a reinforcing wall).

[0053] Figure 9 shows the surface pressure distribution between the fixed mold 22 and the movable mold 24 when the molds are clamped using the movable die plates 25A and 25 in the conventional configuration (A) and this embodiment (B). In Figure 9, the change in surface pressure is represented by the shade of gray. More specifically, darker areas indicate higher surface pressure, and lighter areas indicate lower surface pressure. Also, in Figure 9, only the portion to the right of the straight line extending vertically through the center of the mold 21 is shown.

[0054] Figures 9(A) and 9(B) show that the surface pressure is lower closer to the center and higher closer to the outer edge (especially near the guide holes 61a to 61d). However, when using the movable die plate 25 according to this embodiment (Figure 9(B)), compared to using the movable die plate 25A according to the conventional embodiment (Figure 9(A)), it can be seen that the change in surface pressure in the center is smaller (the change in color is more gradual), and the difference between the minimum surface pressure in the center (lightest color) and the maximum surface pressure at the outer edge (darkest color) is smaller. In other words, the movable die plate 25 according to this embodiment has a smaller difference in surface pressure between the center and the outer edge compared to the movable die plate 25A according to the conventional embodiment (the distribution of surface pressure is more evenly distributed).

[0055] Furthermore, Figure 9(B) is generally darker in color compared to Figure 9(A) (in other words, the surface pressure has been increased). This is because the movable die plate 25 according to this embodiment has improved rigidity and less deformation during clamping compared to the movable die plate 25A of the conventional embodiment, so the clamping force can be transmitted to the mold 21 more efficiently.

[0056] In other words, according to this embodiment, by making the widthwise size of the opening 66 narrower than that of the opening 66A (i.e., by providing a reinforcing wall), the rigidity against the load received from the toggle link mechanism 26 is increased, making it less likely to deform in the direction indicated by the arrow in Figure 2(A). This allows the mold 21 to be properly clamped. On the other hand, as is clear from Figure 9(B), the size (projected area) of the internal space 65 does not have a significant effect on rigidity, so by maintaining the size of the internal space 65, it is possible to suppress an increase in the weight of the movable die plate 25.

[0057] Furthermore, according to the above embodiment, by making the widthwise length of the opening 66 shorter than the vertical length, the mold 21 can be properly clamped against the load received from the toggle link mechanism 26 attached to the mounting portions 60a and 60b which are spaced apart in the vertical direction.

[0058] Furthermore, as shown in Figure 2(A), when the feed screws 53a and 53b are advanced within the relief holes 63a and 63b, the air on the far side of the relief holes 63a and 63b is compressed, which can cause the temperature of the movable die plate 25 to rise. Therefore, by connecting the relief holes 63a and 63b with the internal space 65 via the communication holes 67a and 67b on the far side (front side) of the relief holes 63a and 63b from the drive nuts 54a and 54b, the air inside the relief holes 63a and 63b can be discharged through the internal space 65. This allows the feed screws 53a and 53b to advance smoothly and suppresses the temperature rise of the movable die plate 25.

[0059] Furthermore, according to the above embodiment, the number of pin holes can be reduced by using the opening 66 as a pin hole through which the ejector pin 52 passes. As a result, the rigidity of the movable die plate 25 can be further increased.

[0060] The embodiments described above are illustrative for explaining the present invention and are not intended to limit the scope of the invention to those embodiments only. Those skilled in the art can implement the present invention in various other forms without departing from the spirit of the invention. [Explanation of Symbols]

[0061] 10...Injection molding machine, 20...Clamping device, 21...Mold, 22...Fixed side mold, 23...Fixed die plate, 24...Movable side mold, 25...Movable die plate, 26...Toggle link mechanism, 27...Tie bar, 30...Injection device, 31...Heating cylinder, 32...Screw, 33...Hopper, 34...Hopper block, 35...Resin passage, 36...Nozzle, 39...Band heater, 40...Ejector device, 41,42...Toggle link, 41a,41d,42a,42d...Support shaft, 41b,41c,42b,42 c...Link arm, 43...Tailstock, 50...Ejector device, 51...Ejector plate, 52...Ejector pin, 53a, 53b...Lead screw, 54a, 54b...Drive nut, 55...Ejector motor, 60a, 60b...Mounting part, 61a, 61b, 61c, 61d...Guide hole, 62a, 62b, 62c, 62d...Pin hole, 63a, 63b...Relief hole, 64a, 64b, 64c, 64d...Weight reduction hole, 65, 65A...Internal space, 66, 66A...Opening, 67a, 67b...Communication hole

Claims

1. In a mold clamping device that opens, closes, and clamps a fixed mold and a movable mold, A fixed die plate supporting the fixed side mold, A movable die plate supports the movable side mold on its front surface facing the fixed die plate and is movable to move forward and backward in the direction toward and toward the fixed die plate, The movable die plate is further equipped with a toggle link mechanism for moving the die plate forward and backward. The aforementioned movable die plate is A pair of mounting parts on the back, spaced apart vertically, to which the toggle link mechanism is attached, The internal space formed between the pair of mounting parts, It has an opening that exposes the internal space to the rear surface, A clamping device characterized in that the projected area of ​​the opening, as viewed from the direction of advancement and retraction of the movable die plate, is smaller than the projected area of ​​the internal space.

2. In the clamping device according to claim 1, A clamping device characterized in that the projected area of ​​the opening as viewed from the aforementioned moving direction is smaller than the projected area of ​​the internal space in the width direction of the movable die plate, which is perpendicular to the vertical direction and the aforementioned moving direction.

3. In the clamping device according to claim 2, The clamping device is characterized in that the opening is longer in the vertical direction than in the width direction.

4. In the clamping device according to claim 3, The system includes an ejector device that separates the molded product from the movable side mold after it has been opened. The ejector device is The movable die plate has an ejector pin that penetrates it in the forward and backward direction, A drive nut rotatably supported on the aforementioned movable die plate, The system includes a feed screw that is screwed onto the drive nut and moves forward and backward together with the ejector pin as the drive nut rotates, The movable die plate includes: Extending from the rear in the forward and backward direction, it rotatably supports the drive nut and has a relief hole into which the forward feed screw enters, A clamping device characterized in that a communication hole is formed further back than the drive nut, which connects the relief hole to the internal space.

5. In the clamping device according to claim 4, The inner circumferential wall defining the internal space is a rectangle with vertices on both sides in the vertical direction and on both sides in the width direction when viewed from the direction of movement. The clamping device is characterized in that the communication hole extends in a direction perpendicular to the inner circumferential wall.

6. In the clamping device according to claim 4, The ejector device comprises a plurality of ejector pins, The clamping device is characterized in that the opening allows the ejector pin to pass through.

7. The clamping device according to claim 1, A molding machine characterized by comprising an injection device for injecting molding material into the cavities of the clamped fixed mold and the movable mold.

Images