Mold clamping device and injection molding machine

Abstract

To prevent the life deterioration and breakage of a screw shaft composing a ball screw provided in a mold clamping mechanism.SOLUTION: A mold clamping apparatus 2 has a mold clamping mechanism 20 comprising: a screw shaft 25; a cross head 23; and a cylindrical cover member 40 storing the screw shaft 25. The cover member 40 comprises: a backward cover member 50 arranged between a mold clamping housing 14 and the cross head 23; and a forward cover member 60 arranged between the cross head 23 and a movable platen 15, and the backward cover member 50 expands and contracts in accordance with a change in an opposing distance between the mold clamping housing 14 and the cross head 23 accompanied by the movement of the cross head 23.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mold clamping device and an injection molding machine. [Background technology]

[0002] Injection molding machines are known for manufacturing resin or metal parts of desired shapes. A typical injection molding machine is composed of a mold clamping device and an injection device. The mold clamping device holds a mold and opens and closes the mold. The injection device melts the resin or metal material and supplies the molten material to the mold clamping device.

[0003] The mold clamping device includes a mold clamping mechanism that opens and closes the mold, and the mold clamping mechanism includes a ball screw that converts rotational motion into linear motion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-35270 Summary of the Invention [Problem to be solved by the invention]

[0005] The ball screw provided in the mold clamping mechanism includes a screw shaft that is placed near the mold. From another perspective, the screw shaft is used in an environment where there is a risk of foreign matter such as mold release agent, burrs, and resin powder adhering to it.

[0006] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0007] In one embodiment, the mold clamping mechanism provided in the mold clamping device includes a screw shaft and a cylindrical cover member that houses the screw shaft. The cover members include a cover member disposed between a mold clamping housing and a crosshead, and a cover member disposed between the crosshead and a movable platen. The cover member disposed between the mold clamping housing and the crosshead expands and contracts in response to a change in the opposing distance between the mold clamping housing and the crosshead that occurs as the crosshead moves. [Effects of the Invention]

[0008] According to one embodiment, shortening of the life span and damage to the screw shaft constituting the ball screw provided in the mold clamping mechanism are prevented. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating an injection molding machine according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a part of the injection molding machine shown in FIG. 1. [Figure 3A] FIG. 2 is a partial cross-sectional view of the ball screw and its periphery shown in FIG. 1. [Figure 3B] FIG. 3 is a partial cross-sectional view of the ball screw and its periphery shown in FIG. 2. [Figure 4] FIG. 4 is an explanatory diagram showing a rear cover member. [Figure 5] FIG. 2 is a plan view showing the front surface of the mold clamping housing. [Figure 6] FIG. 2 is a plan view showing the back surface of the crosshead. [Figure 7] FIG. 3 is a cross-sectional view schematically showing a support member. [Figure 8] FIG. 4 is a partial perspective view showing a support member. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment will be described in detail below with reference to the drawings. In all drawings used to explain the embodiment, the same reference numerals are used to designate components and devices having the same or substantially the same functions, and repeated description will not be given.

[0011] <Injection molding machine> FIG. 1 is a schematic diagram showing an injection molding machine 1 according to this embodiment. The injection molding machine 1 is composed of a mold clamping unit 2 and an injection unit 3. Molds 11 and 12 are attached to the mold clamping unit 2. The mold clamping unit 2 opens and closes the attached molds 11 and 12. The injection unit 3 heats and melts a metal material (e.g., magnesium or a magnesium alloy). The injection unit 3 injects the molten metal material (molten metal) into the molds 11 and 12 attached to the mold clamping unit 2. More specifically, the injection unit 3 injects the molten metal into the cavities of the molds 11 and 12. In other words, the injection molding machine 1 according to this embodiment is a metal injection molding machine.

[0012] <Mold clamping device> The mold clamping unit 2 includes a fixed platen 13, a mold clamping housing 14, and a movable platen 15, which are provided on a bed 4. The fixed platen 13 and the mold clamping housing 14 are fixed to the bed 4. On the other hand, the movable platen 15 is slidable on the bed 4.

[0013] The fixed platen 13 and the mold clamping housing 14 are connected to each other by a plurality of tie bars 16 that pass through the movable platen 15. More specifically, the fixed platen 13 and the mold clamping housing 14 are connected by four tie bars 16. The movable platen 15 is slidable between the fixed platen 13 and the mold clamping housing 14 in the opposing directions.

[0014] A mold clamping mechanism 20 is provided between the mold clamping housing 14 and the movable platen 15. More specifically, a link-type mold clamping mechanism 20 is provided between the mold clamping housing 14 and the movable platen 15. From another perspective, a toggle mechanism is provided between the mold clamping housing 14 and the movable platen 15.

[0015] The mold clamping mechanism 20 moves the mold 11 attached to the movable platen 15 toward and away from the mold 12 attached to the fixed platen 13. When the mold 11 comes into contact with the mold 12, the molds 11 and 12 are closed. On the other hand, when the mold 11 moves away from the mold 12, the molds 11 and 12 are opened. While the mold clamping mechanism 20 is closing the molds 11 and 12, it can press the mold 11 against the mold 12 to prevent the molds 11 and 12 from opening.

[0016] <Injection device> The injection unit 3 is composed of a heating cylinder 30 and an injection nozzle 31, which are provided on the bed 4. The injection unit 3 is driven by a nozzle touch device 32 in a direction (forward) approaching the mold clamping unit 2, and also in a direction (rearward) away from the mold clamping unit 2. In other words, the injection unit 3 moves forward and backward (rearward) relative to the mold clamping unit 2. When the injection unit 3 moves forward to a predetermined position, the tip of the injection nozzle 31 comes into contact with the sprue bushing of the mold 12.

[0017] A hopper 33 is provided at the rear end side of the heating cylinder 30. The hopper 33 is a supply port for supplying metal material to the heating cylinder 30. A screw 34 is provided inside the heating cylinder 30. The screw 34 is driven within the heating cylinder 30. More specifically, the screw 34 is driven to rotate within the heating cylinder 30. The screw 34 is also driven linearly within the heating cylinder 30. The direction in which the screw 34 is driven linearly is the same as the direction in which the injection unit 3 moves relative to the mold clamping unit 2. In other words, the screw 34 is driven linearly within the heating cylinder 30 in a direction approaching the mold clamping unit 2 (forward) and a direction away from the mold clamping unit 2 (rearward).

[0018] The heating cylinder 30 melts the supplied metal material to produce molten metal. A heater for heating the heating cylinder 30 is provided around the heating cylinder 30. In this embodiment, multiple band heaters are wrapped around the outer periphery of the heating cylinder 30. The metal material supplied to the heating cylinder 30 is heated and melted by the heat emitted from the band heaters and by shear heat generated by the rotation of the screw 34.

[0019] <Method of manufacturing molded products> Next, we will explain an example of a procedure (process) for manufacturing a metal part using the injection molding machine 1 shown in Fig. 1. First, the molds 11 and 12 attached to the mold clamping device 2 are opened, and the injection device 3 is moved backward.

[0020] Thereafter, a metal material is charged into the hopper 33 of the injection device 3. For example, magnesium powder is charged into the hopper 33. Alternatively, the metal material may be charged into the hopper 33 in advance before the injection device 3 is moved backward.

[0021] The metal material fed into the hopper 33 passes through the hopper 33 and falls into the heating cylinder 30. The metal material supplied to the heating cylinder 30 is heated and melted. The molten metal material (molten metal) is sent to the tip side of the heating cylinder 30 by the rotation of the screw 34. From another perspective, the molten metal is filled between the screw 34 and the injection nozzle 31.

[0022] Thereafter, the injection device 3 is moved forward so that the tip of the injection nozzle 31 comes into contact with the sprue bushing of the mold 12 (the molds 11 and 12 are closed beforehand). Next, the screw 34 is moved forward within the heating cylinder 30. At this time, the screw 34 is not rotated. Then, molten metal is poured (injected) from the tip of the injection nozzle 31 into the cavities of the molds 11 and 12.

[0023] The screw 34 continues to apply pressure (holding pressure) to the molten metal even after it has been injected into the cavity. The holding pressure is equal to or less than the pressure (injection pressure / primary pressure) used to pour (inject) the molten metal into the cavity. The molds 11 and 12 are cooled while maintaining the holding pressure applied to the molten metal in the cavity.

[0024] While the molds 11 and 12 are cooling, the screw 34 is rotated again to prepare for the next injection. Specifically, the screw 34 is rotated to send molten metal to the tip side of the heating cylinder 30. In other words, the molten metal to be injected next is filled between the screw 34 and the injection nozzle 31. As a result, the screw 34 is moved backward by a reaction force. This process of moving the screw 34 backward while sending the molten metal forward is called "metering."

[0025] After the molds 11 and 12 have been cooled to a temperature below the solidification temperature of the molten metal in the cavity, the molds 11 and 12 are opened and the molded product is removed.

[0026] By repeating the above process, metal parts (molded products) of the same shape are continuously manufactured. In other words, metal parts (molded products) of the desired shape are mass-produced. Note that the above process may include additional steps such as degreasing and sintering the molded products removed from the molds 11 and 12.

[0027] <Mold clamping mechanism> The mold clamping mechanism 20 provided in the mold clamping device 2 is composed of links, a crosshead, a ball screw, etc. More specifically, the mold clamping mechanism 20 includes upper links 21a, 21b, and 21c and lower links 22a, 22b, and 22c. The mold clamping mechanism 20 also includes a crosshead 23 disposed between the upper links 21a, 21b, and 21c and the lower links 22a, 22b, and 22c. The mold clamping mechanism 20 also includes a ball screw 24 including a rotatably held screw shaft 25 and a nut member 26 threadedly coupled to the screw shaft 25.

[0028] Note that another set of similar links and ball screws is provided behind (on the counter-operation side) the links and ball screws shown in Fig. 1. In other words, one set of links and ball screws is provided on each of the operation side and counter-operation side of the mold clamping unit 2. However, the links and ball screws on the operation side and the links and ball screws on the counter-operation side have the same structure. Therefore, by clarifying the structure of the links and ball screws on the operation side shown in Fig. 1, the structure of the links and ball screws on the counter-operation side, which are not shown in Fig. 1, will also be clarified.

[0029] <link> One end (base end) of the upper link 21a and the lower link 22a is rotatably connected to the crosshead 23 by a pin. One end (base end) of the upper link 21b and the lower link 22b is rotatably connected to the mold clamping housing 14 by a pin. One end (base end) of the upper link 21c and the lower link 22c is rotatably connected to the movable platen 15 by a pin. Furthermore, one end (tip end) of the upper link 21b and the lower link 22b is rotatably connected to one end (tip end) of the upper link 21c and the lower link 22c by a pin. Furthermore, one end (tip end) of the upper link 21a and the lower link 22a is rotatably connected to the center or approximately the center in the longitudinal direction of the upper link 21b and the lower link 22b.

[0030] The links (upper links 21a, 21b, 21c and lower links 22a, 22b, 22c) expand and contract as the crosshead 23 moves. More specifically, when the crosshead 23 moves in a direction approaching the mold clamping housing 14 (when the crosshead 23 moves back), the links contract (bend) as shown in Fig. 1. On the other hand, when the crosshead 23 moves in a direction away from the mold clamping housing 14 (when the crosshead 23 moves forward), the links expand (tension) as shown in Fig. 2.

[0031] Furthermore, when the links are contracted, the movable platen 15, to which the base ends of the upper link 21c and the lower link 22c are connected, moves in a direction approaching the mold clamping housing 14. As a result, the mold 11 attached to the movable platen 15 moves away from the mold 12, and the molds 11 and 12 are opened. On the other hand, when the links are extended, the movable platen 15, to which the base ends of the upper link 21c and the lower link 22c are connected, moves in a direction away from the mold clamping housing 14. As a result, the mold 11 attached to the movable platen 15 is pressed against the mold 12, and the molds 11 and 12 are closed. In other words, the opening and closing of the molds 11 and 12 and the mold clamping are achieved by the extension and contraction of the links.

[0032] <Ball screw> Fig. 3A is a partial cross-sectional view of the ball screw 24 and its vicinity shown in Fig. 1. Fig. 3B is a partial cross-sectional view of the ball screw 24 and its vicinity shown in Fig. 2. One end of a screw shaft 25 of the ball screw 24 is rotatably held by a bearing provided in the mold clamping housing 14. Meanwhile, the other end of the screw shaft 25 is inserted into the crosshead 23.

[0033] The nut member 26 of the ball screw 24 is partially embedded in the crosshead 23 and is integrated with the crosshead 23. The nut member 26 is also threadedly coupled to the screw shaft 25. From another perspective, the screw shaft 25 passes through the nut member 26 embedded in the crosshead 23.

[0034] A plurality of balls (rolling elements) 27 are disposed between the screw shaft 25 and the nut member 26, and these balls 27 circulate between the screw shaft 25 and the nut member 26 endlessly.

[0035] The screw shaft 25 is rotationally driven by a driving force input via a gear, a belt, etc. When the screw shaft 25 rotates, the nut member 26 moves on the screw shaft 25 in the longitudinal direction (axial direction) of the screw shaft 25. As a result, the crosshead 23 integrated with the nut member 26 moves in the longitudinal direction of the screw shaft 25. In other words, the rotational motion of the screw shaft 25 is converted into the linear motion of the crosshead 23.

[0036] In the following description, the rotation direction of the screw shaft 25 that moves the crosshead 23 forward is defined as the "forward direction," and the rotation direction of the screw shaft 25 that moves the crosshead 23 backward is defined as the "reverse direction." However, these definitions are merely for the convenience of explanation.

[0037] According to the above definition, when the screw shaft 25 shown in Fig. 3A is rotated in the forward direction, the crosshead 23 advances and moves away from the mold clamping housing 14. On the other hand, when the screw shaft 25 shown in Fig. 3B is rotated in the reverse direction, the crosshead 23 retreats and moves closer to the mold clamping housing 14.

[0038] From another perspective, when the screw shaft 25 rotates, the opposing distance D between the mold clamping housing 14 and the crosshead 23 changes. More specifically, when the screw shaft 25 rotates forward, the opposing distance D between the mold clamping housing 14 and the crosshead 23 increases. On the other hand, when the screw shaft 25 rotates reversely, the opposing distance D between the mold clamping housing 14 and the crosshead 23 decreases.

[0039] <Cover material> The mold clamping mechanism 20 is provided with a cylindrical cover member 40 that houses the screw shaft 25. The cover member 40 includes a rear cover member 50 that houses a portion of the screw shaft 25 in the longitudinal direction, and a front cover member 60 that houses another portion (remaining portion) of the screw shaft 25 in the longitudinal direction. From another perspective, the screw shaft 25 is covered by the rear cover member 50 and the front cover member 60. However, the ratio of the portion covered by the rear cover member 50 to the portion covered by the front cover member 60 changes as the crosshead 23 moves.

[0040] However, regardless of the position of the crosshead 23, the entire screw shaft 25 is always covered by the cover member 40, and the screw shaft 25 is never exposed to the outside of the cover member 40. More specifically, the part of the screw shaft 25 protruding rearward (toward the mold clamping housing) of the crosshead 23 is always covered by the rear cover member 50. In addition, the part of the screw shaft 25 protruding forward (toward the movable platen) of the crosshead 23 is always covered by the front cover member 60.

[0041] In the following description, a part of the screw shaft 25 that protrudes rearward from the crosshead 23 and is covered by the rear cover member 50 may be referred to as a "rear protruding portion," and another part of the screw shaft 25 that protrudes forward from the crosshead 23 and is covered by the front cover member 60 may be referred to as a "front protruding portion." As described above, the lengths of the rear protruding portion and the front protruding portion change as the crosshead 23 moves.

[0042] <Rear cover member> The rear cover member 50 is disposed between the mold clamping housing 14 and the crosshead 23. Fig. 4 is an explanatory diagram showing the rear cover member 50. The rear cover member 50 of this embodiment is a bellows tube made of resin. A flange 51 is provided at one end of the rear cover member 50, and a flange 52 is provided at the other end. In addition, a plurality of ridges (protrusions) 53a and valleys (recesses) 53b are provided alternately between the flanges 51 and 52.

[0043] The flange 51 is fixed to the mold clamping housing 14, and the flange 52 is fixed to the crosshead 23. More specifically, the flange 51 is fixed to the front surface 14f of the mold clamping housing 14 that faces the crosshead 23. The flange 52 is fixed to the back surface 23b of the crosshead 23 that faces the mold clamping housing 14. From another perspective, the one surface of the mold clamping housing 14 that faces the crosshead 23 is the front surface 14f of the mold clamping housing 14. Also, the one surface of the crosshead 23 that faces the mold clamping housing 14 is the back surface 23b of the crosshead 23 (FIGS. 3A and 3B).

[0044] Fig. 5 is a plan view showing details of the front surface 14f of the mold clamping housing 14 to which the flange 51 is fixed. Fig. 6 is a plan view showing details of the back surface 23b of the crosshead 23 to which the flange 52 is fixed. A plurality of through holes 53 are formed in the flanges 51, 52 along the circumferential direction. The flange 51 is fixed to the front surface 14f of the mold clamping housing 14 by bolts 54 inserted into each of the through holes 53. The flange 52 is also fixed to the back surface 23b of the crosshead 23 by bolts 54 inserted into each of the through holes 53.

[0045] 3A and 3B again, the rear cover member 50, which is a bellows tube with one end fixed to the mold clamping housing 14 and the other end fixed to the crosshead 23, expands and contracts in accordance with the movement of the crosshead 23. More specifically, the overall length of the rear cover member 50 expands and contracts in accordance with the change in the opposing distance D between the mold clamping housing 14 and the crosshead 23 that accompanies the movement of the crosshead 23.

[0046] For example, when the crosshead 23 advances due to forward rotation of the screw shaft 25 and the opposing distance D between the mold clamping housing 14 and the crosshead 23 increases, the rear cover member 50 is stretched (Fig. 3A → Fig. 3B). On the other hand, when the crosshead 23 retreats due to reverse rotation of the screw shaft 25 and the opposing distance D between the mold clamping housing 14 and the crosshead 23 decreases, the rear cover member 50 is compressed (Fig. 3B → Fig. 3A).

[0047] As shown in FIG. 4, the flange 51 is circular or approximately circular, while the flange 52 is non-circular. More specifically, the flange 52 is provided with two notches 55. As a result, when the flange 52 is fixed to the back surface 23b of the crosshead 23, a gap 56 is formed between the crosshead 23 and the rear cover member 50 (flange 52) (FIG. 6). In this embodiment, tubes 57 for supplying grease to the screw shaft 25 are inserted into the rear cover member 50 through the gaps 56 formed by the notches 55. In other words, the notches 55 form inlet ports (gaps 56) for inserting pipe members (tubes 57) for transporting lubricant to be supplied to the screw shaft 25 into the rear cover member 50.

[0048] The rear cover member 50 can be opened and closed. More specifically, the rear cover member 50 is provided with a fastener (zipper) 58. Therefore, the fastener 58 can be opened to check the state of the interior (screw shaft 25), etc. Furthermore, the rear cover member 50 can be removed or replaced without disassembling the mold clamping mechanism 20.

[0049] Although the fastener 58 in this embodiment is provided in a spiral shape on the body portion of the rear cover member 50, the fastener 58 may be provided in a straight line, for example. Also, the rear cover member 50 may be opened and closed using a fastener other than the fastener 58. Furthermore, in some embodiments, the rear cover member 50 is provided with a vent hole with a filter.

[0050] <Supporting member> Support members 70 are provided inside the rear cover member 50. Fig. 7 is a cross-sectional view schematically showing the support members 70 arranged inside the rear cover member 50. Fig. 8 is a partial perspective view showing one of the support members 70 arranged inside the rear cover member 50.

[0051] In this embodiment, a plurality of support members 70 are arranged inside the rear cover member 50. More specifically, three support members 70 are arranged inside the rear cover member 50. The support members 70 are aligned in a row in the longitudinal direction of the screw shaft 25. Each support member 70 includes a cylindrical portion 71 through which the screw shaft 25 is inserted, and a plate-shaped connecting portion 72 that extends radially outward from the cylindrical portion 71.

[0052] The connecting portion 72 is circular, and its edge is inserted into the inside of the ridge portion 53a of the rear cover member 50. As a result, forward and backward movement of the support member 70 is restricted. In addition, the edge of the connecting portion 72 that is inserted into the inside of the ridge portion 53a is fixed to the rear cover member 50. There are no particular limitations on the method for fixing the connecting portion 72. For example, the edge of the connecting portion 72 is fixed to the rear cover member 50 by crimping.

[0053] The support member 70 prevents bending and deformation of the rear cover member 50. In particular, when the rear cover member 50 is extended, the support member 70 effectively prevents bending of the rear cover member 50 due to its own weight. From another perspective, interference between the rear cover member 50 and the screw shaft 25 is effectively prevented.

[0054] The support member 70 is composed of two or more members that can be separated in the radial direction of the cylindrical portion 71. More specifically, the support member 70 is composed of a pair of half members 70a, 70b that can be separated in the radial direction of the cylindrical portion 71.

[0055] The halves 70a, 70b separate when the rear cover member 50 is opened. Therefore, although the support member 70 is fixed to the rear cover member 50, it does not hinder the opening and closing of the rear cover member 50. On the other hand, when the rear cover member 50 is closed, the halves 70a, 70b combine to form the support member 70. Note that "combined" here does not mean that the halves 70a, 70b become one unit. "Combined" here means that the end faces of the halves 70a, 70b are butted together or face each other with almost no gap between them.

[0056] The number and spacing of the support members 70 can be changed as appropriate depending on the length and thickness of the rear cover member 50. The support members 70 can also be omitted. For example, if the rear cover member 50 has enough strength to maintain its own shape, the support members 70 may be omitted.

[0057] <Front cover member> 3A and 3B again, the front cover member 60 is disposed between the crosshead 23 and the movable platen 15. The front cover member 60 is a cylindrical tube made of resin and has an inner diameter that allows the screw shaft 25 to pass in and out. One end (base end) of the front cover member 60 is open, and the other end (tip end) of the front cover member 60 is closed.

[0058] The base end of the front cover member 60 is fixed to the crosshead 23. On the other hand, the tip end of the front cover member 60 is not fixed to anything. In other words, the front cover member 60 is supported in a cantilevered manner.

[0059] The base end of the front cover member 60 is fixed by a bolt to the front surface 23f of the crosshead 23 (one surface of the crosshead 23 opposite to the back surface 23b). The front cover member 60 also communicates with a nut member 26 provided on the crosshead 23.

[0060] The centers of the screw shaft 25, the rear cover member 50, the nut member 26, and the front cover member 60 are on a common straight line. In other words, the screw shaft 25, the rear cover member 50, the nut member 26, and the front cover member 60 are coaxial.

[0061] The front cover member 60 fixed to the crosshead 23 moves back and forth together with the crosshead 23. As the crosshead 23 moves, a part of the screw shaft 25 protruding forward of the crosshead 23 is covered by the front cover member 60. From another perspective, the forward protruding part of the screw shaft 25 enters the front cover member 60.

[0062] The length of the forward protrusion of the screw shaft 25 changes (increases or decreases) as the crosshead 23 moves. Specifically, when the crosshead 23 moves backward, the length of the forward protrusion increases, and when the crosshead 23 moves forward, the length of the forward protrusion decreases. From another perspective, when the crosshead 23 moves backward, the penetration length of the screw shaft 25 into the front cover member 60 increases, and when the crosshead 23 moves forward, the penetration length of the screw shaft 25 into the front cover member 60 decreases.

[0063] The total length of the front cover member 60 is longer than the length of the forward protrusion when the crosshead 23 is moved to the most retracted position. Therefore, even if the crosshead 23 is moved back to the position where the length of the forward protrusion is at its longest, the front cover member 60 will not abut against the screw shaft 25.

[0064] On the other hand, the total length of the front cover member 60 is shorter than the distance between the crosshead 23 and the movable platen 15 when the crosshead 23 is at its most advanced position. Therefore, even if the crosshead 23 advances to the position where the length of the forward protrusion is shortest, the front cover member 60 will not abut against the movable platen 15.

[0065] As described above, in this embodiment, the screw shaft 25 constituting the mold clamping mechanism 20 is always covered by the cover member 40. Therefore, even if the mold clamping device 2 including the mold clamping mechanism 20 or the injection molding machine 1 including the mold clamping device 2 is used in a harsh environment, the life of the screw shaft 25 will not be shortened or the screw shaft 25 will not be damaged prematurely. For example, the life of the screw shaft 25 will not be shortened or the screw shaft 25 will not be damaged by mold release agent, burrs, resin powder, or other foreign matter adhering to the screw shaft 25.

[0066] In addition, because the cover members 40 (rear cover member 50 and front cover member 60) are detachable, maintenance of the screw shaft 25 and the nut member 26 is easy, and replacement of the cover members 40 is also easy. In particular, because the rear cover member 50 can be opened and closed, maintenance and inspection of the screw shaft 25 and the nut member 26 can be performed without removing the rear cover member 50.

[0067] The invention made by the inventor has been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from the spirit of the invention. For example, the shape, dimensions, material, etc. of the rear cover member 50 and the front cover member 60 can be modified as appropriate. Furthermore, the injection unit 3 can be replaced with an injection unit (resin injection unit) that injects molten resin into the molds 11, 12 attached to the mold clamping unit 2.

[0068] In the above embodiment, one set of links and ball screws are provided on each of the operating side and counter-operation side of the mold clamping unit 2. However, there are also embodiments in which one set of links and ball screws is provided at the center of the mold clamping unit. There are also embodiments in which the links constituting the mold clamping mechanism are not divided into the operating side and the counter-operation side. [Explanation of symbols]

[0069] 1 injection molding machine 2 Mold clamping device 3 Injection device 4 beds 11,12 Mold 13 Fixed plate 14 Mold clamping housing 14f front 15 Movable plate 16 Tie bar 20 Mold clamping mechanism 21a, 21b, 21c Upper link 22a, 22b, 22c Lower link 23 Crosshead 23b Back 23f front 25 screw shaft 26 Nut material 27 balls 30 Heating Cylinder 31 Injection nozzle 32 Nozzle touch device 33 Hopper 34 screw 40 Cover member 50 Rear cover member 51,52 flange 53 Through hole 53a Yamabe 53b Tanibe 54 volts 55 Notch 56 Gap 57 tubes 58 Zipper 60 Front cover member 70 Support member 70a, 70b Half-split member 71 Cylinder part 72 Connecting part D Opposite distance

Claims

1. A mold clamping device having a fixed platen and a movable platen to which a mold is attached, and a mold clamping mechanism that moves the movable platen relative to the fixed platen, The mold clamping mechanism includes: a screw shaft that is rotationally driven; A crosshead that moves with the rotation of the screw shaft; a first cover member disposed between the crosshead and a clamping housing that rotatably holds the screw shaft; and a second cover member disposed between the crosshead and the movable platen, the cylindrical cover member accommodating the screw shaft; a support member disposed inside the first cover member, the first cover member is a bellows tube having a plurality of alternating peaks and valleys, a first flange fixed to a front surface of the mold clamping housing is provided at one end of the first cover member; a second flange is provided at the other end of the first cover member and is fixed to a back surface of the crosshead that faces the front surface of the mold clamping housing; The support member includes a cylindrical portion through which the screw shaft is inserted, and a connecting portion that extends radially outward from the cylindrical portion and is inserted into the inside of the ridge portion of the first cover member, The first cover member expands and contracts in accordance with a change in the opposing distance between the clamping housing and the crosshead that accompanies movement of the crosshead.

2. The mold clamping device according to claim 1, The mold clamping device, wherein the support member is composed of two or more members that are separable from each other.

3. The mold clamping device according to claim 1 or 2, the second cover member is a cylindrical tube; One end of the second cover member is fixed to a front surface of the crosshead opposite to the back surface.

4. In the mold clamping device described in any one of claims 1 to 3, The mold clamping device, wherein the first cover member is openable and closable.

5. In the mold clamping device described in any one of claims 1 to 4, A mold clamping device, wherein the second flange of the first cover member is provided with a cutout portion that forms an inlet for pulling a pipe member that transports lubricant to be supplied to the screw shaft into the inside of the first cover member.

6. An injection molding machine comprising a mold clamping device to which a mold is attached, and an injection device that injects molten metal or molten resin into the mold, The mold clamping device is a fixed platen and a movable platen to which the mold is attached; a mold clamping mechanism that moves the movable platen relative to the fixed platen, The mold clamping mechanism includes: a screw shaft that is rotationally driven; A crosshead that moves with the rotation of the screw shaft; a first cover member disposed between the crosshead and a clamping housing that rotatably holds the screw shaft; and a second cover member disposed between the crosshead and the movable platen, the cylindrical cover member accommodating the screw shaft; a support member disposed inside the first cover member, the first cover member is a bellows tube having a plurality of alternating peaks and valleys, a first flange fixed to a front surface of the mold clamping housing is provided at one end of the first cover member; a second flange is provided at the other end of the first cover member and is fixed to a back surface of the crosshead that faces the front surface of the mold clamping housing; The support member includes a cylindrical portion through which the screw shaft is inserted, and a connecting portion that extends radially outward from the cylindrical portion and is inserted into the inside of the ridge portion of the first cover member, The injection molding machine, wherein the first cover member expands and contracts in accordance with a change in the opposing distance between the mold clamping housing and the crosshead caused by movement of the crosshead.

7. 7. The injection molding machine according to claim 6, the second cover member is a cylindrical tube; an injection molding machine, wherein one end of the second cover member is fixed to a front surface of the crosshead opposite to the back surface.

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