Mold clamping device, injection molding machine, and mold clamping method

Abstract

In order to suppress a decrease in mold clamping force, a mold clamping device (20) is provided with: a fixed mold (21) to which a fixed mold (26) is mounted; a moving die (22) to which the moving die (27) is mounted; a link housing (30) disposed on the opposite side of the movable mold (22) from the side on which the fixed mold (21) is disposed; a mold opening / closing mechanism (40) having a mold closing motor (60) for opening, closing and closing the movable mold (27) and the fixed mold (26); a tie bar (70) connected to the fixed mold (21) and the link housing (30); a mold thickness adjustment mechanism (80) having a tie bar nut (81) that is screwed to the threaded portion (71) of the tie bar (70) and is disposed on the link housing (30); and a control device (100) that controls the mold opening / closing mechanism (40) and the mold thickness adjustment mechanism (80). During mold clamping, the control device (100) causes the moving mold (27) to approach at a slight speed immediately before the moving mold (27) and the fixed mold (26) come into contact with each other, stops the mold clamping motor (60) for a predetermined period of time once the moving mold (27) and the fixed mold (26) come into contact with each other, and performs mold clamping by increasing the rotational speed of the mold clamping motor (60) after the predetermined period of time has elapsed.

Description

Technical Field

[0001] The invention relates to a mold clamping device, an injection molding machine and a mold clamping method. Background Art

[0002] An injection molding machine that performs molding by injecting molten resin in an injection cylinder into a mold has a mold clamping device that applies a mold clamping force to the mold, and molding is performed in the mold in a state where the mold clamping device applies a mold clamping force to a pair of molds. The mold clamping device has a fixed mold, a movable mold, a connecting rod housing, and a tie rod arranged between the fixed mold and the connecting rod housing, and the distance between the fixed mold and the movable mold can be changed by changing the distance between the movable mold and the connecting rod housing with the help of a connecting rod mechanism. Thus, the mold clamping device can apply a mold clamping force to the molds respectively arranged on the fixed mold and the movable mold.

[0003] In addition, the fixed mold and the tie rod are connected so as not to be relatively movable, and the tie rod nut disposed on the connecting rod housing is screwed with the tie rod in the connecting rod housing, and the distance between the fixed mold and the connecting rod housing can be changed by rotating the tie rod nut relative to the tie rod. Thus, the distance between the fixed mold and the movable mold can be changed, and the mold clamping force during molding can be adjusted.

[0004] Here, when the mold clamping force is generated by the mold clamping device by operating the link mechanism, a force in the direction of moving away from the fixed mold is applied to the link housing by the reaction when the mold clamping force is generated. When the force in the direction of moving away from the fixed mold acts on the link housing, the tie rod nut arranged on the link housing and screwed with the tie rod may rotate as the link housing moves. In this case, the distance between the fixed mold and the link housing changes, and when the mold clamping force is generated by operating the link mechanism, the desired mold clamping force cannot be generated, and molding defects may occur.

[0005] Therefore, conventional injection molding machines have a structure for detecting the rotation of the tie nut when the mold clamping force is generated. For example, in the injection molding machine described in Patent Document 1, the rotation state of the tie nut is directly or indirectly detected by an encoder arranged on a motor for rotating the tie nut, a rotation detector arranged near a gear for rotating the tie nut, etc. Thus, when the rotation of the tie nut is detected, it is determined that the mold clamping force has decreased, and a warning is issued, thereby preventing molding defects before they occur.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2014-213507 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, in order to prevent poor molding by issuing a warning when the rotation of the tie rod nut is detected, it is necessary to stop the molding by the injection molding machine after the warning, rotate the tie rod nut, and readjust the distance between the fixed mold and the connecting rod housing. In this case, since the molding process by the injection molding machine is interrupted, the efficiency of the injection molding machine in molding the molded product is reduced. Therefore, in order to prevent the interruption of the molding process, it is necessary to suppress the reduction of the clamping force, but in the conventional injection molding machine, it is difficult to suppress the reduction of the clamping force when the clamping force is repeatedly generated by the clamping device.

[0011] The present invention has been made in view of the above, and an object of the present invention is to provide a mold clamping device, an injection molding machine, and a mold clamping method capable of suppressing a decrease in the mold clamping force.

[0012] Means used to solve problems

[0013] In order to solve the above-mentioned problems and achieve the purpose, the mold clamping device of the present invention comprises: a fixed mold, on which the above-mentioned fixed mold of a pair of molds consisting of a fixed mold and a movable mold is installed; a movable mold, on which the above-mentioned movable mold is installed, and is arranged in an orientation in which the above-mentioned movable mold is opposite to the above-mentioned fixed mold installed on the above-mentioned fixed mold; a connecting rod housing, which is arranged on the side of the above-mentioned movable mold opposite to the side on which the above-mentioned fixed mold is arranged; a mold opening and closing mechanism, which has a toggle connecting rod connected to the above-mentioned connecting rod housing and the above-mentioned movable mold and capable of changing the distance between the above-mentioned connecting rod housing and the above-mentioned movable mold, and a mold clamping motor for actuating the above-mentioned toggle connecting rod, and the above-mentioned movable mold installed on the above-mentioned movable mold and the above-mentioned fixed mold are opened, closed and mold clamped by actuating the above-mentioned toggle connecting rod with the driving force generated by the above-mentioned mold clamping motor to move the above-mentioned movable mold relative to the above-mentioned connecting rod housing; a tie rod, one end of which is fixed to the above-mentioned fixed mold and the other end of which is connected to the above-mentioned connecting rod housing; a mold thickness adjustment mechanism, which has a connection with the mold formed on the upper The threaded portion on the other end side of the tie rod is screwed into a tie rod nut arranged on the connecting rod housing, and the connecting rod housing and the tie rod nut are relatively moved relative to the tie rod in the extension direction of the tie rod by rotating the tie rod nut, thereby adjusting the relative positions of the movable mold and the fixed mold installed on the movable mold connected to the connecting rod housing via the elbow connecting rod; and a control device for controlling the mold opening and closing mechanism and the mold thickness adjustment mechanism; when the mold is closed by the mold opening and closing mechanism from the open state of the mold to perform the above-mentioned mold closing, the control device rotates the mold closing motor at a slight speed before the movable mold is about to contact the fixed mold, so that the movable mold approaches the fixed mold at a slight speed, and once the movable mold contacts the fixed mold, the mold closing motor is stopped for a specified period of time, and the rotation speed of the mold closing motor is increased after the above-mentioned specified period of time to perform the above-mentioned mold closing.

[0014] In order to solve the above problems and achieve the purpose, the injection molding machine of the present invention comprises: the above-mentioned mold clamping device; and an injection device, which melts the resin material in an injection cylinder having a screw disposed inside, and injects the molten resin material into the above-mentioned mold from a nozzle.

[0015] Furthermore, in order to solve the above-mentioned problems and achieve the purpose, the mold clamping method of the present invention is a mold clamping method of a mold clamping device, wherein the mold clamping device comprises: a fixed mold, on which the above-mentioned fixed mold of a pair of molds consisting of a fixed mold and a movable mold is installed; a movable mold, on which the above-mentioned movable mold is installed, and is arranged in an orientation in which the above-mentioned movable mold is opposed to the above-mentioned fixed mold installed on the above-mentioned fixed mold; a connecting rod housing, which is arranged on the side of the above-mentioned movable mold opposite to the side on which the above-mentioned fixed mold is arranged; a mold opening and closing mechanism, which comprises a toggle connecting rod connected to the above-mentioned connecting rod housing and the above-mentioned movable mold and capable of changing the distance between the above-mentioned connecting rod housing and the above-mentioned movable mold, and a mold clamping motor for actuating the above-mentioned toggle connecting rod, and by actuating the above-mentioned toggle connecting rod with the driving force generated by the above-mentioned mold clamping motor, the above-mentioned movable mold installed on the above-mentioned movable mold and the above-mentioned fixed mold are moved relative to the above-mentioned connecting rod housing, thereby opening, closing and clamping the above-mentioned movable mold and the above-mentioned fixed mold; a tie rod, one end of which is fixed to the above-mentioned fixed mold and the other end of which is connected to the above-mentioned a connecting rod housing connection; and a mold thickness adjustment mechanism, comprising a connecting rod nut threadedly engaged with a threaded portion formed on the other end side of the above-mentioned tie rod and arranged on the above-mentioned connecting rod housing, by rotating the above-mentioned connecting rod nut so that the above-mentioned connecting rod housing and the above-mentioned connecting rod nut are relatively moved relative to the above-mentioned tie rod in the extension direction of the above-mentioned tie rod, thereby adjusting the relative positions of the above-mentioned movable mold and the above-mentioned fixed mold installed on the above-mentioned movable mold connected to the above-mentioned connecting rod housing via the above-mentioned elbow connecting rod; in the above-mentioned mold closing method, when the above-mentioned mold is closed by the above-mentioned mold opening and closing mechanism from the state where the above-mentioned mold is opened to perform the above-mentioned mold closing, the above-mentioned mold closing motor is rotated at a slight speed before the above-mentioned movable mold is about to contact the above-mentioned fixed mold, so that the above-mentioned movable mold approaches the above-mentioned fixed mold at a slight speed, and once the above-mentioned movable mold contacts the above-mentioned fixed mold, the above-mentioned mold closing motor is stopped for a specified period of time, and the rotation speed of the above-mentioned mold closing motor is increased after the above-mentioned specified period of time has passed to perform the above-mentioned mold closing.

[0016] The mold clamping device, injection molding machine, and mold clamping method according to the present invention have the effect of suppressing a decrease in the mold clamping force. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a side view of the injection molding machine related to the embodiment.

[0018] Figure 2 yes Figure 1 A side view of the mold clamping device is shown.

[0019] Figure 3 yes Figure 2 A-A view.

[0020] Figure 4 yes Figure 2 A detailed cross-sectional view of the connection between the tie rod and the connecting rod housing is shown.

[0021] Figure 5 This is a diagram for explaining the injection molding cycle performed by an injection molding machine.

[0022] Figure 6 This is an explanatory diagram regarding the operation of the mold clamping device in the mold clamping step.

[0023] Figure 7 is a detailed view of the tie rod and tie rod nut.

[0024] Figure 8 yes Figure 7 Detailed diagram of the Ba and Bb sections.

[0025] Fig. 9 This is a detailed view of the tie bar and the tie bar nut when the reaction force of the mold clamping force acts on the tie bar nut in a conventional injection molding machine.

[0026] Fig.10 yes Fig. 9 Detailed diagram of the Ca and Cb parts.

[0027] Fig.11 This is an explanatory diagram showing the relationship between the movement of the crosshead and the change in the mold clamping force when the mold is clamped by a conventional injection molding machine and the movement of the mold thickness adjustment motor.

[0028] Fig.12 It is an explanatory diagram showing the relationship between the movement of the crosshead and the change in the mold clamping force when the mold is clamped by the injection molding machine according to the embodiment and the movement of the mold thickness adjustment motor. DETAILED DESCRIPTION

[0029] Hereinafter, embodiments of the mold clamping device, injection molding machine, and mold clamping method disclosed herein will be described in detail based on the accompanying drawings. In addition, the invention is not limited by the embodiments. In addition, the components of the following embodiments include components that can be replaced and easily thought of by a person skilled in the art, or components that are substantially the same.

[0030] [Implementation Method]

[0031] Figure 11 is a side view of the injection molding machine 1 according to the embodiment. In the following description, the vertical direction of the injection molding machine 1 in the normal use state is set as the vertical direction Z of the injection molding machine 1, the upper side of the injection molding machine 1 in the normal use state is set as the upper side of the injection molding machine 1, and the lower side of the injection molding machine 1 in the normal use state is set as the lower side of the injection molding machine 1. In addition, in the following description, the longitudinal direction Y of the injection molding machine 1 is also set as the longitudinal direction Y in each part having the injection molding machine 1, and the direction orthogonal to both the vertical direction Z and the longitudinal direction Y of the injection molding machine 1 is set as the width direction X of the injection molding machine 1.

[0032] <Injection molding machine 1>

[0033] The injection molding machine 1 according to the present embodiment includes a fixed frame 5, an injection device 10 arranged on the frame 5, and a mold clamping device 20 arranged on the frame 5. The injection device 10 and the mold clamping device 20 are arranged side by side in the longitudinal direction Y on the frame 5, and the mold clamping device 20 is covered by a cover 6 on the frame 5.

[0034] <Injection Device 10>

[0035] The injection device 10 includes an injection cylinder 11, a screw 13, and a accumulator 14. The injection cylinder 11 is formed in a substantially cylindrical shape, and is arranged with the axial direction along the longitudinal direction Y. A nozzle 12 for injecting the resin material melted in the injection cylinder 11 is arranged at the end portion on one side where the mold clamping device 20 is located in the longitudinal direction Y. In detail, the injection cylinder 11 is provided with a heater such as a belt heater (not shown), and the temperature of the injection cylinder 11 can be increased by the heater. As a result, the injection cylinder 11 heats and melts the resin material inside the injection cylinder 11, and the resin material can be made into a molten resin as a plasticizer. The nozzle 12 is a portion that injects the molten resin material from the injection cylinder 11 to the outside of the injection cylinder 11.

[0036] The screw 13 is arranged inside the injection cylinder 11, and has a spiral shape whose axial direction is along the axial direction of the injection cylinder 11, that is, the screw 13 has a spiral groove on the outer peripheral surface. In this way, the screw 13 having the spiral groove can rotate around the axis in the injection cylinder 11. In addition, the screw 13 is arranged in the injection cylinder 11 in such a way that the central axis of the cylinder as the shape of the injection cylinder 11 and the rotation axis of the screw 13 are roughly consistent, and further, the screw 13 is arranged to be movable in the axial direction of the injection cylinder 11. The screw 13 rotatably arranged in the injection cylinder 11 can mix the molten resin by rotating inside the injection cylinder 11, and therefore, the injection cylinder 11 becomes a cylinder that can mix the molten resin inside.

[0037] A hopper 14 is arranged near the injection cylinder 11 on the opposite side of the side where the nozzle 12 is located in the longitudinal direction Y. The hopper 14 communicates with the injection cylinder 11 and can supply pellets (not shown) of a resin material as a raw material resin into the injection cylinder 11.

[0038] The injection device 10 constructed as described above rotates the screw 13 by a metering motor (not shown), melts and mixes the resin material in the injection cylinder 11, and accumulates the molten resin in the vicinity of the nozzle 12 of the injection cylinder 11 to perform metering. The molten resin accumulated in the injection cylinder 11 is moved to the side where the nozzle 12 is located by the injection motor (not shown), the ball screw and the nut (not shown), so that the molten resin is injected from the nozzle 12. Thus, the injection device 10 injects the resin material melted in the injection cylinder 11 into the mold 25 arranged in the mold clamping device 20, and fills the molten resin into the cavity of the mold 25.

[0039] <Mold clamping device 20>

[0040] Figure 2 yes Figure 1 A side view of the clamping device 20 is shown. Figure 2 For Figure 1 1 is an explanatory diagram of the mold clamping device 20 in a state where the cover 6 is removed from the injection molding machine 1. In the description of the mold clamping device 20, the "advancement" of each element of the mold clamping device 20 refers to the direction in which the mold clamping device 20 is located toward the injection device 10 in the longitudinal direction Y ( Figure 2 In addition, the "retraction" of each element of the mold clamping device 20 refers to the movement in the opposite direction (in the longitudinal direction Y) relative to the direction in which the mold clamping device 20 is located toward the injection device 10. Figure 2 ) to the left of .

[0041] The mold clamping device 20 includes, for example, a fixed mold 21 fixed to the frame 5 , a movable mold 22 arranged to face the fixed mold 21 and capable of approaching or moving away from the fixed mold 21 , and a link housing 30 movably arranged on the frame 5 .

[0042] A mold 25 for molding a resin material injected from the injection device 10 is mounted on the fixed mold 21 and the movable mold 22. A fixed mold 26 of a pair of molds 25 consisting of a fixed mold 26 and a movable mold 27 is mounted on the fixed mold 21, and a movable mold 27 of a pair of molds 25 is mounted on the movable mold 22. The movable mold 22 on which the movable mold 27 is mounted is arranged in an orientation such that the movable mold 27 faces the fixed mold 26 mounted on the fixed mold 21. Specifically, the movable mold 22 is arranged on the side opposite to the side on which the injection device 10 is arranged in the longitudinal direction Y with respect to the fixed mold 21, and the movable mold 22 and the fixed mold 21 are arranged in an orientation such that the movable mold 27 mounted on the movable mold 22 faces the fixed mold 26 mounted on the fixed mold 21 in the longitudinal direction Y.

[0043] The connecting rod housing 30 is arranged on the side of the movable mold 22 opposite to the side where the fixed mold 21 is arranged in the longitudinal direction Y. That is, the fixed mold 21, the movable mold 22 and the connecting rod housing 30 are arranged in the order of the fixed mold 21, the movable mold 22 and the connecting rod housing 30 in the longitudinal direction Y from the side where the injection device 10 is located.

[0044] A plurality of tie rods 70 are arranged between the fixed mold 21 and the connecting rod housing 30. In the present embodiment, four tie rods 70 are arranged. The tie rod 70 is formed in a rod-like shape extending in the longitudinal direction Y, one end of which is fixed to the fixed mold 21 and the other end of which is connected to the connecting rod housing 30. Thus, the fixed mold 21 and the connecting rod housing 30 are connected via the tie rod 70. On the other hand, the tie rod 70 is not connected to the movable mold 22 arranged between the fixed mold 21 and the connecting rod housing 30, and the tie rod 70 passes through the movable mold 22 in the longitudinal direction Y. When the mold 25 is tightened and the mold is closed, the tie rod 70 is stretched in the longitudinal direction Y by the mold opening and closing mechanism 40 described later, and the mold closing force can be generated by its reaction force.

[0045] The tie bar sensors 75 are mounted on the tie bars 70. The tie bar sensors 75 are mounted on each of the four tie bars 70. The tie bar sensors 75 are, for example, strain sensors, and can detect the elongation of the tie bars 70 in the extending direction, that is, the elongation of the tie bars 70 in the length direction Y. The tie bar sensors 75 that detect the elongation of the tie bars 70 can detect the magnitude of the mold clamping force when the mold opening and closing mechanism 40 clamps the mold 25 by detecting the elongation of the tie bars 70. In addition, the tie bar sensors 75 may not be mounted on all of the four tie bars 70, and the tie bar sensors 75 may be mounted on only one of the four tie bars 70, for example.

[0046] The mold opening and closing mechanism 40 includes a toggle link 41 and a drive device 50. The toggle link 41 can be connected to the link case 30 and the movable mold 22 to change the distance between the link case 30 and the movable mold 22 in the longitudinal direction Y, and the drive device 50 can operate the toggle link 41.

[0047] The driving device 50 includes a ball screw 51, a cross head 52, a nut 53, and a mold clamping motor 60 (see Figure 3 The ball screw 51 penetrates the connecting rod housing 30 in the longitudinal direction Y, and is mainly arranged to extend in the longitudinal direction Y from the connecting rod housing 30 toward the side where the movable mold 22 is located.

[0048] The nut 53 is mounted on the crosshead 52, and the crosshead 52 and the nut 53 are arranged between the connecting rod housing 30 and the movable die 22. The nut 53 mounted on the crosshead 52 is screwed on the ball screw 51 between the connecting rod housing 30 and the movable die 22. As a result, the crosshead 52 is rotated by the ball screw 51, and can be integrated with the nut 53 screwed on the ball screw 51 and move in the longitudinal direction Y. In addition, a guide portion (not shown) for guiding the crosshead 52 is provided on the crosshead 52, and when the crosshead 52 moves in the longitudinal direction Y along the ball screw 51, it moves while being guided by the guide portion.

[0049] Figure 3 yes Figure 2 AA view. The mold clamping motor 60 is mounted on the connecting rod housing 30, and in the present embodiment is mounted on the side surface of the connecting rod housing 30 in the width direction X. The mold clamping motor 60 is, for example, a servo motor, and is capable of driving the ball screw 51 via the first pulley 61, the timing belt 63, and the second pulley 62 in sequence. In detail, the first pulley 61 is mounted on the output shaft of the mold clamping motor 60. In addition, the second pulley 62 is mounted on the end of the ball screw 51 on the opposite side of the connecting rod housing 30 on the side where the movable mold 22 is located. The timing belt 63 is wound between these first pulleys 61 and the second pulley 62, and transmits the driving force generated by the mold clamping motor 60 and transmitted from the first pulley 61 to the timing belt 63 to the ball screw 51 via the second pulley 62.

[0050] The ball screw 51 is rotated by the driving force generated by the mold clamping motor 60 and transmitted to the ball screw 51 via the first pulley 61, the timing belt 63, and the second pulley 62. The nut 53 threaded with the ball screw 51 moves linearly in the longitudinal direction Y along the ball screw 51, and the cross head 52 formed integrally with the nut 53 moves linearly in the longitudinal direction Y along the ball screw 51 together with the nut 53.

[0051] The link housing 30 and the movable mold 22 are connected to each other by a toggle link 41 provided in the mold opening and closing mechanism 40. The toggle link 41 includes a crosshead side link 42, a link housing side link 43, and a movable mold side link 44. The link housing side link 43 is rotatably connected to the link housing 30 at an end on one side of the link housing 30 in the longitudinal direction Y, and is rotatably connected to the movable mold side link 44 at an end on the opposite side. The movable mold side link 44 is rotatably connected to the movable mold 22 at an end on the opposite side of the end on one side of the link housing 30 in the longitudinal direction Y via a toggle link connection portion 45.

[0052] Therefore, the link rod 43 on the link housing side and the link rod 44 on the movable die side can be rotated by the respective connection parts, so that the distance in the length direction Y between the end of the link rod 43 on the side connected to the link rod housing 30 and the end of the movable die side link rod 44 on the side connected to the movable die 22 can be changed. Thus, the link rod 43 on the link housing side and the movable die side link rod 44 connected to the link rod housing 30 and the movable die 22 can change the distance in the length direction Y between the link rod housing 30 and the movable die 22.

[0053] Furthermore, the crosshead side link 42 has one end rotatably connected to the crosshead 52 and the other end rotatably connected to the link housing side link 43. Therefore, the crosshead side link 42 can transmit the movement of the crosshead 52 moving in the longitudinal direction Y to the link housing side link 43. Thus, the crosshead side link 42 can operate the link housing side link 43 and the movable die side link 44 that rotatably connect the respective connection parts.

[0054] The toggle links 41 configured as above are arranged on both sides of the crosshead 52 in the vertical direction Z. That is, the toggle links 41 are arranged on both sides of the upper and lower sides of the crosshead 52 in the vertical direction Z, and the link housing 30 and the movable die 22 are connected via the upper and lower toggle links 41 .

[0055] The toggle link 41 has a crosshead side link 42 connected to a crosshead 52, and the crosshead 52 is arranged to be movable along the ball screw 51 in the longitudinal direction Y by the driving force generated by the mold clamping motor 60. Therefore, the toggle link 41 transmits the movement of the crosshead 52 moving in the longitudinal direction Y to the crosshead side link 42 by the driving force generated by the mold clamping motor 60, and the link housing side link 43 and the movable mold side link 44 that freely connect the respective connection parts are operated. The drive device 50 can operate the toggle link 41 by the driving force generated by the mold clamping motor 60.

[0056] The mold opening and closing mechanism 40 can move the movable mold 22 relative to the link housing 30 in the longitudinal direction Y by operating the toggle link 41 through the driving device 50. Thus, the mold opening and closing mechanism 40 can relatively move the movable mold 27 mounted on the movable mold 22 relative to the fixed mold 26 mounted on the fixed mold 21 in the longitudinal direction Y, and can open, close and clamp the movable mold 27 and the fixed mold 26.

[0057] When the mold opening and closing mechanism 40 performs mold closing or mold clamping of the fixed mold 26 and the movable mold 27, the mold clamping motor 60 advances the crosshead 52 to extend the mold opening and closing mechanism 40. That is, by driving the mold clamping motor 60, the ball screw 51 is rotated in a predetermined direction via the timing belt 63, so that the nut 53 screwed on the ball screw 51 and the crosshead 52 integrally provided with the nut 53 are advanced in the direction where the fixed mold 21 is located in the longitudinal direction Y. At this time, the upper link housing side link 43 and the movable mold side link 44 are opened upward, and the lower link housing side link 43 and the movable mold side link 44 are opened downward, and the movement of the crosshead 52 is transmitted to the movable mold 22 via the toggle link 41. Thus, the mold closing or mold clamping of the fixed mold 26 and the movable mold 27 is performed.

[0058] Furthermore, when the mold opening of the fixed mold 26 and the movable mold 27 is performed, on the contrary, the crosshead 52 is retracted by the mold clamping motor 60, and the link 43 on the link case side and the link 44 on the movable mold side are bent. That is, by driving the mold clamping motor 60, the ball screw 51 is rotated in the opposite direction to the mold closing through the timing belt 63, and the nut 53 and the crosshead 52 are retracted in the direction where the link case 30 is located in the longitudinal direction Y. In this way, by retracting the nut 53 in the direction where the link case 30 is located, the upper link case side link 43 and the movable mold side link 44 are closed downward, and the lower link case side link 43 and the movable mold side link 44 are closed upward, and the movement of the crosshead 52 is transmitted to the movable mold 22 via the toggle link 41. In this way, the mold opening of the fixed mold 26 and the movable mold 27 is performed.

[0059] Thus, in the present embodiment, in the state where the mold is closed or the mold clamping is completed, the link rod housing side link rod 43 and the movable mold side link rod 44 are substantially straight, and when the mold is opened, the link rod housing side link rod 43 and the movable mold side link rod 44 are bent toward the side where the axis of the ball screw 51 is located. That is, when the mold is opened, the link rod housing side link rod 43 and the movable mold side link rod 44 are bent to be rolled inward in the up-down direction Z.

[0060] The frame 5 is provided with a first linear guide 90 as a guide mechanism for guiding the movable die 22. The first linear guide 90 can guide the movement of the movable die 22 in the longitudinal direction Y. The first linear guide 90 includes a first guide rail 91 arranged on the frame 5 and extending in the longitudinal direction Y, and a first block 92 mounted on the movable die 22 and capable of moving along the first guide rail 91 while sliding relative to the first guide rail 91. The first guide rail 91 is arranged on the frame 5 at two locations near both ends of the movable die 22 in the width direction X, and is formed to extend toward both sides of the movable die 22 in the longitudinal direction Y. The first block 92 is arranged at two locations near both ends of the movable die 22 in the width direction X, and the two first blocks 92 are mounted on the movable die 22 at a distance in the width direction X that is substantially the same as the distance of the first guide rail 91.

[0061] Furthermore, the frame 5 is provided with a second linear guide 95 as a guide mechanism for guiding the link housing 30. The second linear guide 95 can guide the movement of the link housing 30 in the longitudinal direction Y. The second linear guide 95 includes a second guide rail 96 arranged on the frame 5 and extending in the longitudinal direction Y, and a second block 97 mounted on the link housing 30 and movable along the second guide rail 96 while sliding relative to the second guide rail 96. The second guide rail 96 is arranged on the frame 5 at two locations near both ends of the link housing 30 in the width direction X, and is formed to extend toward both sides of the link housing 30 in the longitudinal direction Y. The second block 97 is arranged at two locations near both ends of the link housing 30 in the width direction X, and the two second blocks 97 are mounted on the link housing 30 at a distance in the width direction X that is substantially the same as the distance of the second guide rail 96.

[0062] In addition, the first guide rail 91 of the first linear guide portion 90 and the second guide rail 96 of the second linear guide portion 95 may be continuously formed to constitute the same guide rail.

[0063] The four tie rods 70 connecting the fixed mold 21 and the connecting rod housing 30 are respectively connected to two locations near both ends in the width direction X and two locations near both ends in the vertical direction Z of the fixed mold 21 and the connecting rod housing 30 (see Figure 3 That is, the four tie rods 70 are connected to four locations near both ends in the width direction X and near both ends in the up-down direction Z of the fixed mold 21 and the link housing 30, respectively.

[0064] A threaded portion 71 is formed on the outer peripheral surface of the tie rod 70 disposed in this manner near the end portion thereof connected to the link case 30 (see FIG. 1 ). Figure 4). With regard to the tie rod 70 and the connecting rod housing 30 , a tie rod nut 81 that is threadedly engaged with the threaded portion 71 of the tie rod 70 is disposed on the connecting rod housing 30 , and the tie rod 70 and the connecting rod housing 30 are connected by the tie rod nut 81 .

[0065] Figure 4 yes Figure 2 A detailed cross-sectional view of the connection portion between the tie rod 70 and the connecting rod housing 30 is shown. Figure 4 Detailed view of the connection portion between one tie rod 70 and the connecting rod housing 30, and the four tie rods 70 are formed in the same manner. The tie rod nut 81 is arranged on the opposite side of the connecting rod housing 30 in the thickness direction, that is, the longitudinal direction Y, of the connecting rod housing 30, where the fixed die 21 and the movable die 22 are arranged. A flange portion 81b is formed on the outer peripheral surface of the tie rod nut 81, which protrudes outward in the radial direction of the tie rod nut 81.

[0066] A nut support member 82 for supporting the tie rod nut 81 is disposed on the surface side of the connecting rod housing 30 on the side where the tie rod nut 81 is disposed in the thickness direction. The nut support member 82 is mounted on the connecting rod housing 30 with the flange portion 81b of the tie rod nut 81 sandwiched between the nut support member 82 and the connecting rod housing 30. The nut support member 82 mounted on the connecting rod housing 30 supports the tie rod nut 81 rotatably while restricting the flange portion 81b of the tie rod nut 81 from leaving the connecting rod housing 30 in the longitudinal direction Y. Thus, the tie rod nut 81 is rotatably disposed on the connecting rod housing 30.

[0067] Furthermore, a thrust washer 83 is disposed between the flange portion 81b of the tie rod nut 81 and the connecting rod housing 30 to receive the force between the tie rod nut 81 and the connecting rod housing 30 in the longitudinal direction Y. Thus, the tie rod nut 81 can rotate even when a load in the longitudinal direction Y is applied between the tie rod nut 81 and the connecting rod housing 30.

[0068] The connecting rod housing 30 has a through hole 31 through which the tie rod 70 is inserted. The through hole 31 has an inner diameter that is approximately the same as the outer diameter of the tie rod 70 and is formed to penetrate the connecting rod housing 30 in the thickness direction of the connecting rod housing 30, that is, in the longitudinal direction Y. The tie rod 70 is inserted into the through hole 31 formed in the connecting rod housing 30 and connected to the connecting rod housing 30.

[0069] The tie rod nut 81 is disposed in a portion of the through hole 31 formed in the connecting rod housing 30 that is open on the surface on the opposite side to the side where the fixed die 21 and the movable die 22 are disposed in the longitudinal direction Y. The tie rod nut 81 disposed on the connecting rod housing 30 via the nut support member 82 has a threaded portion 81a formed as a female thread on the inner peripheral surface. On the other hand, the threaded portion 71 of the tie rod 70 is a male thread, and thus, in the tie rod nut 81, the threaded portion 81a of the tie rod nut 81 is screwed into the threaded portion 71 of the tie rod 70.

[0070] Since the threaded portion 81 a of the tie bar nut 81 is screwed together with the threaded portion 71 of the tie bar 70 in this manner, the tie bar nut 81 can be relatively moved in the longitudinal direction Y, which is the extending direction of the tie bar 70 , with respect to the tie bar 70 by rotating the tie bar nut 81 .

[0071] Furthermore, the tie rod nut 81 is disposed on the connecting rod housing 30, and the connecting rod housing 30 is disposed on the frame 5 via the second linear guide 95 that guides the movement of the connecting rod housing 30 in the longitudinal direction Y. Therefore, when the tie rod nut 81 is rotated, the connecting rod housing 30 on which the tie rod nut 81 is disposed can also move in the longitudinal direction Y while being guided by the second linear guide 95 by the tie rod nut 81 moving relative to the tie rod 70 in the longitudinal direction Y.

[0072] In this way, the tie rod nut 81 that can move the connecting rod housing 30 in the longitudinal direction Y by rotating relative to the tie rod 70 constitutes the mold thickness adjustment mechanism 80. In addition to the tie rod nut 81, the mold thickness adjustment mechanism 80 also includes a mold thickness adjustment motor 84, a drive gear 85, a ring gear 86, and a tie rod nut gear 87 (see Figure 2 , Figure 3 ).

[0073] The tie rod nut gears 87 are respectively mounted on the four tie rod nuts 81 screwed with the four tie rods 70. The annular gear 86 is configured to mesh with the four tie rod nut gears 87. The drive gear 85 is mounted on the output shaft of the mold thickness adjustment motor 84 and is configured to mesh with the annular gear 86 to drive the annular gear 86. The mold thickness adjustment motor 84 is, for example, a servo motor and is provided as a power source for the mold thickness adjustment mechanism 80. The mold thickness adjustment motor 84 is mounted on the connecting rod housing 30, and in this embodiment, is mounted on the side surface of the connecting rod housing 30 in the width direction X.

[0074] The mold thickness adjustment mechanism 80 constructed as described above is driven by the mold thickness adjustment motor 84 to rotate the drive gear 85. The rotating drive gear 85 rotates the four tie rod nut gears 87 in the same direction via the ring gear 86, and rotates the four tie rod nuts 81 in the same direction. When the tie rod nut 81 rotates, the tie rod nut 81 moves relative to the tie rod 70 in the longitudinal direction Y together with the connecting rod housing 30. Therefore, when the tie rod nut 81 rotates, the mold thickness adjustment mechanism 80 having the tie rod nut 81 is integrated with the connecting rod housing 30 and moves relative to the tie rod 70 in the longitudinal direction Y.

[0075] Here, the mold opening and closing mechanism 40 is arranged on the link housing 30, and the link housing 30 is connected to the movable mold 22 via the toggle link 41 included in the mold opening and closing mechanism 40. In addition, the movable mold 22 is arranged on the frame 5 via the first linear guide 90 that guides the movement of the movable mold 22 in the longitudinal direction Y. Therefore, when the link housing 30 moves in the longitudinal direction Y by the mold thickness adjustment mechanism 80, the movable mold 22 connected to the link housing 30 via the toggle link 41 also moves in the longitudinal direction Y as a whole with the link housing 30 while being guided by the first linear guide 90.

[0076] Since the movable mold 27 is mounted on the movable mold 22, when the movable mold 22 moves in the longitudinal direction Y, the distance between the movable mold 27 mounted on the movable mold 22 and the fixed mold 26 mounted on the fixed mold 21 changes. Thus, the mold thickness adjustment mechanism 80 can adjust the relative position of the movable mold 27 and the fixed mold 26.

[0077] As described above, the mold thickness adjustment mechanism 80 can adjust the relative positions of the movable mold 27 and the fixed mold 26 mounted on the movable mold 22 connected to the link housing 30 via the toggle link 41 by rotating the tie rod nut 81 to move the link housing 30 and the tie rod nut 81 relative to the tie rod 70 in the extending direction of the tie rod 70. Therefore, when replacing the mold 25, for example, the mold thickness adjustment mechanism 80 moves the link housing 30 and the movable mold 27 in the longitudinal direction Y according to the thickness of the mold 25 in the longitudinal direction Y, so that the distance between the fixed mold 26 and the movable mold 27 in the longitudinal direction Y can be appropriately adjusted. In addition, in the present embodiment, the rotation of the tie rod nut 81 advancing along the tie rod 70 when the tie rod nut 81 is rotated is referred to as "positive rotation". In contrast, the rotation of the tie rod nut 81 retreating along the tie rod 70 when the tie rod nut 81 is rotated is referred to as "reverse rotation" in the present embodiment.

[0078] In addition, the injection molding machine 1 has a control device 100 that performs various controls of the injection molding machine 1. The control device 100 has a CPU (Central Processing Unit) that performs calculation processing, a RAM (Random Access Memory) and a ROM (Read Only Memory) that function as a memory for storing various information, etc. All or part of the functions of the control device 100 are realized by loading the application program stored in the ROM into the RAM and executing it by the CPU, thereby reading and writing data in the RAM and ROM.

[0079] The control device 100 is connected to a display unit 101 that displays various information of the injection molding machine 1 and an input unit 102 used when an operator performs input operations on the injection molding machine 1. The display unit 101 connected to the control device 100 displays information transmitted from the control device 100, and the input unit 102 transmits information of the input operation to the control device 100.

[0080] The injection molding machine 1 is provided with various sensors for detecting various states of the injection molding machine 1 during operation, and these sensors are connected to the control device 100. The control device 100 controls the operation of the injection molding machine 1 by controlling various actuators of the injection molding machine 1 based on the detection results from these sensors.

[0081] For example, the tie bar sensor 75 disposed on the tie bar 70 is connected to the control device 100 and can send the detection result to the control device 100. In addition, the mold clamping motor 60 of the mold opening and closing mechanism 40 and the mold thickness adjustment motor 84 of the mold thickness adjustment mechanism 80 are equipped with encoders (omitted in the figure), and these encoders are also connected to the control device 100 and can send the detection result to the control device 100.

[0082] Furthermore, a heater (not shown) disposed on the injection cylinder 11 of the injection device 10, a mold clamping motor 60 of the mold opening and closing mechanism 40, and a mold thickness adjustment motor 84 of the mold thickness adjustment mechanism 80 are also connected to the control device 100 and are operated by control signals from the control device 100. Thus, the control device 100 can control the injection device 10, the mold opening and closing mechanism 40 of the mold clamping device 20, and the mold thickness adjustment mechanism 80.

[0083] <Function of injection molding machine 1>

[0084] The injection molding machine 1 according to the present embodiment includes the above-described configuration, and its operation will be described below. The control device 100 controls the drive device 50 and the mold thickness adjustment mechanism 80 of the mold clamping device 20 described below.

[0085] Figure 5 1 is an explanatory diagram of an injection molding cycle performed by an injection molding machine 1. First, the overall flow of the injection molding process is briefly described. Figure 5As shown, the injection molding machine 1 of the present embodiment performs an injection molding cycle S100. The injection molding machine 1 performs injection molding by controlling the actuators of the injection molding machine 1 by the control device 100 while obtaining the operating state of each part of the injection molding machine 1 from the detection results of the sensors. The injection molding cycle S100 when the injection molding machine 1 performs injection molding specifically includes a mold clamping step S101, an injection step S102, a metering and cooling step S103, a mold opening step S104, and a product removal step S105. By repeating these steps in sequence, a large number of molded products are produced.

[0086] Next, the operation of the mold clamping device 20 in the mold clamping step S101 will be described. Figure 6 2 is an explanatory diagram of the operation of the mold clamping device 20 in the mold clamping process. Figure 6 As shown in (a), the mold clamping device 20 is in a mold open state in which the movable mold 27 is separated from the fixed mold 26.

[0087] In the mold clamping process S101, the mold clamping device 20 performs mold closing and mold clamping of the mold 25 from the mold open state. When performing mold closing of the mold 25, the control device 100 drives the mold clamping motor 60 of the mold opening and closing mechanism 40 of the mold clamping device 20 to advance the crosshead 52. As a result, the link housing side link 43 and the movable mold side link 44 of the toggle link 41 extend. That is, by driving the mold clamping motor 60, the ball screw 51 rotates in a predetermined direction via the timing belt 63, and the nut 53 and the crosshead 52 screwed with the ball screw 51 advance in the direction where the fixed mold 21 is located in the longitudinal direction Y.

[0088] When the crosshead 52 moves in the longitudinal direction Y, the movement of the crosshead 52 is transmitted to the link housing side link 43 via the crosshead side link 42 of the toggle link 41. As a result, the upper toggle link 41 moves in the direction in which the link housing side link 43 and the movable die side link 44 open upward in the vertical direction Z, and the lower toggle link 41 moves in the direction in which the link housing side link 43 and the movable die side link 44 open downward in the vertical direction Z.

[0089] Since the end of the movable die side link 44 opposite to the end connected to the link housing side link 43 is connected to the movable die 22, when the link housing side link 43 and the movable die side link 44 move in the opening direction, the movable die 22 moves forward along with the movement of the movable die side link 44. When the die is closed, the movement of the crosshead 52 in the longitudinal direction Y is transmitted to the movable die 22 via the toggle link 41, and the movable die 22 moves toward the side where the fixed die 21 is located in the longitudinal direction Y.

[0090] The movable die 22 has a movable die 27 mounted on the surface on the side where the fixed die 21 is located. On the other hand, the fixed die 26 is mounted on the surface on the side where the movable die 22 is located on the fixed die 21. Therefore, when the movable die 22 moves toward the side where the fixed die 21 is located in the longitudinal direction Y, the movable die 27 mounted on the movable die 22 abuts against the fixed die 26 mounted on the fixed die 21. In this way, the mold closing (molding of the fixed die 26 and the movable die 27) is performed by the movable die 27 mounted on the movable die 22 abutting against the fixed die 26 mounted on the fixed die 21. Figure 6 (b)).

[0091] When the fixed mold 26 and the movable mold 27 are in contact and the mold is closed, the tie bar 70 slightly extends in the longitudinal direction Y. The extension of the tie bar 70 is detected by the tie bar sensor 75 attached to the tie bar 70 and transmitted to the control device 100. Thus, the control device 100 detects that the mold is closed between the fixed mold 26 and the movable mold 27.

[0092] Once the fixed mold 26 and the movable mold 27 are closed, the control device 100 further drives the mold clamping motor 60 of the mold opening and closing mechanism 40 of the mold clamping device 20 to further advance the crosshead 52. As a result, the movable mold 27 is pressed against the fixed mold 26, and the fixed mold 26 and the movable mold 27 are clamped ( Figure 6 (c)).

[0093] At this time, the tie rod 70 further extends slightly in the longitudinal direction Y. That is, when the mold clamping motor 60 is driven to extend the link housing side link 43 and the movable mold side link 44 of the toggle link 41 to push the movable mold 27 against the fixed mold 26, the distance between the link housing 30 and the movable mold 22 increases due to the extension of the toggle link 41, so that the link housing 30 moves slightly in the longitudinal direction Y to the side opposite to the side where the fixed mold 21 is located.

[0094] Since the end of the tie rod 70 on the opposite side of the end fixed to the fixed die 21 is connected to the connecting rod housing 30 by the tie rod nut 81, when the connecting rod housing 30 moves in the longitudinal direction Y to the side opposite to the side where the fixed die 21 is located, the tie rod 70 slightly extends in the longitudinal direction Y along with the movement of the connecting rod housing 30. Thus, the extension amount δ of the tie rod 70 when the tie rod 70 is extended is, for example, about 1 to 5 mm. That is, when the tie rod 70 is extended, the connecting rod housing 30 moves to the side opposite to the side where the fixed die 21 is located in the longitudinal direction Y while being guided by the second linear guide 95, and the tie rod 70 extends according to the movement amount of the connecting rod housing 30.

[0095] Since both ends of the tie rod 70 are connected to the fixed die 21 and the connecting rod housing 30, when the tie rod 70 is extended, a contraction force acts on the fixed die 21 and the connecting rod housing 30. That is, a contraction reaction force is generated in the extended tie rod 70, and the contraction force of the tie rod 70 acts on the fixed die 21 and the connecting rod housing 30 as a force in a direction to reduce the distance between the two in the longitudinal direction Y.

[0096] Since the movable mold 22 on which the movable mold 27 is mounted is connected to the link housing 30 via the toggle link 41, when the force of the tie rod 70 to contract acts on the fixed mold 21 and the link housing 30, the force acts as a force that pushes the movable mold 27 mounted on the movable mold 22 toward the fixed mold 26 mounted on the fixed mold 21. As a result, a force that pushes the fixed mold 26 and the movable mold 27 in the longitudinal direction Y, that is, a clamping force, is generated.

[0097] On the other hand, in the mold opening step S104, the mold clamping device 20 moves the crosshead 52 backward in the longitudinal direction Y through the mold opening and closing mechanism 40, bends the link 43 on the link housing side and the link 44 on the movable mold side, and molds the fixed mold 26 and the movable mold 27. That is, the control device 100 drives the mold clamping motor 60 provided in the mold opening and closing mechanism 40 of the mold clamping device 20, rotates the ball screw 51 in the opposite direction when the mold is closed via the timing belt 63, and moves the nut 53 and the crosshead 52 screwed with the ball screw 51 backward in the direction in which the link housing 30 is located in the longitudinal direction Y.

[0098] When the crosshead 52 retreats, the upper toggle link 41 moves in the direction in which the link case side link 43 and the movable die side link 44 are closed downward in the vertical direction Z, and the lower toggle link 41 moves in the direction in which the link case side link 43 and the movable die side link 44 are closed upward in the vertical direction Z. As a result, the movable die 22 connected to the link case 30 via the toggle link 41 retreats to the side where the link case 30 is located in the longitudinal direction Y, and the mold opening of the fixed die 26 and the movable die 27 is performed.

[0099] As described above, in the injection molding machine 1 related to the present embodiment, when the mold is closed and the mold clamping is completed, the link housing side link 43 and the movable mold side link 44 of the toggle link 41 are substantially straight. In addition, when the mold is opened, the link housing side link 43 and the movable mold side link 44 are bent toward the side where the axis of the ball screw 51 is located, that is, bent in the up-down direction Z to be rolled inside.

[0100] Next, the mold thickness adjustment method by the mold thickness adjustment mechanism 80 is described. The mold thickness adjustment by the mold thickness adjustment mechanism 80 is performed, for example, when the mold 25 mounted on the fixed mold 21 and the movable mold 22 is replaced. That is, the mold clamping force by the mold opening and closing mechanism 40 extends the tie rod 70 in a state where the link rod housing side link 43 and the movable mold side link 44 are in a substantially straight line, and the maximum mold clamping force is generated. On the other hand, the mold 25 mounted on the fixed mold 21 and the movable mold 22 may have different thicknesses in the longitudinal direction Y depending on the mold 25.

[0101] When the thickness of the mold 25 is different, in the mold clamping process, the fixed mold 26 and the movable mold 27 may come into contact before the link case side link 43 and the movable mold side link 44 become substantially straight, or the fixed mold 26 and the movable mold 27 may not come into contact even when the link case side link 43 and the movable mold side link 44 become substantially straight. In this case, in the mold clamping process, since an appropriate mold clamping force cannot be generated on the mold 25, when the mold 25 is replaced, the mold thickness adjustment mechanism 80 adjusts the timing of the fixed mold 26 and the movable mold 27 coming into contact in the mold clamping process corresponding to the state of the toggle link 41.

[0102] For example, when the thickness of the replaced mold 25 in the longitudinal direction Y is thinner than the thickness of the mold 25 before replacement, the control device 100 drives the mold thickness adjustment motor 84 of the mold thickness adjustment mechanism 80 to rotate the tie rod nut 81 in the forward direction, thereby moving the tie rod nut 81 to the side where the fixed mold 21 is located relative to the tie rod 70 in the longitudinal direction Y. That is, the control device 100 drives the mold thickness adjustment motor 84, rotates the ring gear 86 by the driving gear 85, and rotates the tie rod nut gear 87 by the ring gear 86, thereby rotating the tie rod nut 81 in the forward direction. As a result, the tie rod housing 30 is moved together with the tie rod nut 81 to the side where the fixed mold 21 is located, and the movable mold 22 connected to the tie rod housing 30 via the toggle link 41 is moved to the side where the fixed mold 21 is located. Therefore, the movable mold 22 can be brought closer to the fixed mold 21 according to the thinning of the thickness of the mold 25, and an appropriate mold clamping force can be generated in the mold clamping process.

[0103] On the contrary, when the thickness of the replaced mold 25 in the longitudinal direction Y is thicker than the thickness of the mold 25 before replacement, the control device 100 drives the mold thickness adjustment motor 84 of the mold thickness adjustment mechanism 80 to reversely rotate the tie rod nut 81, so that the tie rod nut 81 moves relative to the tie rod 70 to the opposite side of the side where the fixed mold 21 is located in the longitudinal direction Y. As a result, the connecting rod housing 30 is moved together with the tie rod nut 81 to the opposite side of the side where the fixed mold 21 is located, and the movable mold 22 connected to the connecting rod housing 30 via the toggle link 41 is moved to the opposite side of the side where the fixed mold 21 is located. Therefore, the movable mold 22 can be moved away from the fixed mold 21 according to the increase in the thickness of the mold 25, and an appropriate mold clamping force can be generated in the mold clamping process.

[0104] Next, a mold clamping method when the mold 25 is clamped by the injection molding machine 1 according to the present embodiment will be described. The clamping force generated in the clamping process of the mold 25 is generated by the reaction force of the elongated tie rod 70 to contract and the elongated tie rod 70 being transmitted to the mold 25. In this way, the elongation of the tie rod 70 in the clamping process advances the movable mold 22 through the toggle link 41 of the mold opening and closing mechanism 40, and after the fixed mold 26 and the movable mold 27 come into contact, the toggle link 41 is also extended to increase the distance between the link housing 30 and the movable mold 22, thereby causing the link housing 30 to retreat in the longitudinal direction Y.

[0105] As a result, the tie rod nut 81 disposed on the connecting rod housing 30 is also retracted together with the connecting rod housing 30, and the tie rod 70 screwed with the tie rod nut 81 is extended in the retracting direction in the longitudinal direction Y. The reaction force of the extended tie rod 70 to contract is transmitted to the fixed mold 21 and the movable mold 22, and is transmitted to the mold 25, thereby generating a clamping force.

[0106] When the mold clamping force is generated in the mold 25 by extending the tie rod 70, the tie rod nut 81 that is threadedly engaged with the tie rod 70 is extended, but a gap is sandwiched between the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70. That is, since there is a play between the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70, there is a gap between the two. Therefore, when there is no force between the tie rod nut 81 and the tie rod 70 that interacts with each other, the tie rod nut 81 is in a state of being lowered downward by its own weight.

[0107] Figure 7 It is a detailed view of the tie rod 70 and the tie rod nut 81. Figure 8 yes Figure 7 Detailed diagram of the Ba and Bb sections. Figure 8 (a) Figure 7 Detailed diagram of the Babu, Figure 8 (b) Figure 7 Detailed diagram of the Bb portion of the tie rod nut 81. When there is no interaction force between the tie rod nut 81 and the tie rod 70, the tie rod nut 81 is in a downwardly descending state due to its own weight. Therefore, in the upper portion of the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70, as shown in FIG. Figure 8 As shown in (a), the threaded portion 81a of the tie rod nut 81 is in contact with the threaded portion 71 of the tie rod 70. In contrast, in the lower portion of the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70, as shown in FIG. Figure 8 As shown in (b), the threaded portion 81 a of the tie rod nut 81 is in a state where a gap g in the up-down direction Z exists between the threaded portion 81 a and the threaded portion 71 of the tie rod 70 .

[0108] In this state, when the movable mold 22 is advanced by the toggle link 41 of the mold opening and closing mechanism 40 to bring the fixed mold 26 into contact with the movable mold 27, and the toggle link 41 is further extended to generate a mold clamping force in the mold 25, the reaction force caused by the mold clamping force is transmitted to the link housing 30 via the toggle link 41. That is, the force on the side opposite to the side where the fixed mold 21 is located in the longitudinal direction Y acts on the link housing 30 due to the mold clamping force, and this force acts from the link housing 30 to the tie nut 81 arranged on the link housing 30.

[0109] Fig. 9 This is a detailed view of the tie bar 70 and the tie bar nut 81 when a reaction force of the mold clamping force acts on the tie bar nut 81 in the conventional injection molding machine 1 . Fig.10 yes Fig. 9 Detailed diagram of the Ca and Cb parts. Fig.10 (a) Fig. 9 Detailed diagram of the Ca section, Fig.10 (b) Fig. 9 Detailed diagram of the Cb portion of FIG. In the conventional injection molding machine 1, when the mold 25 generates a mold clamping force in the mold clamping process, the reaction force of the mold clamping force acts on the tie rod nut 81 from the connecting rod housing 30, and a large force in the direction opposite to the direction in which the fixed mold 21 is located in the longitudinal direction Y acts on the tie rod nut 81. That is, in the mold clamping process, a large force in the backward direction in the longitudinal direction Y acts on the tie rod nut 81 due to the reaction force of the mold clamping force.

[0110] When the force in the backward direction in the longitudinal direction Y acts on the tie rod nut 81, in the upper portion of the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70, as shown in FIG. Fig.10 As shown in (a), the threaded portion 81a of the tie rod nut 81 moves along the thread of the threaded portion 71 of the tie rod 70, so that the tie rod nut 81 is lifted upward.

[0111] Therefore, in the threaded portion 81a of the tie rod nut 81 and the portion of the threaded portion 71 of the tie rod 70 located on the lower side, Fig.10 As shown in (b), there is no gap between the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70, and the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70 are in contact with each other over the entire circumference.

[0112] However, during the period when the tie nut 81 is lifted upward by the force in the backward direction caused by the reaction force of the mold clamping force, the threaded portion 81a of the tie nut 81 and the threaded portion 71 of the tie bar 70 have not yet reached a state of contact with each other over the entire circumference before the lifting is completed. That is, during the period before the tie nut 81 is completely lifted upward by the force in the backward direction caused by the reaction force of the mold clamping force, the threaded portion 81a of the tie nut 81 and the threaded portion 71 of the tie bar 70 are in an incomplete contact state. During this period, if the reverse rotation force generated by the force in the backward direction to reversely rotate the tie nut 81 becomes larger than the friction resistance at the contact portion between the threaded portion 81a of the tie nut 81 and the threaded portion 71 of the tie bar 70, the threaded portion 81a of the tie nut 81 moves in the reverse rotation direction along the spiral direction of the threaded portion 71 of the tie bar 70, and the tie nut 81 retreats along the tie bar 70.

[0113] In addition, while the tie nut 81 is moving backward along the tie rod 70 while rotating in the reverse direction, the force in the backward direction caused by the reaction force of the mold clamping force lifts the tie nut 81 upward. Therefore, when the tie nut 81 is completely lifted upward by the reaction force of the mold clamping force and the threaded portion 81a of the tie nut 81 and the threaded portion 71 of the tie rod 70 are in contact with each other over the entire circumference, the backward movement caused by the reverse rotation of the tie nut 81 stops.

[0114] The tie nut 81 is a component for adjusting the positions of the connecting rod housing 30 and the movable mold 22 in the longitudinal direction Y so that the mold 25 can generate a suitable clamping force. However, when the tie nut 81 moves in the longitudinal direction Y, the connecting rod housing 30 and the movable mold 22 also move together with the tie nut 81. In this case, it may be difficult for the mold 25 to generate a suitable clamping force in the clamping process when the injection molding machine 1 performs injection molding.

[0115] Fig.111 is an explanatory diagram showing the relationship between the movement of the crosshead 52 and the change of the mold clamping force Fc and the movement of the mold thickness adjustment motor 84 when the conventional injection molding machine 1 performs mold clamping. When the mold 25 is clamped by the injection molding machine 1, the crosshead 52 is advanced by the driving force generated by the mold clamping motor 60 of the mold opening and closing mechanism 40, and the toggle link 41 is operated to advance the movable mold 22 in the longitudinal direction Y. Therefore, when the mold 25 is clamped, the crosshead 52 is moved as shown in FIG. Fig.11 As shown, the crosshead moves in the longitudinal direction Y at a predetermined crosshead speed Sh.

[0116] When the mold 25 is being clamped, the control device 100 decelerates the crosshead speed Sh once the deceleration point T1 set by the clamping point Tm, which is the time point at which the clamping force Fc is generated based on the contact between the fixed mold 26 and the movable mold 27, is reached during the movement of the crosshead 52. In addition, the clamping point Tm and the deceleration point T1 can be set by time, position, or distance relative to the movement of the crosshead 52. The deceleration point T1 is set to a time point earlier than the clamping point Tm. In other words, the deceleration point T1 is set to a time point earlier than the clamping point Tm. In addition, the clamping point Tm is the time point at which the separated fixed mold 26 and the movable mold 27 contact when the mold closing and clamping of the mold 25 are controlled. The clamping point Tm and the deceleration point T1 are adjusted to match the mold thickness adjustment performed by the mold thickness adjustment mechanism 80.

[0117] In the conventional injection molding machine 1, the crosshead speed Sh is decelerated, and once the mold closing time point Tm is reached, Fig.11 As shown in FIG. 1 , the control device 100 increases the crosshead speed Sh. At this time, the control device 100 does not stop the crosshead 52, but adjusts the crosshead speed Sh while advancing the crosshead 52. That is, the control device 100 does not set the crosshead speed Sh to 0 but adjusts the crosshead speed Sh. In this way, by increasing the crosshead speed Sh by the control device 100, the tie rod 70 is extended, and the reaction force to the extension of the tie rod 70 acts on the mold 25, so the mold clamping force Fc increases. Once the mold clamping force Fc increases to a certain extent, the control device 100 reduces the crosshead speed Sh to maintain the mold clamping force Fc.

[0118] Here, when the crosshead speed Sh is increased rapidly while the crosshead 52 is advanced, the tie rod nut 81 is easily reversely rotated. That is, when the crosshead speed Sh is increased rapidly while the crosshead 52 is advanced, the tie rod 70 is rapidly extended, and the reaction force of the mold clamping force Fc generated by the mold 25 acts rapidly on the tie rod nut 81 from the tie rod housing 30.

[0119] Thus, the tie rod nut 81, which is in a state of falling downward by its own weight, is acted upon by a force in the backward direction in the longitudinal direction Y, as shown in FIG. Fig.10 As shown in FIG. 1 , the upper portion of the threaded portion 81a contacts the threaded portion 71 of the tie rod 70, and the tie rod nut 81 tends to rise along the thread of the threaded portion 71 of the tie rod 70. Furthermore, while the force in the backward direction caused by the reaction force of the mold clamping force acts rapidly on the tie rod nut 81, the reverse rotation force generated by the force in the backward direction to reversely rotate the tie rod nut 81 becomes larger. Therefore, the reverse rotation force of the tie rod nut 81 becomes larger than the friction resistance at the contact portion between the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70, and the threaded portion 81a of the tie rod nut 81 moves in the reverse rotation direction along the spiral of the threaded portion 71 of the tie rod 70, and the tie rod nut 81 retreats along the tie rod 70.

[0120] However, while the tie nut 81 is retreating along the tie rod 70, the tie nut 81 is lifted upward by the force in the retreating direction caused by the reaction force of the mold clamping force. Therefore, when the tie nut 81 is lifted up and the threaded portion 81a of the tie nut 81 and the threaded portion 71 of the tie rod 70 are in contact with each other over the entire circumference, the retreat of the tie nut 81 due to the reverse rotation stops. After the retreat of the tie nut 81 due to the reverse rotation stops, the cross head 52 moves, and the mold clamping force Fc increases without causing a decrease due to the reverse rotation of the tie nut 81.

[0121] In the conventional injection molding machine 1, the reverse rotation of the tie rod nut 81 when the mold clamping force is generated is as follows: Fig.11 As shown, it is also represented by the mold thickness adjustment motor speed Sa which is the rotation speed of the mold thickness adjustment motor 84. That is, when the tie rod nut 81 performs reverse rotation, the reverse rotation of the tie rod nut 81 is transmitted from the tie rod nut gear 87 to the ring gear 86, and from the ring gear 86 to the drive gear 85, and then transmitted to the mold thickness adjustment motor 84.

[0122] Thus, during injection molding by the injection molding machine 1, the mold thickness adjustment motor 84 rotates in the reverse direction as indicated by Sar along with the reverse rotation of the tie nut 81 that rotates when the mold clamping force is generated in the mold 25. That is, the reverse rotation of the tie nut 81 when the mold clamping force is generated in the mold 25 is also indicated by the mold thickness adjustment motor speed Sa.

[0123] During injection molding by the injection molding machine 1, if the tie rod nut 81 is unnecessarily rotated in the reverse direction, the distance between the fixed mold 26 and the connecting rod housing 30 in the length direction Y changes, and accordingly, the distance between the fixed mold 26 and the movable mold 27 in the length direction Y changes, so it is sometimes difficult for the mold 25 to generate an appropriate amount of clamping force.

[0124] On the other hand, in the injection molding machine 1 according to the present embodiment, when the mold 25 is clamped, the clamping force Fc is increased after applying preload to the mold 25, thereby suppressing unnecessary reverse rotation of the tie nut 81.

[0125] Fig.12 This is an explanatory diagram showing the relationship between the movement of the crosshead 52 and the change of the mold clamping force Fc when the injection molding machine 1 according to the embodiment performs mold clamping, and the movement of the mold thickness adjustment motor 84. In the injection molding machine 1 according to the present embodiment, when the mold 25 is closed by the mold opening and closing mechanism 40 from the state where the mold 25 is opened to perform mold clamping, first, the control device 100 decelerates the mold clamping motor 60 at the deceleration time point T1 preset based on the mold clamping time point Tm, thereby decelerating the crosshead speed Sh.

[0126] Next, the control device 100 rotates the mold clamping motor 60 at a slow speed just before the movable mold 27 and the fixed mold 26 come into contact. That is, the control device 100 decelerates the mold clamping motor 60 at the deceleration time point T1, and once the crosshead speed Sh is decelerated, the mold clamping motor 60 is rotated in the slow speed rotation mode Ms. As a result, the movable mold 27 mounted on the movable mold 22 is approached to the fixed mold 26 at a slow speed. The moving speed of the movable mold 27 when approaching the fixed mold 26 at a slow speed is preferably within a range of 2.0 mm / s or more and 7.0 mm / s or less, for example.

[0127] The control device 100 stops the mold clamping motor 60 for a predetermined period by making the movable mold 27 approach the fixed mold 26 at a slow speed. The contact between the movable mold 27 and the fixed mold 26 is detected by the control device 100 based on the detection result of the tie bar sensor 75 installed on the tie bar 70. That is, while the movable mold 27 moves at a slow speed, the movable mold 27 contacts the fixed mold 26, and the parting surface between the movable mold 27 and the fixed mold 26 is closed. When the mold 25 is closed, the tie bar 70 is slightly extended.

[0128] The tie bar sensor 75 detects the slight extension of the tie bar 70 and outputs it as a low pressure mold clamping force detection signal to the control device 100. The control device 100, which has obtained the low pressure mold clamping force detection signal from the tie bar sensor 75, controls the mold clamping motor 60 to stop in a predetermined period P, that is, the pre-pressure mode Mp.

[0129] Specifically, when the mold clamping motor 60 is rotated in the slow rotation mode Ms and the movable mold 27 is brought close to the fixed mold 26 at a slow speed, once the control device 100 obtains the low-pressure mold clamping force detection signal from the tie bar sensor 75, the control device 100 further decelerates the rotation of the mold clamping motor 60 from the time point T2 when the low-pressure mold clamping force detection signal is obtained. As a result, the crosshead speed Sh also decreases after the time point T2 when the low-pressure mold clamping force detection signal is obtained.

[0130] Here, since the time point T2 when the low-pressure mold clamping force detection signal is obtained is the time point when the fixed mold 26 and the movable mold 27 are in contact, the crosshead 52 is also continuously moved at a slow speed before the rotation of the mold clamping motor 60 stops after the time point T2 when the low-pressure mold clamping force detection signal is obtained, so that the mold clamping force Fc of the mold 25 is slightly increased as the crosshead 52 moves.

[0131] The rotation of the mold clamping motor 60 is decelerated, and once the rotation speed of the mold clamping motor 60 becomes 0, the control device 100 shifts to the pre-pressure mode Mp, and stops the mold clamping motor 60 for a predetermined period P. In other words, the control device 100 sets the rotation speed of the mold clamping motor 60 to 0, and stops the mold clamping motor 60 for a predetermined period P after the lapse of an arbitrary deceleration period as a period until the mold clamping motor 60 is stopped, after the time point T2 at which the low-pressure mold clamping force detection signal is acquired.

[0132] In the pre-pressure mode Mp, the control device 100 applies a pre-pressure of a clamping force Fc much smaller than the maximum clamping force Fc during injection molding to the mold 25. The control device 100 uses the clamping force Fc in the range of 2.0% to 5.0% of the maximum clamping force applied to the mold 25 by the mold opening and closing mechanism 40 as the pre-pressure during the predetermined period P when the clamping motor 60 is stopped.

[0133] Thus, in the period from the time point T2 when the low-pressure mold clamping force detection signal is obtained to the time point when the mold clamping motor 60 stops rotating, the pre-pressure applied to the mold 25 in the pre-pressure pattern Mp becomes the mold clamping force Fc of the mold 25 which is slightly increased while the mold clamping motor 60 is gradually decelerated. Therefore, the magnitude of the pre-pressure can be adjusted by adjusting the time required from the time point T2 when the low-pressure mold clamping force detection signal is obtained to the time point when the mold clamping motor 60 stops rotating.

[0134] In addition, the predetermined period P during which the mold clamping motor 60 is stopped in the pre-pressing mode Mp is about 0.3 seconds in the present embodiment. That is, the control device 100 applies pre-pressing to the mold 25 for about 0.3 seconds in the pre-pressing mode Mp. In addition, the predetermined period P during which the mold clamping motor 60 is stopped in the pre-pressing mode Mp is preferably within the range of 0.3 seconds to 1.0 seconds.

[0135] When the predetermined period P has passed while the mold 25 is pre-pressed, the control device 100 increases the rotation speed of the mold clamping motor 60 after the predetermined period P has passed, and performs mold clamping of the mold 25. That is, in the present embodiment, the time point when the predetermined period P has passed in the pre-pressing mode Mp is the mold clamping time point Tm, and when the predetermined period P has passed while the mold 25 is pre-pressed, the control device 100 increases the rotation speed of the mold clamping motor 60 and increases the crosshead speed Sh. As a result, the tie rod 70 is extended, and the reaction force to the extension of the tie rod 70 acts on the mold 25, so that the mold clamping force Fc increases. When the mold clamping force Fc increases to a certain extent, the control device 100 decreases the crosshead speed Sh to maintain the mold clamping force Fc.

[0136] In the present embodiment, before the mold clamping force Fc is increased at the mold clamping time point Tm, a pre-pressure is applied to the mold 25. The pre-pressure applied to the mold 25 is a mold clamping force Fc that is much smaller than the maximum mold clamping force Fc, but when the pre-pressure is applied, a reaction force of the mold clamping force Fc corresponding to the pre-pressure acts on the tie rod nut 81 from the connecting rod housing 30.

[0137] Thus, the tie rod nut 81, which is in a state of falling downward by its own weight, is subjected to the force in the backward direction in the longitudinal direction Y, as shown in FIG. Fig.10 As shown, the upper portion of the threaded portion 81a contacts the threaded portion 71 of the tie rod 70, and the tie rod nut 81 rises along the thread of the threaded portion 71 of the tie rod 70. In addition, the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70 also contact the threaded portion 71 of the tie rod 70 in the lower portion, thereby achieving a state in which the threaded portion 81a and the threaded portion 71 are in contact with each other over the entire circumference. Therefore, the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70 are in a state in which friction is ensured.

[0138] On the other hand, since the reaction force of the mold clamping force Fc corresponding to the preload is much weaker than the maximum mold clamping force Fc, the force to the extent of reversely rotating the tie rod nut 81 does not act on the tie rod nut 81 from the connecting rod housing 30. Therefore, the tie rod nut 81 rises along the threaded portion 71 of the tie rod 70, and moves to the extent that the threaded portion 81a of the tie rod nut 81 is in contact with the threaded portion 71 of the tie rod 70 over the entire circumference.

[0139] In this embodiment, after the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70 are in contact over the entire circumference and the friction force is ensured between the two, the mold clamping force Fc is increased at the mold clamping time point Tm. Therefore, the reaction force of the mold clamping force acting on the tie rod nut 81 from the connecting rod housing 30 also increases, but at the time when the reaction force of the mold clamping force increases, the friction force between the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70 is ensured.

[0140] Therefore, even if the reaction force of the mold clamping force acting on the tie rod nut 81 from the connecting rod housing 30 increases, the tie rod nut 81 does not rotate in the reverse direction due to the friction between the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70, and the tie rod nut 81 remains stopped in the rotation direction. Fig.12 As shown, the mold thickness adjustment motor speed Sa is also maintained at 0.

[0141] In the present embodiment, when the mold 25 is clamped, the tie rod nut 81 does not rotate in the opposite direction due to the reaction force of the clamping force. Therefore, even if the injection molding of the injection molding machine 1 is repeated, the distance between the fixed mold 26 and the connecting rod housing 30 in the length direction Y does not change, and the distance between the fixed mold 26 and the movable mold 27 in the length direction Y does not change. Therefore, the mold 25 can continuously generate an appropriate clamping force.

[0142] <Effects of Implementation Methods>

[0143] In the mold clamping device 20 and the mold clamping method of the mold clamping device 20 of the above embodiment, when the mold 25 is closed by the mold opening and closing mechanism 40 to perform mold clamping, the mold clamping motor 60 is rotated at a slow speed just before the movable mold 27 and the fixed mold 26 come into contact, so that the movable mold 27 approaches the fixed mold 26 at a slow speed, and when the movable mold 27 and the fixed mold 26 come into contact, the mold clamping motor 60 is stopped for a predetermined period P. Thus, before the reaction force of the large mold clamping force acts on the tie rod nut 81 from the connecting rod housing 30, the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70 can be brought into contact over the entire circumference, thereby ensuring the frictional force between the two. The control device 100 ensures the frictional force between the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70 in this way, and after the predetermined period P has passed, the rotation speed of the mold clamping motor 60 is increased to perform mold clamping of the mold 25.

[0144] Thus, even when a large reaction force of the mold clamping force acts on the tie rod nut 81 from the connecting rod housing 30, the reverse rotation of the tie rod nut 81 can be suppressed by the friction force between the threaded portion 81a of the tie rod nut 81 and the threaded portion 71 of the tie rod 70. Therefore, even when the mold 25 is repeatedly clamped, the distance between the fixed mold 26 and the connecting rod housing 30 in the longitudinal direction Y does not change, so the magnitude of the mold clamping force generated by the mold 25 can be suppressed, and the mold 25 can continue to generate a mold clamping force of an appropriate magnitude. As a result, a decrease in the mold clamping force can be suppressed.

[0145] Furthermore, since the control device 100 applies a mold clamping force in the range of 2.0% to 5.0% of the maximum mold clamping force applied to the mold 25 by the mold opening and closing mechanism 40 during the predetermined period P when the mold clamping motor 60 is stopped, it is possible to ensure the friction force between the threaded portion 81a of the tie bar nut 81 and the threaded portion 71 of the tie bar 70 while suppressing the reverse rotation of the tie bar nut 81 due to the reaction force of the mold clamping force. Therefore, when the mold 25 is repeatedly clamped, it is possible to more reliably suppress the change in the magnitude of the mold clamping force generated by the mold 25. As a result, it is possible to suppress a decrease in the mold clamping force.

[0146] Furthermore, since the predetermined period P during which the mold clamping motor 60 is stopped is within a range of 0.3 seconds to 1.0 seconds, the threaded portion 81a of the tie bar nut 81 and the threaded portion 71 of the tie bar 70 can be more reliably brought into contact with each other over the entire circumference while suppressing the mold clamping process from being excessively prolonged, thereby ensuring the frictional force therebetween. Therefore, when the mold 25 is repeatedly clamped, the change in the magnitude of the mold clamping force generated by the mold 25 can be more reliably suppressed. As a result, a decrease in the mold clamping force can be suppressed.

[0147] Furthermore, since the injection molding machine 1 of the embodiment includes the injection device 10 and the above-mentioned mold clamping device 20, it is possible to suppress the reverse rotation of the tie nut 81 of the mold clamping device 20 during injection molding by the injection molding machine 1. Thus, even when the injection molding is repeatedly performed by the injection molding machine 1, it is possible to suppress the magnitude of the mold clamping force generated by the mold 25 from changing, and the mold 25 can continuously generate a mold clamping force of an appropriate magnitude. As a result, it is possible to suppress a decrease in the mold clamping force.

[0148] [Modifications]

[0149] In addition, in the above-mentioned embodiment, the mold opening and closing mechanism 40 transmits the driving force generated by the mold clamping motor 60 to the ball screw 51 by using the first pulley 61, the second pulley 62 and the timing belt 63, but the structure for transmitting the driving force generated by the mold clamping motor 60 to the ball screw 51 may be other than this. Similarly, the mold thickness adjustment mechanism 80 transmits the driving force generated by the mold thickness adjustment motor 84 to the tie nut 81 by using the driving gear 85, the ring gear 86 and the tie nut gear 87, but the structure for transmitting the driving force generated by the mold thickness adjustment motor 84 to the tie nut 81 may be other than this.

[0150] Furthermore, in the above-described embodiment, the mold clamping force generated in the mold 25 is detected by the tie bar sensor 75 disposed on the tie bar 70 , but the mold clamping force may be detected by a method other than the tie bar sensor 75 .

[0151] Description of symbols

[0152] 1…injection molding machine; 5…frame; 6…cover; 10…injection device; 11…injection cylinder; 12…nozzle; 13…screw; 14…accumulator; 20…mold clamping device; 21…fixed mold; 22…movable mold; 25…mold; 26…fixed mold; 27…movable mold; 30…connecting rod housing; 31…through hole; 40…mold opening and closing mechanism; 41…knuckle connecting rod; 42…crosshead side connecting rod; 43…connecting rod housing side connecting rod; 44…movable mold side connecting rod; 45…knuckle connecting rod connecting part; 50…driving device; 51…ball screw; 52…crosshead; 53…nut; 60…mold clamping motor; 61 …1st pulley; 62…2nd pulley; 63…timing belt; 70…tie rod; 71…threaded portion; 75…tie rod sensor; 80…mold thickness adjustment mechanism; 81…tie rod nut; 81a…threaded portion; 81b…flange portion; 82…nut supporting member; 83…thrust washer; 84…mold thickness adjustment motor; 85…drive gear; 86…ring gear; 87…tie rod nut gear; 90…1st linear guide; 91…1st guide rail; 92…1st block; 95…2nd linear guide; 96…2nd guide rail; 97…2nd block; 100…control device; 101…display unit; 102…input unit.

Claims

1. A mold clamping device, characterized in that: have: A fixed mold is installed to install the fixed mold in a pair of molds consisting of a fixed mold and a movable mold; A movable mold is installed on the movable mold and is arranged in a direction in which the movable mold is opposite to the fixed mold installed on the fixed mold; A connecting rod housing is arranged on the opposite side of the movable die to the side where the fixed die is arranged; a mold opening and closing mechanism comprising a toggle link connected to the link housing and the movable mold and capable of changing the distance between the link housing and the movable mold, and a mold clamping motor for actuating the toggle link, wherein the movable mold and the fixed mold mounted on the movable mold are opened, closed and clamped by actuating the toggle link with the driving force generated by the mold clamping motor to move the movable mold relative to the link housing; A tie rod, one end of which is fixed to the fixed mold and the other end of which is connected to the connecting rod housing; The mold thickness adjustment mechanism includes a tie rod nut which is threadedly engaged with a threaded portion formed on the other end side of the tie rod and is arranged on the connecting rod housing. By rotating the tie rod nut, the connecting rod housing and the tie rod nut are relatively moved relative to the tie rod in the extending direction of the tie rod, thereby adjusting the relative positions of the movable mold and the fixed mold installed on the movable mold connected to the connecting rod housing via the toggle connecting rod. as well as A control device for controlling the mold opening and closing mechanism and the mold thickness adjustment mechanism; When the control device closes the mold from the open state by the mold opening and closing mechanism to perform the mold closing, the control device rotates the mold closing motor at a slight speed just before the movable mold is about to contact the fixed mold, so that the movable mold approaches the fixed mold at a slight speed, and once the movable mold contacts the fixed mold, the mold closing motor is stopped for a specified period, and after the specified period has passed, the rotation speed of the mold closing motor is increased to perform the mold closing.

2. The mold clamping device according to claim 1, characterized in that: The control device applies the mold clamping force within a range of 2.0% to 5.0% of the maximum mold clamping force applied to the mold by the mold opening and closing mechanism to the mold during the predetermined period while the mold clamping motor is stopped.

3. The mold clamping device according to claim 1, characterized in that: The predetermined period during which the mold clamping motor is stopped is within a range of 0.3 seconds to 1.0 seconds.

4. An injection molding machine, characterized in that: have: The mold clamping device according to any one of claims 1 to 3; and The injection device melts the resin material in an injection cylinder having a screw disposed therein, and injects the molten resin material into the mold from a nozzle.

5. A mold clamping method, which is a mold clamping method using a mold clamping device, wherein the mold clamping device comprises: A fixed mold is installed to install the fixed mold in a pair of molds consisting of a fixed mold and a movable mold; A movable mold is installed on the movable mold and is arranged in a direction in which the movable mold is opposite to the fixed mold installed on the fixed mold; A connecting rod housing is arranged on the opposite side of the movable die to the side where the fixed die is arranged; a mold opening and closing mechanism comprising a toggle link connected to the link housing and the movable mold and capable of changing the distance between the link housing and the movable mold, and a mold clamping motor for actuating the toggle link, wherein the movable mold and the fixed mold mounted on the movable mold are opened, closed and clamped by actuating the toggle link with the driving force generated by the mold clamping motor to move the movable mold relative to the link housing; A tie rod, one end of which is fixed to the fixed mold and the other end of which is connected to the connecting rod housing; and The mold thickness adjustment mechanism includes a tie rod nut which is threadedly engaged with a threaded portion formed on the other end side of the tie rod and is arranged on the connecting rod housing. By rotating the tie rod nut, the connecting rod housing and the tie rod nut are relatively moved relative to the tie rod in the extending direction of the tie rod, thereby adjusting the relative positions of the movable mold and the fixed mold installed on the movable mold connected to the connecting rod housing via the toggle connecting rod. It is characterized in that When the mold is closed by the mold opening and closing mechanism from the open state to perform the mold closing, the mold closing motor is rotated at a slight speed just before the movable mold is about to contact the fixed mold, so that the movable mold approaches the fixed mold at a slight speed, and once the movable mold contacts the fixed mold, the mold closing motor is stopped for a specified period, and after the specified period has passed, the rotation speed of the mold closing motor is increased to perform the mold closing.

Images