A two-plate injection molding machine synchronous brake device

Abstract

This invention relates to the technical field of two-platen injection molding machine components, and more specifically, to a synchronous brake device for a two-platen injection molding machine. The device includes a first half-brake, a second half-brake, and a brake cylinder. The first and second half-brakes are arranged opposite each other, and the brake cylinder is located outside the second half-brake. The brake cylinder includes a cylinder body and a piston rod. The cylinder body is fixedly connected to the first half-brake via a pull rod, and the piston rod is fixedly connected to the second half-brake, allowing the piston rod to control the movement of the second half-brake. The device also includes a mounting plate fixedly connected to the high-pressure clamping cylinder of the two-platen injection molding machine. The mounting plate is equipped with a linkage mechanism, through which the first and second half-brakes are connected and can move apart or in opposite directions. This synchronous brake device for a two-platen injection molding machine solves the problem of asynchronous movement of the two half-brakes during the opening and closing process.

Description

Technical Field

[0001] This invention relates to the field of two-platen injection molding machine parts technology, and in particular to a synchronous brake device for a two-platen injection molding machine. Background Technology

[0002] The mold closing mechanism of a two-platen injection molding machine involves a rapid mold-moving cylinder bringing the moving platen closer to the fixed platen. When a certain position is reached, the system activates a brake device, causing the moving platen to engage and clamp tightly with the guide rod. Finally, a high-pressure clamping cylinder provides high-pressure clamping force to lock the mold. The brake device typically consists of two symmetrical half-brakes. The opening and closing of the brake device is achieved through the relative movement of the two half-brakes. However, during the opening and closing process, the uneven frictional forces on the two half-brakes can easily cause one half-brake to move first, leading to impacts or abnormal noises, and ultimately, brake device malfunction. Summary of the Invention

[0003] To address the issue of asynchronous movement of the two half-brakes during the opening and closing of the brake device, this application provides a synchronous brake device for a two-platen injection molding machine.

[0004] The present invention provides a synchronous brake device for a two-platen injection molding machine, which adopts the following technical solution:

[0005] A synchronous brake device for a two-platen injection molding machine includes a first half-brake, a second half-brake, and a brake cylinder. The first half-brake and the second half-brake are arranged opposite to each other. The brake cylinder is located outside the second half-brake. The brake cylinder includes a cylinder body and a piston rod. The cylinder body is fixedly connected to the first half-brake via a pull rod, and the piston rod is fixedly connected to the second half-brake, allowing the piston rod to control the movement of the second half-brake. The device also includes a mounting plate, which is fixedly connected to the high-pressure clamping cylinder of the two-platen injection molding machine. The mounting plate is equipped with a linkage mechanism, through which the first half-brake and the second half-brake are connected and can move apart or towards each other.

[0006] Preferably, the linkage mechanism includes a linkage rotating seat and connecting rods. The linkage rotating seat is rotatably mounted on the mounting plate via a rotating pin. Two connecting rods are provided. One end of each connecting rod is hinged to both ends of the linkage rotating seat via a first hinge pin. The other end of each connecting rod is hinged to the first half-brake and the second half-brake via a second hinge pin. The mounting plate is provided with a guide groove along the opening and closing direction of the brake device, and the guide groove allows the second hinge pin to pass through.

[0007] Preferably, it also includes a support plate, which is fixedly connected to the high-pressure clamping cylinder of the two-platen injection molding machine. The mounting plate and the support plate symmetrically abut against the first half-gate and the second half-gate. Limit blocks are provided at both the left and right ends of the mounting plate and the support plate. The limit blocks are set in the opening direction of the first half-gate and the second half-gate to limit the opening.

[0008] Preferably, the mounting plate and the support plate are provided with lubrication grooves on the side that contacts the first half-gate and the second half-gate, and the sidewalls of the mounting plate and the support plate are provided with oil injection holes that communicate with the lubrication grooves.

[0009] Preferably, the bottom of the tray is provided with an oil receiving tray.

[0010] Preferably, the cylinder body of the brake cylinder is provided with a first connector and a second connector, and the mounting plate is provided with a self-locking mechanism; oil entering through the first connector causes the piston rod to push the second half-brake to close the brake, and the self-locking mechanism locks the linkage rotary seat in the closed state; oil entering through the second connector causes the piston rod to pull the second half-brake to open the brake, and the unlocking of the self-locking mechanism is controlled by the oil entering through the second connector.

[0011] Preferably, the self-locking mechanism includes a lock seat, a lock tongue, and an elastic element. The lock tongue is connected to the lock seat through the elastic element, and the linkage rotary seat is provided with a lock hole. Before the linkage rotary seat is in the closed state, the lock tongue abuts against the linkage rotary seat under the action of the elastic element. When the linkage rotary seat is in the closed state, the lock tongue automatically engages in the lock hole under the action of the elastic element.

[0012] Preferably, the lock seat has an interconnected oil passage and a deformation groove. A control plate is provided in the deformation groove to isolate the oil passage and the deformation groove. The elastic element is connected between the inner end of the control plate and the bottom of the deformation groove. The lock tongue is connected to the outer end of the control plate through a connecting rod. The second connector enters and exits oil through the oil passage.

[0013] Preferably, the first half-brake and the second half-brake are respectively provided with a reflector and a distance sensor. The reflector and the distance sensor are arranged opposite to each other along the opening and closing direction. When the closing is completed, the distance sensor sends a stop signal to the oil inlet valve of the brake cylinder.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. When opening and closing the brake, the piston rod of the brake cylinder drives the second half brake to move. The second half brake drives the first half brake to move simultaneously through the linkage mechanism, so that the first half brake and the second half brake move towards each other or away from each other at the same time, achieving a synchronous effect and avoiding the problem of asynchronous movement of the two half brakes during the opening and closing process of the brake device.

[0016] 2. After closing the circuit, the linkage rotary seat achieves self-locking through the self-locking mechanism. At this time, the oil inlet valve of the brake cylinder can be closed, and no energy needs to be supplied, thus achieving energy saving. When opening the circuit, oil is supplied to the second connector to automatically unlock the self-locking mechanism, achieving the effect of rapid opening under self-locking conditions.

[0017] 3. When the brake cylinder enters through the first connector to push the piston rod to close the brake, the brake cylinder simultaneously exits through the second connector and the oil circuit until the first and second half brakes are closed. Under the action of the elastic element, the locking tongue of the self-locking mechanism automatically inserts into the locking hole of the linkage rotary seat to achieve self-locking. When the brake cylinder enters through the oil circuit and the second connector to push the piston rod to open the brake, under the reaction of the locking force, the oil pressure pushes the control plate to move towards the bottom of the deformation groove, thereby driving the locking tongue to leave the locking hole, so that the first and second half brakes can carry out the opening process until the first and second half brakes are opened. Attached Figure Description

[0018] Figure 1 This is an overall structural diagram of the synchronous brake device for the two-platen injection molding machine in Embodiment 1;

[0019] Figure 2 This is a structural diagram of the lower end of the mounting plate of the synchronous brake device for the two-platen injection molding machine in Embodiment 1;

[0020] Figure 3 This is a structural diagram of the upper end of the support plate of the synchronous brake device for the two-platen injection molding machine in Embodiment 1;

[0021] Figure 4 This is a partial structural diagram of the two-platen injection molding machine in Example 1;

[0022] Figure 5 This is an overall structural diagram of the synchronous brake device for the two-platen injection molding machine in Embodiment 2;

[0023] Figure 6 This is a cross-sectional view of the lock seat of the synchronous brake device for the two-platen injection molding machine in Embodiment 2;

[0024] Explanation of reference numerals in the attached drawings: 11. Moving template; 12. Guide rod; 13. High-pressure locking cylinder; 21. First half brake; 22. Second half brake; 23. Engaging teeth; 3. Holding brake cylinder; 31. Cylinder body; 311. First connector; 312. Second connector; 32. Piston rod; 41. Pull rod; 42. Connecting plate; 51. Mounting plate; 52. Support plate; 53. Guide groove; 54. Limit block; 55. Lubrication groove; 56. 57. Oil inlet hole; 61. Oil receiving tray; 62. Linkage rotating seat; 63. Rotating pin; 64. Connecting rod; 65. First hinge pin; 66. Second hinge pin; 7. Lock seat; 71. Deformation groove; 72. Spring; 73. Control board; 74. Connecting rod; 75. Lock tongue; 76. Oil passage; 77. First frame plate; 8. Lock hole; 81. Second frame plate; 82. Docking plate; 91. Reflector plate; 92. Distance sensor. Detailed Implementation

[0025] The following will be combined with the appendix Figure 1-6 The present invention will be further illustrated by the embodiments.

[0026] This embodiment discloses a synchronous brake device for a two-platen injection molding machine.

[0027] Example 1

[0028] Reference Figure 1 and Figure 4 The synchronous brake device of the two-platen injection molding machine includes a first half-brake 21, a second half-brake 22, and a brake cylinder 3 arranged sequentially from left to right. The brake cylinder 3 includes a cylinder body 31 and a piston rod 32. The cylinder body 31 of the brake cylinder 3 is fixedly connected to the first half-brake 21 via a pull rod 41, and the piston rod 32 of the brake cylinder 3 is fixedly connected to the second half-brake 22. The synchronous brake device of the two-platen injection molding machine also includes a mounting plate 51, which is fixedly connected to the high-pressure clamping cylinder 13 of the two-platen injection molding machine. The mounting plate 51 is provided with a linkage mechanism, through which the first half-brake 21 and the second half-brake 22 are connected and linked. When opening and closing the brake, the piston rod 32 of the brake cylinder 3 drives the second half-brake 22 to move, and the second half-brake 22 simultaneously drives the first half-brake 21 to move via the linkage mechanism, so that the first half-brake 21 and the second half-brake 22 move towards or away from each other simultaneously, achieving a synchronous effect and avoiding the problem of asynchronous movement of the two half-brakes during the opening and closing of the brake device.

[0029] Reference Figure 1The first half-brake 21 and the second half-brake 22 each have an arc-shaped groove on their opposing surfaces, and the arc-shaped grooves have engagement teeth 23 for engaging the guide rod 12 of the two-platen injection molding machine. The first half-brake 21 and the second half-brake 22 are closed when moving towards each other and opened when moving away from each other. There are two pull rods 41, which are arranged parallel to each other vertically. The same end of the two pull rods 41 is connected to the upper and lower ends of the first half-brake 21 respectively and is fixedly connected by screws. The other ends of the two pull rods 41 pass through the upper and lower ends of the second half-brake 22 and are connected to the connecting plate 42 and fixedly connected to the connecting plate 42 by screws. The cylinder body 31 of the brake cylinder 3 is connected to the side of the connecting plate 42 away from the second half-brake 22 and is fixedly connected by screws. The piston rod 32 of the brake cylinder 3 is connected to the side of the second half-brake 22 away from the engagement teeth 23 and is fixedly connected by screws. The cylinder body 31 of the brake cylinder 3 is provided with a first connector 311 and a second connector 312. The brake cylinder 3 receives oil through the first connector 311 to push the piston rod 32 to drive the first half brake 21 and the second half brake 22 to close the brake, while the second connector 312 discharges oil. The brake cylinder 3 receives oil through the second connector 312 to push the piston rod 32 to drive the first half brake 21 and the second half brake 22 to open the brake, while the first connector 311 discharges oil.

[0030] Reference Figure 1 and Figure 4The linkage mechanism includes a linkage rotating seat 61 and a connecting rod 63. The linkage rotating seat 61 is rotatably mounted on the mounting plate 51 via a rotating pin 62. The axis of the rotating pin 62 coincides with the center line of the linkage rotating seat 61, ensuring that the movement processes of both ends of the linkage rotating seat 61 are consistent. Furthermore, the axis of the rotating pin 62 intersects with the axis of the guide rod 12 of the two-platen injection molding machine, ensuring that the linkage mechanism can drive the first half-brake 21 and the second half-brake 22 to smoothly bite the guide rod 12 of the two-platen injection molding machine. Two connecting rods 63 are provided. One end of the two connecting rods 63 is hinged to both ends of the connecting rotary seat 61 through the first hinge pin 64, and the other end of the two connecting rods 63 is hinged to the first half brake 21 and the second half brake 22 through the second hinge pin 65. The rotating pin 62, the first hinge pin 64 and the second hinge pin 65 are parallel to each other. The mounting plate 51 has two guide grooves 53. The two second hinge pins 65 pass through the two guide grooves 53 respectively. The guide grooves 53 guide the second hinge pins 65 in the direction of opening and closing of the brake device. Therefore, the process of the brake cylinder 3 controlling the synchronous opening and closing of the first half-brake 21 and the second half-brake 22 is as follows: the piston rod 32 of the brake cylinder 3 drives the second half-brake 22 to move. The second half-brake 22 drives the linkage rotary seat 61 through the connecting rod 63 at its upper end. The linkage rotary seat 61 drives the first half-brake 21 to move through the connecting rod 63 at the upper end of the first half-brake 21, thereby realizing the synchronous movement of the first half-brake 21 and the second half-brake 22 towards or away from each other, so as to achieve synchronous opening and closing. In this process, when the piston rod 32 of the brake cylinder 3 pushes the second half-brake 22, the first half-brake 21 simultaneously pushes the brake cylinder 3 through the pull rod 41. When the piston rod 32 of the brake cylinder 3 pulls the second half-brake 22, the first half-brake 21 simultaneously pulls the brake cylinder 3 through the pull rod 41.

[0031] Reference Figure 1 and Figure 4 The synchronous brake device of the two-platen injection molding machine also includes a support plate 52, which is fixedly connected to the high-pressure clamping cylinder 13 of the two-platen injection molding machine. The mounting plate 51 and the support plate 52 are distributed vertically and respectively abut against the top and bottom of the first half brake 21 and the second half brake 22. Limiting blocks 54 are provided at both the left and right ends of the mounting plate 51 and the support plate 52. The lower end of the limiting block 54 on the mounting block extends into the opening path of the first half brake 21 and the second half brake 22, and the upper end of the limiting block 54 on the support plate 52 extends into the opening path of the first half brake 21 and the second half brake 22, so that the limiting block 54 limits the opening of the first half brake 21 and the second half brake 22 in the opening direction of the first half brake 21 and the second half brake 22.

[0032] Reference Figures 1 to 3Both the lower surface of the mounting plate 51 and the upper surface of the support plate 52 are provided with lubrication grooves 55, and the side walls of the mounting plate 51 and the support plate 52 are provided with oil injection holes 56 that communicate with the lubrication grooves 55. Lubricating oil can be injected into the lower surface of the mounting plate 51 and the upper surface of the support plate 52 through the oil injection holes 56, thereby reducing the friction between the first half-brake 21 and the second half-brake 22 during the opening and closing process. Furthermore, an oil receiving tray 57 is provided at the bottom of the support plate 52.

[0033] Reference Figure 4 A two-platen injection molding machine typically includes four guide rods 12, a moving platen 11 guided by the four guide rods 12, and four high-pressure clamping cylinders 13 connected to the moving platen 11 to clamp it. The four high-pressure clamping cylinders 13 allow the four guide rods 12 to pass through. In this embodiment, the synchronous brake device is fixedly connected to the high-pressure clamping cylinders 13 via a mounting plate 51 and a support plate 52. The number of synchronous brake devices is the same as the number of high-pressure clamping cylinders 13. When the moving platen 11 moves into position, the synchronous brake device first clamps the guide rods 12, and then the high-pressure clamping cylinders 13 provide high-pressure clamping force to the moving platen 11.

[0034] Example 2

[0035] Reference Figure 5 The difference between Embodiment 2 and Embodiment 1 is that the mounting plate 51 is equipped with a self-locking mechanism. This mechanism automatically locks the linkage rotary seat 61 when it is in the closed state. The unlocking of the self-locking mechanism is controlled by the oil inlet of the second connector 312. Since the linkage rotary seat 61 is self-locked by the self-locking mechanism after the circuit is closed, the oil inlet valve of the brake cylinder 3 can be closed at this time, eliminating the need for energy supply and achieving energy saving. When the circuit is opened, the second connector 312 supplies oil to automatically unlock the self-locking mechanism, thus achieving the effect of rapid opening under self-locking conditions.

[0036] Reference Figure 5The self-locking mechanism includes a lock seat 7, a lock tongue 75, and an elastic element. The lock tongue 75 is connected to the lock seat 7 through the elastic element. The linkage rotary seat 61 is provided with a lock hole 8. In this embodiment, the lock tongue 75 is cuboid in shape, and the lock hole 8 is a rectangular hole. The positional relationship between the locking tongue 75 and the lock hole 8 needs to be set as follows: Before the linkage rotary seat 61 is in the closed state, the locking tongue 75 and the lock hole 8 are misaligned, and the locking tongue 75 cannot enter the lock hole 8. At this time, the locking tongue 75 presses against the linkage rotary seat 61 under the action of the elastic element. The linkage rotary seat 61 is subjected to the frictional force of the locking tongue 75 pressing against it during rotation, but this frictional force is not enough to prevent the linkage rotary seat 61 from continuing to rotate. When the linkage rotary seat 61 is in the closed state, the locking tongue 75 is aligned with the lock hole 8, and the locking tongue 75 automatically embeds into the lock hole 8 under the action of the elastic element. At this time, the locking tongue 75 jams the linkage rotary seat 61, preventing the linkage rotary seat 61 from rotating, thereby realizing the self-locking of the linkage rotary seat 61. At this time, the linkage rotary seat 61 can only be unlocked by pulling the locking tongue 75 out of the lock hole 8 by external force.

[0037] Reference Figure 5 The lock seat 7 is mounted on the upper part of the linkage rotary seat 61 by two first mounting plates 77. The lock tongue 75 is located at the lower end of the lock seat 7. The linkage rotary seat 61 is mounted on the docking plate 82 by two second mounting plates 81. The docking plate 82 is located directly below the lock tongue 75. The lock hole 8 is opened on the top surface of the docking plate 82, and the center line of the lock hole 8 coincides with the axis of the rotating pin 62.

[0038] Reference Figure 5 and Figure 6The lock seat 7 has an oil passage 76 and a deformation groove 71 connected to each other. The oil passage 76 is horizontally opened, and the deformation groove 71 is vertically opened, with the deformation groove 71 located above the oil passage 76. The lower end of the deformation groove 71 is connected to the upper end of the oil passage 76. A control plate 73 is vertically slidably installed in the deformation groove 71 to form a spatial block between the oil passage 76 and the deformation groove 71. The elastic element is a spring 72, which is connected between the inner end of the control plate 73 and the bottom of the deformation groove 71. The locking tongue 75 is connected to the outer end of the control plate 73 through a connecting rod 74. The lower end of the lock seat 7 has a corresponding guide hole for the connecting rod 74 to slide. When the spring 72 is in a compressed state, it passes through the control plate 73 and the connecting rod 74 in sequence, allowing the locking tongue 75 to spring into the lock hole 8 or be pulled out of the lock hole 8 to unlock. Furthermore, in order to control the unlocking of the locking tongue 75 by the oil inlet of the second connector 312, the second connector 312 enters and exits oil through the oil passage 76. When the external oil inlet valve controls the piston rod 32 of the brake cylinder 3 to pull the second half brake 22 to open the brake, the oil must first pass through the oil passage 76 of the lock seat 7, and then enter the cylinder body 31 of the brake cylinder 3 through the second connector 312. Due to the locking force of the locking tongue 75, the linkage rotary seat 61 cannot rotate, causing the piston rod 32 to be unable to move. However, the oil passage 76 and the second connector 312 continue to supply oil. Therefore, under the reaction of the locking force, the oil pressure will push the control plate 73 to move towards the bottom of the deformation groove 71, thereby driving the locking tongue 75 to leave the lock hole 8 and complete the unlocking, so that the first half brake 21 and the second half brake 22 can continue to open the brake until the first half brake 21 and the second half brake 22 have completed the opening process.

[0039] Reference Figure 5 The first half-brake 21 and the second half-brake 22 are respectively equipped with a reflector 91 and a distance sensor 92. The reflector 91 and the distance sensor 92 are arranged opposite each other along the opening and closing direction. The distance between the reflector 91 and the distance sensor 92 changes with the opening and closing of the first half-brake 21 and the second half-brake 22, so that the distance sensor 92 can sense the change in distance between the first half-brake 21 and the second half-brake 22. The distance sensor 92 needs to be set so that when the distance sensor 92 senses that the distance between the first half-brake 21 and the second half-brake 22 is the distance to complete the closing process, the distance sensor 92 sends a stop signal to the oil inlet valve of the brake cylinder 3, so as to achieve the effect of automatically stopping the oil inlet valve of the brake cylinder 3 after the closing self-locking.

[0040] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A synchronous brake device for a two-platen injection molding machine, characterized in that: The system includes a first half-brake (21), a second half-brake (22), and a brake cylinder (3). The first half-brake (21) and the second half-brake (22) are arranged opposite to each other. The brake cylinder (3) is arranged outside the second half-brake (22). The brake cylinder (3) includes a cylinder body (31) and a piston rod (32). The cylinder body (31) of the brake cylinder (3) is fixedly connected to the first half-brake (21) through a pull rod (41). The piston rod (32) of the brake cylinder (3) is fixedly connected to the second half-brake (22) so that the piston rod (32) controls the movement of the second half-brake (22). The system also includes a mounting plate (51). The mounting plate (51) is fixedly connected to the high-pressure clamping cylinder (13) of the two-platen injection molding machine. The mounting plate (51) is provided with a linkage mechanism. The first half-brake (21) and the second half-brake (22) are connected through the linkage mechanism and can move apart or towards each other. The linkage mechanism includes a linkage rotating seat (61) and a connecting rod (63). The linkage rotating seat (61) is rotatably mounted on the mounting plate (51) via a rotating pin (62). There are two connecting rods (63). One end of each connecting rod (63) is hinged to both ends of the linkage rotating seat (61) via a first hinge pin (64). The other ends of each connecting rod (63) are hinged to the first half-brake (21) and the second half-brake (22) via a second hinge pin (65). The mounting plate (51) has a guide groove (53) along the opening and closing direction of the brake device. The guide groove (53) allows the second hinge pin (65) to pass through. The cylinder body (31) of the brake cylinder (3) is provided with a first connector (311) and a second connector (312), and the mounting plate (51) is provided with a self-locking mechanism; when oil is introduced into the first connector (311), the piston rod (32) pushes the second half brake (22) to close the brake, and the self-locking mechanism locks the linkage rotary seat (61) in the closed state; when oil is introduced into the second connector (312), the piston rod (32) pulls the second half brake (22) to open the brake, and the unlocking of the self-locking mechanism is controlled by the oil supply of the second connector (312); The self-locking mechanism includes a lock seat (7), a lock tongue (75), and an elastic element. The lock tongue (75) is connected to the lock seat (7) through the elastic element. The linkage rotary seat (61) is provided with a lock hole (8). Before the linkage rotary seat (61) is in the closed state, the lock tongue (75) abuts against the linkage rotary seat (61) under the action of the elastic element. When the linkage rotary seat (61) is in the closed state, the lock tongue (75) automatically embeds into the lock hole (8) under the action of the elastic element.

2. The synchronous brake device for a two-platen injection molding machine according to claim 1, characterized in that: It also includes a support plate (52), which is fixedly connected to the high-pressure clamping cylinder (13) of the two-platen injection molding machine. The mounting plate (51) and the support plate (52) are symmetrically abutting against the first half-gate (21) and the second half-gate (22). Limiting blocks (54) are provided at both the left and right ends of the mounting plate (51) and the support plate (52). The limiting blocks (54) are set in the opening direction of the first half-gate (21) and the second half-gate (22) to limit the opening.

3. The synchronous brake device for a two-platen injection molding machine according to claim 2, characterized in that: The mounting plate (51) and the support plate (52) are provided with lubrication grooves (55) on the side that contacts the first half-brake (21) and the second half-brake (22), and the side walls of the mounting plate (51) and the support plate (52) are provided with oil injection holes (56) that communicate with the lubrication grooves (55).

4. The synchronous brake device for a two-platen injection molding machine according to claim 3, characterized in that: The bottom of the tray (52) is provided with an oil receiving tray (57).

5. A synchronous brake device for a two-platen injection molding machine according to claim 4, characterized in that: The lock seat (7) has an oil passage (76) and a deformation groove (71) connected to each other. A control plate (73) is provided in the deformation groove (71) to isolate the oil passage (76) and the deformation groove (71). The elastic element is connected between the inner end of the control plate (73) and the bottom of the deformation groove (71). The lock tongue (75) is connected to the outer end of the control plate (73) through a connecting rod (74). The second connector (312) enters and exits oil through the oil passage (76).

6. A synchronous brake device for a two-platen injection molding machine according to claim 5, characterized in that: The first half-brake (21) and the second half-brake (22) are respectively provided with a reflector (91) and a distance sensor (92). The reflector (91) and the distance sensor (92) are arranged opposite to each other along the opening and closing direction. When the closing is completed, the distance sensor (92) sends a stop signal to the oil inlet valve of the brake cylinder (3).

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