Positioning welding tool for reverse insertion type power device in PCBA (Printed Circuit Board Assembly)

Abstract

The invention discloses a positioning and welding tool for a reverse insertion type power device in a PCBA in the technical field of circuit board welding, and the positioning and welding tool comprises a supporting frame, a bottom plate and a pressing plate, the bottom plate is arranged on a base of the supporting frame, the pressing plate is arranged above the bottom plate in parallel and is connected with the supporting frame through a lifting mechanism, and the pressing plate is arranged above the bottom plate. A plurality of supporting blocks used for positioning and bearing the PCBA board are arranged on the upper surface of the bottom board, and when the PCBA board is placed on the supporting blocks with the A face facing upwards, the distance between the B face of the PCBA board and the upper surface of the bottom board is the same as the distance between the B face of the PCBA board and the back face of the radiator after the PCBA board is actually assembled in the electric control box. And the PCBA board can be pressed and fixed on the supporting block by the pressing plate under the action of the lifting mechanism. The PCBA board is positioned and clamped by adopting the positioning and welding tool, the stress condition of the PCBA board installed in an electric control box can be simulated, the heat dissipation surfaces of all power devices are controlled on the same plane, the relative position relation between the power devices and the PCBA board is ensured, and therefore the welding precision of the power devices is improved.

Description

Technical Field

[0001] The invention relates to the technical field of circuit board welding, and in particular to a positioning welding tool for reverse plug-in power devices in PCBA. Background Art

[0002] At present, there are two ways to plug power devices into PCBA, which are related to PCB design. One is that all devices are on the A side of the PCB, which is positive plugging; the other is that only a few power devices are on the B side, and the pins are on the A side, which is opposite to other devices, which is reverse plugging. Figure 1 As shown. Reverse insertion can hang the heat sink outside the entire electric control box, providing more sufficient assembly space. At present, there is a process problem when welding reverse-inserted power devices on PCBA boards, that is, after the multiple pins of the power device are inserted into the pads of the PCBA board, they must be welded. The key is that the plastic package of the power device must be on the same plane, that is, each power device must be very tightly fitted with the fitting surface of the heat sink, otherwise it will accumulate heat due to insufficient heat dissipation, causing the power device to burn. There are currently two ways of welding, first welding and later welding.

[0003] 1. Soldering first: This is a common method in the industry, that is, use a bracket to hold all power devices, try to ensure that all power devices are on the same plane, and then the PCBA board has been welded before being assembled to the electric control box (the power device is lifted a little by this bracket to ensure the welding position), but it is actually very imprecise, because the plastic bracket has its own deformation due to the process problem. Then, after the power device is welded and installed in the electric control box, it will cause the power device to fit the back of the radiator. In fact, it is still an imprecise problem. There will be a large difference in the three directions of XYZ. At this time, if the two are directly locked by screws, the power device pins will be strained, or the plastic package will be warped, or there will be a gap with the fitting surface on the back of the radiator. Warping and gaps seriously affect the heat dissipation performance. At the same time, after the welding is completed, the bracket is fixed on the board. The bracket has a cost. Every board needs to be equipped with such a bracket, which is very inappropriate.

[0004] 2. Post-welding: That is, first install the PCBA board into the electric control box, and then weld it after the screw connection is completed. This is a relatively perfect way. In this way, there is no need for a bracket, and the pin position of the power device can be welded in the most accurate state. The top of the power device and the back of the radiator will fit more closely, and the heat dissipation effect will be better. However, the problem is that if the post-welding is performed, since the PCBA board is installed in the electric control box, the operation is very inconvenient; at the same time, after the PCBA board is assembled in the electric control box, since the radiator has been fixedly installed in the electric control box, the front of the power device and the back of the radiator are fitted, which will cause the A side of the PCBA board to be invisible, making it impossible for the operator to check the welding quality of the pins from the A side after welding (both sides must be checked); at the same time, when the PCBA board is installed and transferred, the power device that has not yet been welded may fall down; in addition, once the PCBA board is installed in the electric control box, it is not convenient for the PCBA board to be coated with three anti-corrosion coatings through the assembly line, so this operation method does not meet the efficiency of mass production and is too inefficient. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies existing in the welding of reverse-inserted power devices in existing PCBA boards, the technical problem to be solved by the present invention is to provide a positioning welding tool for reverse-inserted power devices in PCBA boards which can improve welding accuracy and welding efficiency.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A positioning welding tool for reverse plug-in power devices in PCBA, suitable for a PCBA board on which the power device is welded between the B surface of the PCBA board and a radiator, the PCBA board is provided with a first assembly hole and a second assembly hole, and is fixed in an electric control box by a screw passing through the first assembly hole, the power device is provided with a third assembly hole aligned with the second assembly hole, the radiator is provided with a fourth assembly hole aligned with the second assembly hole, the power device and the radiator are connected together by screws passing through the third assembly hole and the fourth assembly hole, the positioning welding tool comprises a support frame, a base plate and a pressing plate, the base plate is arranged on the base of the support frame, the pressing plate is arranged parallel to the top of the base plate, and is connected to the support frame through a lifting mechanism, the upper surface of the base plate is provided with a plurality of support blocks for positioning and carrying the PCBA board, when the PCBA board is placed on the support block with the A surface facing up, the distance from the B surface of the PCBA board to the upper surface of the base plate is the same as the distance from the B surface of the actual PCBA board to the back of the radiator after it is assembled in the electric control box, and the pressing plate can press and fix the PCBA board on the support block under the action of the lifting mechanism.

[0008] Furthermore, a plurality of first positioning holes aligned with the first assembly holes on the PCBA board are provided on the support block of the base, a plurality of first positioning columns are provided at the bottom of the pressure plate, and a shoulder is provided at the lower end of the first positioning column. When the pressure plate presses the PCBA board, the lower end of the first positioning column can be embedded in the first positioning hole after passing through the first assembly hole of the PCBA board, and the PCBA board is pressed onto the support block through the shoulder.

[0009] Furthermore, a plurality of second positioning columns are provided at the bottom of the pressure plate, and the second positioning columns are aligned with the second assembly holes on the PCBA board. A second-step pressure head is provided at the lower end of the second positioning column, and a step surface is provided at the end of the second-step pressure head. When the pressure plate presses the PCBA board, the end of the second-step pressure head can be embedded in the third assembly hole of the power device after passing through the second assembly hole of the PCBA board, and the step surface is pressed tightly against the A surface of the PCBA board.

[0010] Furthermore, a plurality of third positioning columns are provided at the bottom of the pressure plate, the second positioning column is aligned with the second assembly hole on the PCBA board, and a second-order pressure head or a third-order pressure head is detachably installed at the lower end of the third positioning column, and a step surface is provided at the end of the second-order pressure head. When the pressure plate presses the PCBA board, the end of the second-order pressure head can be embedded in the third assembly hole of the power device after passing through the second assembly hole of the PCBA board, and the step surface is pressed and fitted with the A surface of the PCBA board; two step surfaces are provided at the end of the third-order pressure head, and a second positioning hole is provided on the bottom plate. When the pressure plate presses the PCBA board, the end of the third-order pressure head can be embedded in the second positioning hole after passing through the second assembly hole of the PCBA board and the third assembly hole of the power device in sequence, and the two step surfaces are respectively pressed and fitted with the top surface of the power device and the A surface of the PCBA board.

[0011] Furthermore, for the power devices on the PCBA board that are not in direct contact with the back of the heat sink, a placeholder is provided on the upper surface of the base plate at a position corresponding to its position, and the upper and lower surfaces of the placeholder are respectively adapted to the bottom surface of the power device and the back of the heat sink. When the pressing plate presses the PCBA board, the placeholder is pressed and filled between the power device and the heat sink.

[0012] Furthermore, the base plate and the pressure plate include a plurality of models with different structures that are replaceable, and the models of the two correspond one to one, and a hollow structure is provided at the parts of the base plate and the pressure plate where no power devices are arranged.

[0013] Furthermore, a door-shaped limit frame is provided on the base of the support frame, and the bottom plate is slidably arranged in the door-shaped limit frame.

[0014] Furthermore, vertical guide rods are provided on both sides of the support frame, and the pressure plate is slidably arranged on the guide rods. The lifting mechanism is a hand-pushed pressure rod, a pneumatic rod, a hydraulic rod or an electric push rod, and its fixed part is arranged on the top of the support frame. Its lifting end is detachably connected to the pressure plate and can drive the pressure plate to slide up and down along the guide rods.

[0015] The beneficial effects of the present invention are as follows: the positioning welding tool is used to position and clamp the PCBA board, which can simulate the stress condition of the PCBA board installed in the electric control box, and control the heat dissipation surfaces of all power devices to be on the same plane, thereby ensuring the relative position relationship between the power device and the PCBA board, thereby improving the welding accuracy of the power device, and after the welding is completed, the PCBA board can also be conveniently inspected for welding quality, and external operations such as three-proof coating can be performed, which can avoid the problem of substandard position matching between the radiator and the power device, thereby improving the welding and assembly quality of the PCBA board. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure where the PCBA board is installed in the electric control box;

[0017] Figure 2 It is a schematic diagram of the structure of the present invention.

[0018] Marked in the figure are, 1-PCBA board, 2-power device, 3-heat sink, 4-support frame, 5-bottom plate, 6-pressing plate, 7-lifting mechanism, 11-first assembly hole, 12-second assembly hole, 21-third assembly hole, 31-fourth assembly hole, 41-base, 42-door-type limit frame, 43-guide rod, 51-support block, 52-first positioning hole, 53-second positioning hole, 54-placeholder block, 61-first positioning column, 62-second positioning column, 63-third positioning column, 64-second-order pressure head, 65-third-order pressure head. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings.

[0020] It should be noted that if there are directional indication terms in the present invention, such as up, down, left, right, front, and back directions and orientation terms, they are for the purpose of facilitating the description of the relative position relationship between components, and are not specific to the absolute position of the related components or the position relationship between components. They are only used to explain the relative position relationship and movement of the components in a certain posture. If the specific posture changes, the directional indication will also change accordingly. If there are terms related to quantity in the present invention, such as "multiple", "multiple", "several", etc., they specifically refer to two or more.

[0021] The present invention provides a positioning welding tool for reverse plug-in power devices in PCBA, which is suitable for welding the power device 2 on the PCBA board between the B surface of the PCBA board 1 and the heat sink 3. The assembly structure is as follows: Figure 1 As shown, the PCBA board 1 is provided with a first assembly hole 11 and a second assembly hole 12, and is fixed in the electric control box by screws passing through the first assembly hole 11, the power device 2 is provided with a third assembly hole 21 aligned with the second assembly hole 12, and the heat sink 3 is provided with a fourth assembly hole 31 aligned with the second assembly hole 12, wherein the second assembly hole 12 is a through hole with a larger aperture, which can be passed through by a screw, and the third assembly hole 21 and the fourth assembly hole 31 are both threaded holes, and the power device 2 and the heat sink 3 are connected together by screws passing through the third assembly hole 21 and the fourth assembly hole 31. The edge of the heat sink 3 will be supported by some edges of the electric control box, not just hung on the power device 2 by screws.

[0022] In order to ensure that all power devices 2 welded on the PCBA board 1 can be closely attached to the back of the heat sink 3, the present invention provides a positioning welding tool, such as Figure 2 As shown, it includes a support frame 4, a bottom plate 5 and a pressing plate 6. The bottom plate 5 is arranged on the base 41 of the support frame 4. The pressing plate 6 is arranged above the bottom plate 5 in parallel and connected to the support frame 4 through a lifting mechanism 7. The upper surface of the bottom plate 5 is provided with a plurality of supporting blocks 51 for positioning and carrying the PCBA board 1. Before welding, the power device 2 is first reversely inserted on the PCBA board 1, and then placed on the supporting block 51 with the A side facing upward. The height of the supporting block 51 satisfies that the distance between the B side of the PCBA board 1 and the upper surface of the bottom plate 5 is the same as the distance between the B side of the PCBA board 1 and the back of the radiator 3 after the actual PCBA board 1 is assembled in the electric control box. Finally, the pressing plate 6 is pushed downward by the lifting mechanism 7 to press and fix the PCBA board 1 on the supporting block 51. When the PCBA board 1 is pressed, the power device 2 located on the B side of the PCBA board 1 will be tightly attached to the upper surface of the base plate 5, thereby simulating the first stress state where the back of the radiator 3 fits the power device 2. At this time, welding can be performed to ensure that all power devices 2 must be on the same plane, and the subsequent assembly with the real radiator 3 can ensure the fitting effect.

[0023] Although the above structure ensures that all power devices 2 are on the same plane, the lifting mechanism 7 simply presses down the A surface of the PCBA board 1. This stress condition is not completely consistent with the stress state of the PCBA after being assembled and clamped in the electric control box in the actual situation, which may cause welding errors. Therefore, a further solution is that a plurality of first positioning holes 52 aligned with the first assembly holes 11 on the PCBA board 1 are provided on the support block 51 of the base 41, and a plurality of first positioning columns 61 are provided at the bottom of the pressing plate 6. The lower end of the first positioning column 61 is provided with a shoulder. When the pressing plate 6 presses the PCBA board 1, the lower end of the first positioning column 61 can be embedded in the first positioning hole 52 after passing through the first assembly hole 11 of the PCBA board 1, and the PCBA board 1 is pressed against the support block 51 through the shoulder. In this way, the pressed stress state of the PCBA board 1 being assembled in the electric control box can be truly simulated, and the welding of the pins under this stress state can be more accurate.

[0024] When determining the soldering position of the power device 2, in addition to considering the distance between the power device 2 and the PCBA board 1, it is also necessary to consider whether the third assembly hole 21 thereon is aligned with the second assembly hole 12 on the PCBA board 1, so that the screw can pass through the second assembly hole 12 when the heat sink 3 is subsequently assembled. Therefore, a further solution is that a plurality of second positioning columns 62 are provided at the bottom of the pressure plate 6, and the second positioning columns 62 are aligned with the second assembly holes 12 on the PCBA board 1, and a second-step pressure head 64 is provided at the lower end of the second positioning column 62, and the second-step pressure head 64 can be integrally formed with the second positioning column 62, and a step surface is provided at its end. That is, the second-step pressing head 64 includes two sections, the diameter of the lower section is smaller than the aperture of the second assembly hole 12, and is equivalent to the aperture of the third assembly hole 21, and the outer diameter of the upper section is larger than the aperture of the second assembly hole 12. In this way, when the pressing plate 6 presses the PCBA board 1, the end of the second-step pressing head 64 can be embedded in the third assembly hole 21 of the power device 2 after passing through the second assembly hole 12 of the PCBA board 1, and the step surface is pressed and fitted with the A surface of the PCBA board 1, so that all power devices 2 can be positioned in the Z direction on the PCBA board 1, thereby improving their welding accuracy.

[0025] Since there are many different types of power devices 2 on PCBA, such as rectifier bridge stack and IGBT, the number of their pins is generally small. When the pins of such devices are inserted into the soldering holes of the PCB for welding, their spatial limiting ability in the XY direction (i.e., the plane direction) is relatively poor; while the number of pins of the variable frequency IPM module is quite large, which results in that the device has been relatively evenly limited in the XY direction. Therefore, in order to better position different power devices 2, the preferred solution provided by the present invention is: a plurality of third positioning columns 63 are provided at the bottom of the pressure plate 6, the second positioning column 62 is aligned with the second assembly hole 12 on the PCBA board 1, and the lower end of the third positioning column 63 is detachably installed with a second-order pressure head 64 or a third-order pressure head 65, and the end of the second-order pressure head 64 is provided with a step surface. When the pressure plate 6 presses the PCBA board 1, the end of the second-order pressure head 64 can pass through the second assembly hole 12 of the PCBA board 1. The third-step pressing head 65 is provided with two step surfaces at the end, and the bottom plate 5 is provided with a second positioning hole 53. When the pressing plate presses the PCBA board 1, the end of the third-step pressing head 65 can be inserted into the second positioning hole 53 after passing through the second assembly hole 12 of the PCBA board 1 and the third assembly hole 21 of the power device 2 in sequence, and the two step surfaces are respectively pressed and fitted with the top surface of the power device 2 and the A surface of the PCBA board 1. The second-step pressing head 64 is the same as the above scheme, and the third-step pressing head 65 is a three-stage structure. The second positioning hole 53 is designed according to the positional relationship between the heat sink 3 and the power device 2 in the actual assembly structure. During the pressing process, the third-step pressing head 65 is inserted between the power device 2 and the second positioning hole 53, so that the third assembly holes 21 of all power devices 2 can be aligned with the fourth assembly holes 31 on the heat sink 3, thereby positioning the power device 2 in the XY direction, and further improving the welding accuracy. In actual application, whether to use the second-order pressure head 64 or the third-order pressure head 65 can be determined according to the type of power device 2 to be welded, that is, the number of pins.

[0026] In addition, for some special power devices 2 or heat sinks 3, for example, the heat dissipation surface of the power device 2 is not a plane, there may be a ceramic gasket, or the back of the heat sink 3 is irregular and not a plane, so the positioning of the power device 2 cannot be achieved directly by pressing the PCBA board 1. In this regard, the solution provided by the present invention is that for the power device 2 on the PCBA board 1 that is not directly in contact with the back of the heat sink 3, a placeholder 54 is provided on the upper surface of the bottom plate 5 at a position corresponding to its position, and the upper and lower surfaces of the placeholder 54 are respectively adapted to the bottom surface of the power device 2 and the back of the heat sink 3. When the pressing plate 6 presses the PCBA board 1, the placeholder 54 is pressed and filled between the power device 2 and the heat sink 3, thereby meeting the positioning requirements of the power device 2 and the PCBA board 1.

[0027] In order to improve the application scope of the present invention, the bottom plate 5 and the pressing plate 6 include a variety of models with different structures that can be replaced, and the models of the two are one-to-one corresponding. In order to save costs, the parts of the bottom plate 5 and the pressing plate 6 where the power device 2 is not arranged are provided with a hollow structure.

[0028] In order to facilitate the replacement of the bottom plate 5 and ensure its installation accuracy, a door-shaped limit frame 42 is provided on the base 41 of the support frame 4, and the bottom plate 5 is slidably arranged in the door-shaped limit frame 42. The door-shaped limit frame 42 refers to a structure in which only baffles are provided on the left and right sides and the back of the base 41, and the front is open. When the bottom plate 5 needs to be replaced, it only needs to be pulled out from the front like a drawer, and then the new bottom plate 5 is pushed back along the original path.

[0029] As for the lifting mode of the pressing plate 6, in order to improve the stability of its lifting, the preferred solution provided by the present invention is that vertical guide rods 43 are provided on both sides of the support frame 4, and the pressing plate 6 is slidably arranged on the guide rods 43. The lifting mechanism 7 can have various forms, such as a hand-pushing pressing rod, a pneumatic rod, a hydraulic rod or an electric push rod, etc., wherein the hand-pushing pressing rod can realize the locking function during pressing with the help of a locking mechanism such as a cam, and the pneumatic rod, the hydraulic rod and the electric push rod directly use the existing equipment with a locking function. The fixed part of the lifting mechanism 7 is arranged at the top of the support frame 4, and its lifting end is detachably connected to the pressing plate 6, so as to facilitate the replacement of pressing plates 6 of different models.

Claims

1. A positioning welding tool for reverse plug-in power devices in PCBA, suitable for a PCBA board where a power device (2) is welded between the B surface of the PCBA board (1) and a heat sink (3), the PCBA board (1) being provided with a first assembly hole (11) and a second assembly hole (12), and being fixed in an electric control box by screws passing through the first assembly hole (11), the power device (2) being provided with a third assembly hole (21) aligned with the second assembly hole (12), the heat sink (3) being provided with a fourth assembly hole (31) aligned with the second assembly hole (12), the power device (2) and the heat sink (3) being connected together by screws passing through the third assembly hole (21) and the fourth assembly hole (31), characterized in that: The positioning welding tool comprises a support frame (4), a base plate (5) and a pressing plate (6); the base plate (5) is arranged on a base (41) of the support frame (4); the pressing plate (6) is arranged above the base plate (5) in parallel and connected to the support frame (4) via a lifting mechanism (7); a plurality of supporting blocks (51) for positioning and carrying a PCBA board (1) are arranged on the upper surface of the base plate (5); when the PCBA board (1) is placed on the supporting blocks (51) with the A surface facing upward, the distance between the B surface of the PCBA board (1) and the upper surface of the base plate (5) is the same as the distance between the B surface of the PCBA board (1) and the back surface of the radiator (3) after the actual PCBA board (1) is assembled in the electric control box; the pressing plate (6) can press and fix the PCBA board (1) on the supporting blocks (51) under the action of the lifting mechanism (7).

2. A positioning welding tool for reverse plug-in power devices in PCBA as claimed in claim 1, characterized in that: The support block (51) of the base (41) is provided with a plurality of first positioning holes (52) aligned with the first assembly holes (11) on the PCBA board (1); the bottom of the pressing plate (6) is provided with a plurality of first positioning columns (61); the lower ends of the first positioning columns (61) are provided with shaft shoulders; when the pressing plate (6) presses the PCBA board (1), the lower ends of the first positioning columns (61) can be embedded in the first positioning holes (52) after passing through the first assembly holes (11) of the PCBA board (1), and the PCBA board (1) is pressed onto the support block (51) through the shaft shoulders.

3. A positioning welding tool for reverse plug-in power devices in PCBA as claimed in claim 1, characterized in that: A plurality of second positioning columns (62) are provided at the bottom of the pressing plate (6), the second positioning columns (62) are aligned with the second assembly holes (12) on the PCBA board (1), a second-step pressing head (64) is provided at the lower end of the second positioning column (62), and a step surface is provided at the end of the second-step pressing head (64), and when the pressing plate (6) presses the PCBA board (1), the end of the second-step pressing head (64) can be embedded in the third assembly hole (21) of the power device (2) after passing through the second assembly hole (12) of the PCBA board (1), and the step surface is pressed and fitted with the A surface of the PCBA board (1).

4. A positioning welding tool for reverse plug-in power devices in PCBA as claimed in claim 1, characterized in that: A plurality of third positioning columns (63) are provided at the bottom of the pressing plate (6), the second positioning column (62) is aligned with the second assembly hole (12) on the PCBA board (1), and a second-order pressure head (64) or a third-order pressure head (65) is detachably installed at the lower end of the third positioning column (63), and the end of the second-order pressure head (64) is provided with a step surface. When the pressing plate (6) presses the PCBA board (1), the end of the second-order pressure head (64) can be embedded in the third assembly hole (21) of the power device (2) after passing through the second assembly hole (12) of the PCBA board (1). 1), and the step surface is pressed and fitted with the A surface of the PCBA board (1); the end of the three-step pressing head (65) is provided with two step surfaces, and the bottom plate (5) is provided with a second positioning hole (53). When the pressing plate presses the PCBA board (1), the end of the three-step pressing head (65) can be inserted into the second positioning hole (53) after passing through the second assembly hole (12) of the PCBA board (1) and the third assembly hole (21) of the power device (2) in sequence, and the two step surfaces are pressed and fitted with the top surface of the power device (2) and the A surface of the PCBA board (1) respectively.

5. The positioning welding tool for reverse plug-in power devices in PCBA according to claim 1, characterized in that: For a power device (2) on the PCBA board (1) that is not in direct contact with the back side of the heat sink (3), a placeholder (54) is provided at a position on the upper surface of the base plate (5) corresponding to the position thereof, and the upper and lower surfaces of the placeholder (54) are respectively adapted to the bottom surface of the power device (2) and the back side of the heat sink (3); when the pressing plate (6) presses the PCBA board (1), the placeholder (54) is pressed and filled between the power device (2) and the heat sink (3).

6. A positioning welding tool for reverse plug-in power devices in PCBA according to any one of claims 1 to 5, characterized in that: The base plate (5) and the pressure plate (6) include a plurality of models with different structures that are replaceable, and the models of the two models correspond one to one. A hollow structure is provided at the parts of the base plate (5) and the pressure plate (6) where the power device (2) is not provided.

7. A positioning welding tool for reverse plug-in power devices in PCBA as claimed in claim 6, characterized in that: A door-shaped limiting frame (42) is provided on the base (41) of the support frame (4), and the bottom plate (5) is slidably arranged in the door-shaped limiting frame (42).

8. A positioning welding tool for reverse plug-in power devices in PCBA as claimed in claim 6, characterized in that: Vertical guide rods (43) are provided on both sides of the support frame (4), and the pressing plate (6) is slidably arranged on the guide rods (43). The lifting mechanism (7) is a hand-pushed pressing rod, a pneumatic rod, a hydraulic rod or an electric push rod, and its fixed part is arranged on the top of the support frame (4). Its lifting end is detachably connected to the pressing plate (6) and can drive the pressing plate (6) to slide up and down along the guide rods (43).

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