Wet process processing equipment and opening and closing actuating device of magnetic fixture of wet process processing equipment
By controlling the opening and closing of the magnetic clamp through a two-stage clamping method, the problem of excessive clamping kinetic energy leading to substrate damage is solved, thus achieving safe clamping of the substrate and reliability during the processing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- AMPOC FAR EAST CO LTD
- Filing Date
- 2025-05-16
- Publication Date
- 2026-04-24
AI Technical Summary
The magnetic clamps in existing wet processing equipment have excessive kinetic energy during the clamping process, which can easily cause fragile substrates such as glass substrates to be cracked or broken, especially at their fragile edges.
A two-stage clamping method is adopted. First, the magnetic clamp is in a half-open and half-clamped state, and then the clamping is completed in the second stage. The opening and closing of the magnetic clamp is controlled by the push structure and drive unit to reduce the clamping kinetic energy.
It effectively avoids substrate cracking or breakage, ensures the safety of the substrate during wet processing, and improves the reliability of processing equipment.
Smart Images
Figure CN224165109U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a device for opening and closing magnetic clamps in wet processing, and in particular to a wet processing equipment and its magnetic clamp opening and closing actuation device. Background Technology
[0002] For wet processing equipment that performs wet processing on upright substrates, the substrate to be processed is usually held upright by magnetic clamps to facilitate the transport of the suspended substrate along a predetermined transport path, and the wet processing is performed on the substrate along the transport path.
[0003] However, magnetic clamps mainly use magnets at their clamping ends to utilize the principle that magnets can magnetically attract each other, allowing the clamping ends, which are originally in a fully open state, to be instantly clamped into a closed state due to the attraction of opposite magnetism between the two magnets. The clamping kinetic energy from fully open to closed is relatively large. For more fragile substrates, such as glass substrates, this can cause the substrate to be cracked or broken, which has long been criticized. Moreover, the magnetic clamps are clamped at the more fragile edge of the substrate, making it even more prone to cracking or breaking. Utility Model Content
[0004] The purpose of this utility model is to provide a wet process equipment and its magnetic clamping fixture opening and closing actuation device, which mainly enables the clamping of the first magnetic clamping fixture in a pair of magnetic clamping fixtures to be carried out in two stages, so as to reduce the clamping kinetic energy of the magnetic clamping fixture and achieve the effect of avoiding cracking or crushing the substrate.
[0005] To achieve the above objectives, this utility model provides an opening and closing actuation device for a magnetic clamp, which is driven by a pair of drive units to control the opening and closing of a pair of magnetic clamps. Each magnetic clamp has a magnetic clamping end and a third end. The opening and closing actuation device includes: a pair of brackets, each of which is respectively provided with a drive unit; and a pair of push structures. Each push structure includes a base and a plurality of push members protruding from the base. The base of each push structure is slidably disposed on each of the brackets and is driven by each of the drive units to move relative to each other. The plurality of push members of each push structure includes a first push member, a second push member, and a third push member. The first push member and the third push member... The second pusher corresponds to the magnetic clamping end and the other end of one of the magnetic clamps, and the third pusher corresponds to the other end of the other magnetic clamp. Each drive unit drives each base to move relative to each bracket along with several pushers. The first pusher of each pusher structure pushes the magnetic clamping end of one of the magnetic clamps to clamp and close, so that the other end can open from a closed position to a fully open position. The second pusher of each pusher structure blocks the other end of one of the magnetic clamps between the closed position and the fully open position. The third pusher of each pusher structure pushes the other end of the other magnetic clamp.
[0006] This utility model also provides a wet processing equipment, comprising: a carrier including a frame, an upper crossbar and a lower crossbar, the upper crossbar and the lower crossbar spanning within the frame and each provided with at least a pair of magnetic clamps, each magnetic clamp having a magnetic holding end and an other end; and two opening and closing actuation devices respectively configured corresponding to the upper crossbar and the lower crossbar, each opening and closing actuation device comprising: a pair of brackets, each provided with a drive unit; and a pair of pushing structures, each pushing structure comprising a base and a plurality of pushing members protruding from the base, the base of each pushing structure being slidably disposed on each of the brackets and driven by each of the drive units to move relative to each other, and the plurality of pushing members of each pushing structure including a first pushing member. A second pusher and a third pusher are provided, the first pusher and the second pusher respectively corresponding to the magnetic clamping end and the other end of one of the magnetic clamps, and the third pusher corresponding to the other end of the other magnetic clamp; wherein, each drive unit drives each base to move together with several pushers relative to each bracket, the first pusher of each pusher structure pushes the magnetic clamping end of one of the magnetic clamps to clamp and relative to each other so that the other end can open from a closed position to a fully open position, the second pusher of each pusher structure blocks the other end of one of the magnetic clamps between the closed position and the fully open position, and the third pusher of each pusher structure pushes the other end of the other magnetic clamp.
[0007] In some embodiments, each bracket of each of the opening and closing actuation devices is further provided with an eccentric wheel and a shaft, the drive unit drives the eccentric wheel to rotate, the eccentric wheel is eccentrically connected to a connecting rod, the connecting rod is connected to the shaft, and the shaft is connected to the base.
[0008] In some embodiments, each of the pushers includes a push rod and a roller, one end of the push rod being connected to the base, and the other end of the push rod extending from the base and having the roller disposed thereon, and each of the pushers being pushed by the roller.
[0009] In some embodiments, the push rod includes a rod portion and a fork portion, one end of the rod portion is connected to the base, the fork portion is connected to the other end of the rod portion, and the roller is rotatably connected to the fork portion and protrudes from the fork portion.
[0010] In some embodiments, each of the brackets has two guide slots, and the base of each of the push structures is connected to two rods, each rod being slidably extended into each of the guide slots.
[0011] Compared with the prior art, the present invention has the following advantages: by dividing the clamping of one of the magnetic clamps into two stages, the first stage controls the magnetic clamp to be in a half-open and half-clamped state, and the second stage controls the magnetic clamp to start clamping the substrate from the half-open and half-clamped state. In this way, the clamping kinetic energy of the magnetic clamp can be reduced, thereby achieving the effect of avoiding cracking or crushing the substrate. Attached Figure Description
[0012] Figure 1 This is a side view of the wet processing equipment (without a suspended carrier) of this utility model.
[0013] Figure 2 This is a front-view cross-sectional schematic diagram of the wet process equipment (without a suspended carrier) of this utility model.
[0014] Figure 3 This utility model is based on Figure 1 A side view of the push structure and support of an opening and closing actuator.
[0015] Figure 4 This utility model is based on Figure 3 A top-down view.
[0016] Figure 5 This utility model is based on Figure 3 A schematic diagram from one perspective.
[0017] Figure 6 This is a front view schematic diagram of the carrier in the wet process equipment of this utility model (with the substrate already clamped).
[0018] Figure 7 This is a side cross-sectional view of one of the magnetic clamps in the wet process processing equipment (with a suspended carrier) of this utility model.
[0019] Figure 8 This utility model is based on Figure 7 A partially enlarged schematic diagram of the opening and closing actuator located at the top before it is pushed.
[0020] Figure 9 This utility model is based on Figure 7 A partially enlarged schematic diagram of the opening and closing actuator located at the bottom before it is pushed.
[0021] Figure 10 This utility model is based on Figure 7 A cross-sectional view when viewed from the front.
[0022] Figure 11 This utility model is based on Figure 7 A top-down view of the opening and closing actuator located at the top of the device before it is pushed.
[0023] Figure 12 This is a side view of the opening and closing actuation device located at the top of the present invention after it has been pushed.
[0024] Figure 13 This is a side view of the opening and closing actuation device located at the lower part of the present invention after being pushed.
[0025] Figure 14 This utility model is based on Figure 7 A top-down view of the opening and closing actuator located at the top of the device after it is pushed.
[0026] Figure 15 This is a side view of the opening and closing actuator located at the top of the present invention after it has been retracted.
[0027] Figure 16 This is a side view of the opening and closing actuator located at the lower part of the present invention after it has been retracted.
[0028] Figure 17 This utility model is based on Figure 7 A top view of the opening and closing actuator located at the top of the image after it has been retracted.
[0029] Figure 18 This is a side cross-sectional view of the opening and closing actuation device located at the top of this utility model before it is pushed against another magnetic clamp.
[0030] Figure 19 This utility model is based on Figure 18 A side view sectional diagram after the push.
[0031] Figure 20 This utility model is based on Figure 19 A side view sectional diagram after the section has been retracted.
[0032] Explanation of markings in the diagram:
[0033] 100: Pushing structure; 1: Base; 11: Rod; 2a: First pusher; 2b: Second pusher; 2c: Third pusher; 21: Push rod; 211: Rod section; 213: Fork section; 22: Roller; 300: Bracket; 35: Guide groove; 41: Eccentric wheel; 42: Connecting rod; 43: Shaft; 800: Carrier; 8: Frame; 81: Hanger; 9: Magnetic clamp; 91: Clamping plate; 911: Magnetic clamping end; 912: Other end; A1: Opening and closing actuation device; A2: Opening and closing actuation device; L1: Upper crossbar; L2: Lower crossbar; M: Drive unit; P1: Closed position; P2: Fully open position; S: Base plate; T: Conveying unit. Detailed Implementation
[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.
[0035] This utility model provides a wet process processing equipment and its magnetic clamp opening and closing actuation device, such as... Figure 7 As shown, the wet processing equipment of this invention mainly suspends a carrier 800 holding a substrate S on a conveying unit T, and performs wet processing on the substrate S held on the carrier 800 during the conveying process of the conveying unit T. The substrate S held by this invention can be any substrate, and is particularly suitable for glass substrates that can be used for semiconductor packaging.
[0036] like Figures 1 to 9 As shown, the wet processing equipment of this utility model includes: two opening and closing actuation devices A1 and A2 and the aforementioned carrier 800.
[0037] The carrier 800 includes a frame 8, an upper crossbar L1, and a lower crossbar L2, which are spaced apart and connected to each other within the frame 8. The frame 8 is equipped with a hanger 81, and the carrier 800 is suspended from the conveying unit T and conveyed by the conveying unit T using the hanger 81. At least one pair of magnetic clamps 9 are provided on both the upper crossbar L1 and the lower crossbar L2. The number of magnetic clamps 9 on the upper or lower crossbars L1 and L2 can be one pair or several pairs, as shown in the figure. For simplicity, the following explanation will focus on one pair. For ease of explanation, the two magnetic clamps 9 in a pair will be referred to below as a first magnetic clamp 9 (unclamped state) and a second magnetic clamp 9 (clamped state). The magnetic clamp 9 has a magnetic clamping end 911 and a other end 912 that are opposite to each other. The magnetic clamping end 911 is equipped with a magnetic element (such as a magnet, the element symbol is not shown). Therefore, when the magnetic clamping ends 911 are brought close to each other to an appropriate distance, they can be magnetically attracted to each other by the magnetic element, thereby completing the clamping.
[0038] Two opening and closing actuators A1 and A2, for example, can be an upper opening and closing actuator A1 and a lower opening and closing actuator A2 (but this utility model is not limited to this), which are respectively configured corresponding to the upper crossbar L1 and the lower crossbar L2 and their structures are reversed. Each opening and closing actuator A1 (or A2) includes a pair of supports 300 spaced apart from each other and a pair of push structures 100 respectively disposed on the pair of supports 300. Specifically, the two opening and closing actuators A1 and A2 are respectively mounted in a wet process processing equipment.
[0039] Two pairs of brackets 300 are located on opposite sides of the carrier 800 and each is provided with a drive unit M. Two pairs of push structures 100 are slidably disposed on the pair of brackets 300, and each drive unit M is disposed on each bracket 300, so that each drive unit M can drive each push structure 100 to move closer to or further away from each other.
[0040] In detail, each pushing structure 100 includes a base 1 and several pushing members protruding from the base 1. The base 1 of each pushing structure 100 is slidably disposed on each bracket 300 and driven to slide by each driving unit M. Each pushing structure 100 has several pushing members, including a first pushing member 2a, a second pushing member 2b, and a third pushing member 2c. The first pushing member 2a corresponds to the magnetic clamping end 911 of the first magnetic clamp 9, the second pushing member 2b corresponds to the other end 912 of the first magnetic clamp 9, and the third pushing member 2c corresponds to the other end 912 of the second magnetic clamp 9. The two bases 1 have opposing surfaces (not labeled) facing each other, and the pushing members (first pushing member 2a, second pushing member 2b, and third pushing member 2c) are all provided and protrude from the opposing surfaces of the bases 1.
[0041] In this way, such as Figures 7 to 14 As shown, when the two drive units M of each actuation device A1 and A2 drive the two push structures 100 to move relative to each other, the bases 1 of the two push structures 100 will move together with the aforementioned push members (first push member 2a, second push member 2b, and third push member 2c) closer to each other. After the movement, the first push member 2a of the two push structures 100 of the actuation device A1 (A2) will push the magnetic clamping end 911 of the first magnetic clamp 9 to clamp and align, allowing the other end 912 to open from a closed position P1 to a fully open position P2 (see...). Figure 8 and Figure 15 As for the second pusher 2b of the two push structures 100 of the opening and closing actuation device A1 (A2), it blocks the other end 912 between the closed position P1 and the fully open position P2 of the first magnetic clamp 9. This allows the magnetic clamping end 911 and the other end 912 of the first magnetic clamp 9 to... Figure 12 As shown, both are kept in a half-open, half-clamped state. In this embodiment, it means that the first magnetic clamp 9 on the upper crossbar L1 and the first magnetic clamp 9 on the lower crossbar L2 are kept in a half-open, half-clamped state after being pushed. The word "fully open" in the fully open position P2 means that the magnetic clamping end 911 or the other end 912 is fully opened to the end.
[0042] Next, as Figures 15 to 17 As shown, when the two drive units M of each opening and closing actuation device A1 and A2 respectively drive the two push structures 100 to retract from the first magnetic clamp 9 on the upper crossbar L1 and the first magnetic clamp 9 on the lower crossbar L2, since the second push member 2b, which was originally blocking the movement path of the other end 912 from the closed position P1 to the fully open position P2, has retracted and no longer blocks, the magnetic clamping end 911 can close and clamp the substrate S by using the magnetic attraction of the aforementioned magnetic elements to each other, while the other end 912 is opened to the fully open position P2.
[0043] It should be noted that the action of the second magnetic clamp 9 is performed simultaneously with the action of the first magnetic clamp 9, because the plurality of pushers (first pusher 2a, second pusher 2b and third pusher 2c) are all located on the base 1.
[0044] Therefore, as Figures 18 to 20 As shown, when each actuating device A1, A2 ( Figures 18 to 20When the two drive units M of the upper opening and closing actuation device A1 drive the two push structures 100 to move relative to each other, the bases 1 of the two push structures 100 will move closer to each other along with the third push member 2c. After the movement, the third push member 2c of the two push structures 100 of the opening and closing actuation device A1 will push the other end 912 of the second magnetic clamp 9 to the second magnetic clamp 9 from the clamping state. Figure 18 ) becomes unclamped state ( Figure 19 Next, after the two drive units M respectively drive the two push structures 100 to retract from the second magnetic clamp 9 on the upper crossbar L1, the second magnetic clamp 9 remains in an unclamped state. Figure 20 ).
[0045] In this way, the present invention can use the push structure 100 to simultaneously control the first and second magnetic clamps 9 to alternately clamp and release the substrate S. Moreover, since the first magnetic clamp 9 adopts a two-stage clamping method, that is, in the first stage, the magnetic clamping end 911 of the first magnetic clamp 9 is in a half-clamped state (that is, the entire first magnetic clamp 9 is in a half-open and half-clamped state). The first magnetic clamp 9 can only use the magnetic clamping end 911 to clamp the substrate S by magnetic attraction in the second stage. In other words, the movement distance of the magnetic clamping end 911 from the half-clamped state in the first stage to the fully clamped state in the second stage is necessarily shorter than the movement distance of the magnetic clamp from the fully open state to the fully clamped state without the opening and closing actuation devices A1 and A2 of the present invention (the movement distance can be reduced by half). Therefore, the clamping kinetic energy of the magnetic clamping end 911 can be weakened accordingly, thereby achieving the effect of avoiding cracking or breaking the substrate S (e.g., glass substrate). Furthermore, since the second magnetic clamp 9 is only pushed from the clamping state to the unclamped state, and the other end 912 that is pushed does not have a magnetic suction element, even if the other end 912 goes directly from fully open to fully clamped, its clamping kinetic energy will be weaker than that of the magnetic clamping end 911, and it will not crack or break the substrate S (e.g., glass substrate). In other words, for the other end 912 of the second magnetic clamp 9, there is no need for two-stage clamping, that is, only the third pushing member 2c is needed, and the fourth pushing member not shown in the figure is not needed. The opening and closing actuation devices A1 and A2 in this utility model can simultaneously perform the action of alternately clamping and releasing the substrate S of any pair of magnetic clamps 9.
[0046] Accordingly, Figure 6 and Figure 10 As shown, by allowing the conveying unit T to move the carrier 800 a short distance laterally relative to the opening and closing actuators A1 and A2, the opening and closing actuators A1 (A2) can perform the action of alternately clamping and releasing the substrate S in relation to another pair of magnetic clamps 9.
[0047] This allows the liquid sprayed during the wet process to be sprayed onto the entire substrate S without leaving any unsprayed areas, through alternating clamping and releasing.
[0048] It should be noted that, as Figures 3 to 5 As shown, each pusher (any of 2a, 2b, and 2c) includes a push rod 21 and a roller 22 (which may be a soft rubber wheel, but is not limited thereto). One end of the push rod 21 is connected to the aforementioned opposite surface of the base 1, and the other end of the push rod 21 extends from the opposite surface of the base 1 and is provided with a roller 22 at the extended end, so that each pusher (2a, 2b, 2c) can use the roller 22 to push any of the aforementioned magnetic clamps 9 to open or close. In detail, the push rod 21 includes a rod portion 211 and a fork portion 213. One end of the rod portion 211 is connected to the opposite surface of the base 1, and the fork portion 213 is connected to the other end of the rod portion 211. The roller 22 is rotatably connected to the fork portion 213 and protrudes from the fork portion 213.
[0049] Furthermore, in order to enable the push structure 100 to slide smoothly relative to the bracket 300, each bracket 300 is provided with two guide grooves 35 that are spaced apart from each other, and the base 1 of each push structure 100 is connected to two rods 11, and each rod 11 can slide into each guide groove 35, so that each rod 11 can be guided by each guide groove 35 to slide in a preset direction.
[0050] In addition, each bracket 300 is equipped with an eccentric wheel 41 and a shaft 43. The aforementioned drive unit M drives the eccentric wheel 41 to rotate, the shaft 43 is connected to the base 1, and the eccentric wheel 41 is eccentrically connected to a connecting rod 42, which is connected to the shaft 43. Accordingly, the drive unit M can drive the eccentric wheel 41 to rotate, and the connecting rod 42 can drive the base 1 to move relative to the bracket 300 through the shaft 43.
[0051] It should also be noted that, as Figure 8As shown, any of the aforementioned magnetic clamps 9 includes two clamps 91 that are rotatably connected to each other. Each clamp 91 is a straight and flat plate, so the outer sides of the two clamps 91 are both straight and flat. As for the inner sides (adjacent sides) of the two clamps 91, each has a semicircular body (not indicated) protruding from it. The two semicircular bodies are rotatably overlapped and connected to each other. In order to keep any magnetic clamp 9 in the half-open and half-closed state of the first stage, the first pusher 2a and the second pusher 2b of each push structure 100 (located on two opposite sides of any magnetic clamp 9) can protrude from the base 1 to the same degree, or one pusher can protrude slightly while the other pusher is slightly retracted and the degree of protrusion and retraction is equal (of course, the degree of protrusion and retraction of the two pushers can be different depending on the actual situation of the magnetic clamp). This utility model does not limit this, as long as the magnetic clamp 9 can be kept in the half-open and half-closed state in the first stage.
[0052] In summary, the wet processing equipment and its magnetic clamping actuation device of this utility model can indeed achieve the expected purpose and effect, and can solve the shortcomings of the prior art.
[0053] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present utility model, and the protection scope of the present utility model is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present utility model, or reasonable combinations of solutions from various embodiments, are all within the protection scope of the present utility model.
Claims
1. A magnetic clamp opening and closing actuation device, for being driven by a pair of drive units to control the opening and closing of a pair of magnetic clamps, each of the magnetic clamps having a magnetic clamping end and a third end, characterized in that, The opening / closing actuation device includes: A pair of brackets, each equipped with one of the aforementioned drive units; and A pair of pushing structures, each of the pushing structures comprising a base and a plurality of pushing members protruding from the base, the base of each of the pushing structures being slidably disposed on each of the brackets and driven by each of the driving units to move relative to each other, the plurality of pushing members of each of the pushing structures comprising a first pushing member, a second pushing member and a third pushing member, the first pushing member and the second pushing member respectively corresponding to the magnetic clamping end and the other end of one of the magnetic clamps, and the third pushing member corresponding to the other end of the other magnetic clamp; In this configuration, each drive unit drives each base to move relative to each bracket along with several pushers. The first pusher of each pusher structure pushes the magnetic clamping end of one of the magnetic clamps to clamp and close, allowing the other end to open from a closed position to a fully open position. The second pusher of each pusher structure blocks the other end of one of the magnetic clamps between the closed position and the fully open position. The third pusher of each pusher structure pushes the other end of another magnetic clamp.
2. The opening and closing actuation device for the magnetic clamp as described in claim 1, characterized in that, Each of the aforementioned pushers includes a push rod and a roller. One end of the push rod is connected to the base, and the other end of the push rod extends from the base and is provided with the roller. Each of the pushers is pushed by the roller.
3. The opening and closing actuation device for the magnetic clamp as described in claim 2, characterized in that, The push rod includes a rod portion and a fork portion. One end of the rod portion is connected to the base, and the fork portion is connected to the other end of the rod portion. The roller is rotatably connected to the fork portion and protrudes from the fork portion.
4. The opening and closing actuation device for the magnetic clamp as described in claim 1, characterized in that, Each of the brackets has two guide slots, and the base of each of the push structures is connected to two rods, each rod being slidably extended into each of the guide slots.
5. A wet processing equipment, characterized in that, include: A carrier includes a frame, an upper crossbar and a lower crossbar, the upper crossbar and the lower crossbar spanning within the frame and each provided with at least one pair of magnetic clamps, each of the magnetic clamps having a magnetic clamping end and an other end; as well as Two opening and closing actuation devices are respectively configured corresponding to the upper crossbar and the lower crossbar, and each opening and closing actuation device includes: A pair of brackets, each equipped with a drive unit; and A pair of pushing structures, each of the pushing structures comprising a base and a plurality of pushing members protruding from the base, the base of each of the pushing structures being slidably disposed on each of the brackets and driven by each of the driving units to move relative to each other, the plurality of pushing members of each of the pushing structures comprising a first pushing member, a second pushing member and a third pushing member, the first pushing member and the second pushing member respectively corresponding to the magnetic clamping end and the other end of one of the magnetic clamps, and the third pushing member corresponding to the other end of the other magnetic clamp; In this configuration, each drive unit drives each base to move relative to each bracket along with several pushers. The first pusher of each pusher structure pushes the magnetic clamping end of one of the magnetic clamps to clamp and close, allowing the other end to open from a closed position to a fully open position. The second pusher of each pusher structure blocks the other end of one of the magnetic clamps between the closed position and the fully open position. The third pusher of each pusher structure pushes the other end of another magnetic clamp.
6. The wet processing equipment as described in claim 5, characterized in that, Each bracket of each of the aforementioned opening and closing actuation devices is further provided with an eccentric wheel and a shaft. The drive unit drives the eccentric wheel to rotate. The eccentric wheel is eccentrically connected to a connecting rod. The connecting rod is connected to the shaft. The shaft is connected to the base.
7. The wet processing equipment as described in claim 5, characterized in that, Each of the pushers includes a push rod and a roller. One end of the push rod is connected to the base, and the other end of the push rod extends from the base and is provided with the roller. Each of the pushers uses the roller to push the magnetic clamp to open and close.
8. The wet processing equipment as described in claim 7, characterized in that, The push rod includes a rod portion and a fork portion. One end of the rod portion is connected to the base, and the fork portion is connected to the other end of the rod portion. The roller is rotatably connected to the fork portion and protrudes from the fork portion.
9. The wet processing equipment as described in claim 5, characterized in that, Each of the brackets has two guide slots, and the base of each of the push structures is connected to two rods, each rod being slidably extended into each of the guide slots.