A rapid positioning device suitable for circuit board processing and a drilling machine workbench
By pre-setting threaded holes in the bakelite board and using a fast positioning device with fasteners and supports, combined with infrared positioning on the drilling machine's worktable, the problem of traditional bakelite board pin positioning methods being unable to adapt to circuit boards of different specifications has been solved, achieving rapid positioning and efficient production of circuit boards.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SICHUAN HUIDING ELECTRONICS CO LTD
- Filing Date
- 2025-07-28
- Publication Date
- 2026-07-21
AI Technical Summary
Traditional bakelite board pin positioning method is difficult to adapt to circuit boards of different sizes, resulting in unstable positioning, low production efficiency and poor flexibility.
By pre-setting several first threaded holes in the bakelite board and fixing it to the circuit board through fasteners and supports, combined with the infrared positioner of the drilling machine's worktable, the circuit board can be quickly positioned and flexibly switched.
It can adapt to different circuit boards without re-drilling, improving production efficiency and flexibility, avoiding the "duplicate hole" phenomenon, and reducing replacement costs and time.
Smart Images
Figure CN224538420U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of circuit board processing technology, and in particular to a rapid positioning device and a drilling machine worktable suitable for circuit board processing. Background Technology
[0002] During PCB manufacturing, drilling is required. This process necessitates precisely positioning and fixing the PCB to be processed onto the drilling machine's worktable. Currently, the commonly used method is the bakelite board pin positioning method. The process is roughly as follows: First, the operator drills pin holes on the bakelite board that match the specific PCB model. Then, a pin with a diameter slightly larger than the hole diameter is manually driven into the hole. Next, the PCB to be processed is placed on the bakelite board with the pins inserted, aligning the pre-drilled positioning holes on the PCB with the pins. Then, the operator applies tape around the edges of the PCB to ensure a tight fit and fixation between the PCB and the bakelite board. After completing the positioning and fixing process, parameters are input into the machine's computer, and the drilling program is started.
[0003] The above method is difficult to efficiently adapt to circuit boards of different sizes and specifications. Specifically, when processing PCBs of different sizes or models, the positions of their positioning holes will inevitably change. Therefore, it is necessary to re-drill the PIN holes on the original bakelite board to match the positioning holes of the replaced circuit board. However, the bakelite board usually already has the PIN holes of the old model. The newly drilled PIN holes are very likely to intersect with the old PIN holes, resulting in a "duplicate hole" phenomenon. The "duplicate hole" may weaken the structure of the bakelite board, causing the new pins to be unable to be firmly fixed and the positioning to fail. To solve this problem, a lot of time is usually required to check, avoid or deal with the duplicate holes, or even replace the bakelite board.
[0004] Therefore, the traditional bakelite board pin positioning method restricts production efficiency and flexibility in the production of circuit boards with multiple varieties or frequent model changes, because it requires repeated modification of PIN holes for circuit boards of different sizes and faces the risk of "duplicate holes". Utility Model Content
[0005] The present invention aims to provide a rapid positioning device and a drilling machine workbench suitable for circuit board processing, so as to solve the problem that the traditional bakelite board pin positioning method is difficult to adapt to circuit boards of different specifications and sizes.
[0006] The technical solution adopted by this utility model to solve its technical problem is: to provide a rapid positioning device suitable for circuit board processing, which can match circuit boards of various specifications, comprising: A bakelite board, wherein a plurality of first threaded holes are evenly arranged on the surface of the bakelite board within a predetermined area; At least four fasteners are provided, each fastener having a second threaded hole and a first groove; the second threaded hole is fixedly connected to the positioning hole of the circuit board by a first screw; the fastener is fixed to the surface of the bakelite board by means of a second screw passing through the first groove and connecting to the first threaded hole at a suitable position on the surface of the bakelite board. At least two support members are provided, each support member having a second slot; the support member is positioned below the edge of the circuit board to support the circuit board; the support member is fixed to the surface of the bakelite board by means of a third screw passing through the second slot and connecting to a first threaded hole at a suitable position on the surface of the bakelite board.
[0007] Furthermore, the first threaded holes are arranged in a rectangular array within the predetermined area.
[0008] Furthermore, the width direction of the bakelite board is defined as the X-axis, and the length direction is defined as the Y-axis; In the rectangular array arrangement, the center-to-center distance between two adjacent first threaded holes in the X-axis direction is L1, and the center-to-center distance between two adjacent second threaded holes in the Y-axis direction is L2; wherein the ratio of L1 to L2 is between 0.8 and 1.25.
[0009] Furthermore, the value of L1 is between 20mm and 50mm, and the value of L2 is also between 20mm and 50mm.
[0010] Furthermore, the fastener is a strip-shaped structure with a boss at one end, the first threaded hole is formed on the surface of the boss, and the first strip groove is formed in the non-boob area.
[0011] Furthermore, the length of the first strip is L3, where L3 ≥ 2L1 and L3 ≥ 2L2.
[0012] Furthermore, a recessed groove is formed on the surface of the support member, and the second strip groove is formed in the recessed groove.
[0013] Furthermore, the length of the second strip is L4, where L4 ≥ 2L1 and L4 ≥ 2L2.
[0014] Furthermore, the first threaded hole is not provided in the middle region of the bakelite board within a suitable length and width range, based on the minimum size of the circuit board to be processed.
[0015] In one embodiment, a plurality of the first threaded holes are respectively formed in each independent column, and each column is embedded in and bonded to a pre-set hole on the surface of the bakelite board.
[0016] This utility model also provides a drilling machine workbench adapted to the above-mentioned rapid positioning device. The surface of the workbench is provided with a rectangular groove, and a limiting block is provided around each of the four sides of the rectangular groove. A sloping guide surface is formed on the inner side of the top of the limiting block. The workbench is also equipped with a limiting block, which can be fixedly connected to the threaded holes at the four corners of the rectangular sink by a fourth screw, so as to press and fix the four corners of the bakelite board placed in the rectangular sink.
[0017] This invention solves the problem that the traditional bakelite board pin positioning method is difficult to adapt to circuit boards of different specifications and sizes, and has the following advantages: (1) No need to re-drill holes: When replacing circuit boards of different specifications using traditional methods, it is necessary to re-drill PIN holes on the bakelite board, which easily leads to "duplicate holes" and makes it impossible to effectively position the circuit board; however, this patent has several first threaded holes pre-set on the bakelite board. When replacing circuit boards of different specifications, the position of the fastener can be directly adjusted and fixedly connected to the appropriate first threaded hole, avoiding repeated drilling of PIN holes. (2) Quick switching: When changing to different specifications of circuit boards, only the fixing parts and support parts need to be disassembled and moved, saving the steps of re-drilling, avoiding holes or even replacing the bakelite board, which can significantly shorten the changeover time and improve production efficiency and flexibility. Attached Figure Description
[0018] Figure 1 This is a diagram illustrating the use of the rapid positioning device in Embodiment 1; Figure 2 Will Figure 1 A diagram showing the circuit board after it has been removed. Figure 3 yes Figure 1 Independent view of the central fastener; Figure 4 yes Figure 1 Independent view of the central support component; Figure 5 This refers to the process of fixing the bakelite board from Example 1 onto the worktable of the drilling machine. Figure 1 ; Figure 6 This refers to the process of fixing the bakelite board from Example 1 onto the worktable of the drilling machine. Figure 2 ; Figure 7 This refers to the process of fixing the bakelite board from Example 1 onto the worktable of the drilling machine. Figure 3 ; Figure 8 This is a diagram illustrating the process of fixing the circuit board onto the bakelite board. Figure 9 This is an independent view of the bakelite board in the rapid positioning device of Embodiment 2. Detailed Implementation
[0019] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.
[0020] Example 1: See Figures 1 to 4 This embodiment provides a quick positioning device 100 suitable for circuit board processing, which can match circuit boards 200 of various specifications. The quick positioning device 100 includes a bakelite board 110, a fixing member 120 and at least two support members 130.
[0021] The surface of the bakelite board 110 has a plurality of first threaded holes 11a evenly arranged in a predetermined area.
[0022] There are at least four fasteners 120. See also Figure 3 The fastener 120 is provided with a second threaded hole 12a and a first strip groove 12b. See also Figure 1 and Figure 2 The second threaded hole 12a is fixedly connected to the positioning hole 210 of the circuit board 200 by the first screw 141. The fixing member 120 is fixed to the surface of the bakelite board 110 by means of the second screw 142 passing through the first strip groove 12b and connecting to the first threaded hole 11a at a suitable position on the surface of the bakelite board 110.
[0023] There are at least two support members 130. See also Figure 4 The support member 130 is provided with a second strip groove 13a. (See also...) Figure 1 and Figure 2 The support member 130 is disposed below the edge of the circuit board 200 to provide support for the circuit board 200. The support member 130 is fixed to the surface of the bakelite board 110 by means of a third screw 143 passing through the second strip groove 13a and connecting to the first threaded hole 11a at a suitable position on the surface of the bakelite board 110.
[0024] Typically, positioning holes 210 are provided at the corners of the circuit board 200 (see...). Figure 2When positioning the circuit board 200, the corners of the circuit board 200 can be fixedly connected to the positioning member 120 by connecting the first screw 141 mentioned above. Then, the fixing member 120 can be fixed to the surface of the bakelite board 110 by connecting the second screw 142 mentioned above. That is to say, after the positioning holes 210 at the four corners of the circuit board 200 are fixedly connected to the four fixing members 120 respectively, and the four fixing members 120 are fixedly connected to the first threaded holes 11a at appropriate positions on the surface of the bakelite board 110, the circuit board 200 will be fixed, and then the drilling operation can begin. After drilling is completed, the four first screws 141 are removed, and the circuit board 200 can be removed. See Figure 2 When processing the next circuit board 200, align the four corners of the next circuit board 200 with the second threaded holes 12a of the four fixing members 120, and then tighten the first screws 141 to fix the next circuit board 200. Then, begin drilling. When processing circuit boards 200 of other sizes, first remove the fixing members 120 fixed to the bakelite board 110. Then, perform the same operation: simply connect the positioning holes 210 at the four corners of the new circuit board 200 to the four fixing members 120, and then connect the four fixing members 120 to the first threaded holes 11a at appropriate positions on the surface of the bakelite board 110 to fix the replaced circuit board 200. Compared with the traditional bakelite board pin positioning method, when the size of the circuit board 200 changes, there is no need to drill new pin holes. The pre-drilled first threaded holes 11a on the bakelite board 110 can lock the fixing members 120 after the position change, thereby fixing the circuit board 200 connected to the fixing members 120. The operation is convenient and quick.
[0025] The aforementioned support member 130 serves to support the edge of the circuit board 200, preventing the circuit board 200 from collapsing downwards in the middle area due to lack of support during drilling, which would affect the drilling quality.
[0026] In a preferred embodiment, the first threaded holes 11a are arranged in a rectangular array within the predetermined area.
[0027] The aforementioned predetermined area can be any area on the surface of the bakelite board 110 excluding the edge areas, or it can be any other area on the surface of the bakelite board 110 excluding the edge areas and the central area (see...). Figure 2In the second scenario, the central region of the bakelite board 110 does not require the first threaded hole to be set within a suitable length and width range based on the minimum size of the circuit board 200 to be processed. In other words, among all the different sizes of circuit boards 200 to be processed, the smallest circuit board 200 has a lower limit on its length and width. Since the circuit board 200 is usually fixed in the central region of the bakelite board 110, regardless of which size of circuit board 200 is used, a certain area in the central region of the bakelite board 110 will always be covered by the circuit board 200. The fastener 120 and the support 130 can never be fixed in this area. Therefore, it is not necessary to open the first threaded hole 11a in this area, thereby saving the time and cost of opening these first threaded holes 11a.
[0028] In addition, the edge area of the surface of the bakelite board 110 usually needs to cooperate with the limiting device to fix the bakelite board 110 on the worktable of the drilling machine. Therefore, the edge area of the surface of the bakelite board 110 usually does not need to have the first threaded hole 11a.
[0029] In this embodiment, the width direction of the bakelite board 110 is defined as the X-axis, and the length direction as the Y-axis. In the rectangular array arrangement, the center-to-center distance between two adjacent first threaded holes 11a in the X-axis direction is L1, and the center-to-center distance between two adjacent second threaded holes 12a in the Y-axis direction is L2. The ratio of L1 to L2 is between 0.8 and 1.25.
[0030] Preferably, the value of L1 is between 20mm and 50mm, and the value of L2 is also between 20mm and 50mm.
[0031] Preferably, the length of the first strip groove 12b is L3, where L3 ≥ 2L1 and L3 ≥ 2L2. This length ensures that the first strip groove 12b has a large coverage area. When the second threaded hole 12a is connected to the positioning hole 210 of the circuit board 200 (the first screw 141 only connects the two and is not fully tightened), the position can be adjusted by rotating the fixing member 120 to ensure that the first strip groove 12b can be aligned with at least one of the first threaded holes 11a on the bakelite board 110 so that the two can be fixedly connected by the second screw 142.
[0032] Preferably, the length of the second strip groove 13a is L4, where L4 ≥ 2L1 and L4 ≥ 2L2. This length ensures that the second strip groove 13a has a large coverage area, so that when fixing the support member 130, the second strip groove 13a can be aligned with at least the two first threaded holes 11a on the bakelite board 110 in the X-axis or Y-axis direction, ensuring that the support member 130 can be fixed to the bakelite board 110 by two third screws 143.
[0033] In a preferred embodiment, see Figure 3 The fastener 120 has a strip-shaped structure with a boss 121 at one end. The first threaded hole 11a is formed on the surface of the boss 121, and the first strip groove 12b is formed in the non-boob area. With this structure, the fastener 120 is only thick at the first threaded hole 11a, and relatively thin at other locations, thus reducing the material used in the fastener 120 and lowering the cost.
[0034] In a preferred embodiment, see Figure 4 The support member 130 has a recessed groove 13b on its surface, and the second strip groove 13a is formed in the recessed groove 13b. In this structure, after the third screw 143 fixes the support member 130 to the bakelite board 110, its head can be hidden in the recessed groove 13b, avoiding the head of the third screw 143 from protruding and affecting the supporting function of the support member 130 on the circuit board 200.
[0035] The usage method of this embodiment is as follows: First, place the bakelite board 110 on the worktable 300 of the drilling machine; wherein, see Figure 5 The workbench 300 has a rectangular recess 310 on its surface. Each of the four sides of the rectangular recess 310 has a limiting block 320, and the inner side of the top of each limiting block 320 forms a sloping guide surface 321. When placing the bakelite board 110, the four limiting blocks 320 serve a positioning function, ensuring the bakelite board 110 is accurately placed in the middle area of the rectangular recess 310. The sloping guide surface 321 provides guidance; if there is a misalignment, it guides the bakelite board 110 during its descent, ensuring it is accurately placed within the area defined by the four limiting blocks 320. After the bakelite board 110 is placed, refer to... Figure 6 Limiting blocks 340 are installed on the four corners of the bakelite board 110. The limiting blocks 340 are fixedly connected to the threaded holes 330 at the four corners of the rectangular recess 310 by the fourth screw 350. After the limiting blocks 340 are installed, they can press and fix the four corners of the bakelite board 110, so that the bakelite board 110 is stably fixed in the rectangular recess 310. See Figure 7 ; Next, prepare the circuit board 200 to be processed, and then connect the four corners of the circuit board 200 to the fixing parts 120 respectively; when connecting, pass the first screw 141 through the positioning hole of the circuit board 200, and then screw it into the second threaded hole 12a of the fixing part 120, but do not tighten the first screw 141 completely. An infrared positioner (not shown in the figure) is pre-installed above the drilling machine worktable 300. This infrared positioner can project two infrared rays in the X-axis direction onto the surface of the worktable 300. Figure 8The two horizontal dashed lines) and the two Y-axis infrared lines ( Figure 8 The four infrared beams projected by the four infrared beams are symmetrical about the horizontal axis of the worktable 300 and about the vertical axis of the worktable 300. The position of each infrared beam is adjustable. These four beams guide the placement of the four edges of the circuit board 200. Before placing the circuit board 200, parameters are pre-set according to its length and width to ensure that the area enclosed by the four infrared beams matches the length and width of the circuit board 200 (and it should be noted that the center point of the area enclosed by the four infrared beams coincides with the center point of the worktable 300). Then, along the four infrared lines, multiple support members 130 are fixed to the surface of the bakelite board 110; during fixing, if the width or length dimension of the circuit board 200 is large, two or more support members 130 can be fixed on one edge line. Figure 8 In this circuit board 200, due to its long side being quite long, two support members 130 are installed under each long side, and only one support member 130 is installed under each wide side, for a total of six support members 130. Once fixed, the support members 130 will provide support below the edges of the circuit board 200, preventing the central area from collapsing during drilling due to the large span and lack of support, thus affecting drilling quality. After the support members 130 are fixed, the circuit board 200 can be placed within the area enclosed by the four infrared rays. During placement, ensure that the four edges of the circuit board 200 are aligned with the four infrared rays (see...). Figure 8 ); Subsequently, the four fasteners 120 connected to the corners of the circuit board 200 need to be fixed to the bakelite board 100; during fixing, since the first screw 141 is not fully tightened, the appropriate first threaded hole 11a can be found by rotating the fasteners 120. Figure 8 The dotted lines in the diagram represent the rotatable range of the fastener 120, ensuring that each first slot 12b is aligned with at least one of the first threaded holes 11a, see [reference]. Figure 8 (Due to the appropriate positioning in the diagram, each slot 12b aligns perfectly with the two first threaded holes 11a); then, screw in the second screw 142 to fix the four fasteners 120 onto the bakelite board 100. The effect after fixing can be seen in the diagram. Figure 1 ; Thus, the circuit board 200 is stably fixed on the worktable 300 of the drilling machine. Furthermore, since the center point of the circuit board 200 coincides with the center point of the worktable 300, the drill bit can directly move according to the coordinates of the worktable 300 to make holes in the circuit board 200 during subsequent drilling, which is convenient and quick.
[0036] When processing circuit board 200, after processing each circuit board 200, the four first screws 141 are removed with a power tool to remove the circuit board 200. Then, the next circuit board 200 is installed, and the four first screws 141 are tightened with a power tool to fix the four corners of the next circuit board 200 to the four fasteners 120 respectively. Then, the drilling machine can be started to start drilling operations on the next circuit board 200. Compared with the previous bakelite board pin positioning method, the circuit board 200 is fixed by screws, and there is no need to stick tape around it for fixation, thus saving the purchase cost of tape.
[0037] If the dimensions of the circuit board 200 to be processed change later, follow these steps: First, remove each fixing part 120 and support part 130 from the bakelite board 110. Then, connect each fixing part 120 to the positioning hole 210 of the modified circuit board 200 using the first screw 141. As before, do not fully tighten the first screw 141. Next, adjust the infrared locator so that the positions of the four infrared lines match the length and width dimensions of the modified circuit board 200, i.e., the area enclosed by the four infrared lines is consistent with the length and width dimensions of the modified circuit board 200. Then, as before, fix multiple support parts 130 to the surface of the bakelite board 110 along the four infrared lines. Then, place the modified circuit board 200 within the area enclosed by the four infrared lines, aligning the four edges of the circuit board 200 with the four infrared lines. Finally, rotate each fixing part 120 to find the appropriate first threaded hole 11a. Each first slot 12b is aligned with at least one first threaded hole 11a. Finally, the second screw 142 is screwed in to fix the four fasteners 120 onto the bakelite board 100. Then, the drilling machine can be started to begin drilling the circuit board 200. After each circuit board 200 is processed, as before, the first screw 141 is removed, the next circuit board 200 is replaced, and the first screw 141 is installed to begin drilling the next circuit board 200. Compared with the previous bakelite board pin positioning method, when the size of the circuit board 200 changes, there is no need to drill new PIN holes. The fasteners 120 whose positions have changed can be locked by using the pre-drilled first threaded holes 11a on the bakelite board 110, thereby fixing the circuit board 200 connected to the fasteners 120. The operation is convenient and quick, saving the tedious steps of drilling new PIN holes and avoiding the phenomenon of "overlapping holes" that may occur when drilling new PIN holes intersect with old PIN holes.
[0038] Example 2: The main differences between this embodiment and Embodiment 1 are as follows: See Figure 9In this embodiment, a plurality of first threaded holes 11a are respectively opened in each independent column 111, and each column 111 is embedded and bonded to each hole 11b pre-set on the surface of the bakelite board 110.
[0039] The column 111 is made of rubber or plastic, and its outer diameter is equal to or slightly larger than the inner diameter of the hole 11b. In operation, a first threaded hole 11a is first made on the column 111 using a drilling device. Then, glue is applied to the outer surface of the column 111, and it is then inserted into the pre-set hole 11b on the surface of the bakelite board 110. After the glue dries, the column 111 will be firmly bonded to the hole 11b.
[0040] The advantage of this design is that the column 111 is detachable. When the thread of the first threaded hole 11a is damaged, the column 111 can be pried out with the appropriate tool and then a new column 111 can be installed. This ensures that the bakelite board 110 can continue to be used and avoids the situation where the thread is damaged and the bakelite board 110 needs to be replaced, thus saving replacement costs.
[0041] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A rapid positioning device suitable for circuit board processing, capable of accommodating circuit boards of various specifications, characterized in that, include: A bakelite board (110) has a plurality of first threaded holes (11a) evenly arranged on its surface within a predetermined area. At least four fasteners (120) are provided, each fastener (120) having a second threaded hole (12a) and a first slot (12b); the second threaded hole (12a) is fixedly connected to the positioning hole of the circuit board by a first screw (141); the fastener (120) is fixed to the surface of the bakelite board (110) by means of a second screw (142) passing through the first slot (12b) and connecting to the first threaded hole (11a) at a suitable position on the surface of the bakelite board (110); At least two support members (130) are provided with a second slot (13a); the support members (130) are provided below the edge of the circuit board to support the circuit board; the support members (130) are fixed to the surface of the bakelite board (110) by means of a third screw (143) passing through the second slot (13a) and connecting to a first threaded hole (11a) at a suitable position on the surface of the bakelite board (110).
2. The rapid positioning device for circuit board processing according to claim 1, characterized in that, The first threaded holes (11a) are arranged in a rectangular array within the predetermined area.
3. A rapid positioning device suitable for circuit board processing according to claim 2, characterized in that, The width direction of the bakelite board (110) is defined as the X-axis, and the length direction is defined as the Y-axis; In the rectangular array arrangement, the center-to-center distance between two adjacent first threaded holes (11a) in the X-axis direction is L1, and the center-to-center distance between two adjacent second threaded holes (12a) in the Y-axis direction is L2; wherein, the ratio of L1 to L2 is between 0.8 and 1.
25.
4. A rapid positioning device suitable for circuit board processing according to claim 3, characterized in that, The value of L1 is between 20mm and 50mm, and the value of L2 is also between 20mm and 50mm.
5. A rapid positioning device suitable for circuit board processing according to claim 4, characterized in that, The fastener (120) is a strip structure with a boss (121) formed at one end. The first threaded hole (11a) is opened on the surface of the boss (121), and the first strip groove (12b) is opened in the non-boob area.
6. A rapid positioning device suitable for circuit board processing according to claim 5, characterized in that, The length of the first strip (12b) is L3, where L3 ≥ 2L1 and L3 ≥ 2L2.
7. A rapid positioning device suitable for circuit board processing according to claim 6, characterized in that, The surface of the support member (130) is provided with a recessed groove (13b), and the second strip groove (13a) is formed in the recessed groove (13b).
8. A rapid positioning device suitable for circuit board processing according to claim 7, characterized in that, The length of the second strip groove (13a) is L4, where L4 ≥ 2L1 and L4 ≥ 2L2.
9. A rapid positioning device suitable for circuit board processing according to any one of claims 1 to 8, characterized in that, The first threaded hole is not provided in the middle region of the bakelite board (110) within a suitable length and width range according to the minimum size of the circuit board to be processed.
10. A drilling machine worktable adapted to the rapid positioning device of claim 1, characterized in that, The surface of the workbench (300) is provided with a rectangular sink (310), and a limiting block (320) is provided around each of the four sides of the rectangular sink (310). A sloping guide surface (321) is formed on the inner side of the top of the limiting block (320). The workbench (300) is also equipped with a limiting block (340), which can be fixedly connected to the threaded holes (330) at the four corners of the rectangular sink (310) by a fourth screw (350) to press and fix the four corners of the bakelite board (110) placed in the rectangular sink (310).