A hole-opening mold for ceramic sheets

Abstract

The invention discloses a ceramic sheet hole drilling mold, which relates to the technical field of ceramic sheet hole drilling, and comprises an upper mold and a lower mold, wherein a plurality of hydraulic rods are arranged between the upper mold and the lower mold, a connecting strip is arranged at the bottom of the lower mold, a numerical control moving platform is arranged at the bottom of the connecting strip, two clamping rings for clamping and fixing the ceramic sheet are arranged above the lower mold, a connecting cylinder is arranged inside the upper mold, an air outlet is arranged above the connecting cylinder, a connector is arranged inside the bottom end of the connecting cylinder, a drill bit for drilling holes in the ceramic sheet is arranged inside the connector, a plurality of vertical grooves are arranged inside the drill bit, an expansion body for covering the vertical grooves is arranged on the inner wall of the drill bit, a filling unit for inflating the expansion body is arranged inside the connecting cylinder, in this mold, the two processes of drilling and deburring are carried out simultaneously, which reduces the processing time and labor cost, and greatly improves the production efficiency of the ceramic sheet.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic sheet hole punching, in particular to a ceramic sheet hole punching mould. Background Art

[0002] In my country's ceramic industry, especially in the production of sanitary ceramic products, a large number of ceramic pieces are needed. In order to ensure the quality and aesthetics of sanitary products, various opening molds are needed for molding.

[0003] There are many types of hole punching dies on the market, but there are still some problems in the process of punching holes in ceramic sheets. For example, when punching holes, the contact between the rotating cutter head and the ceramic sheet will generate a large amount of waste, some of which will directly fall into the bottom of the die through the through hole, and some small waste may adhere to the inner wall of the hole of the ceramic sheet, forming large and small waste burrs, which will cause difficulties in the subsequent assembly of the ceramic sheet; the common solution is to add another process specifically for deburring the ceramic hole. This treatment method increases the cost and prolongs the processing time, which is not conducive to improving the production efficiency of the ceramic sheet.

[0004] To this end, the present invention provides a hole-forming mold for a ceramic sheet. Summary of the invention

[0005] The purpose of the present invention is to provide a ceramic sheet hole-making die to solve the problems raised in the above background technology. To achieve the above purpose, the present invention provides the following technical solutions: a ceramic sheet hole-making die, comprising an upper die and a lower die, a plurality of hydraulic rods are arranged between the upper die and the lower die, a connecting strip is arranged at the bottom of the lower die, a numerical control moving platform is arranged at the bottom of the connecting strip, and two clamping rings are arranged above the lower die to clamp and fix the ceramic sheet;

[0006] A connecting tube is provided inside the upper mold, an air outlet is provided above the connecting tube, a connector is provided inside the bottom end of the connecting tube, a drill bit for drilling holes in the ceramic sheet is provided inside the connector, a plurality of vertical grooves are provided inside the drill bit, an expansion body for covering the vertical grooves is provided on the inner wall of the drill bit, a filling unit for inflating the inside of the expansion body is provided inside the connecting tube, and when the expansion body is in the maximum expansion state, the outer wall of the expansion body and the outer wall of the drill bit overlap each other;

[0007] A liquid injection tube is provided on one side of the drill bit, and an absorption tube is provided on the other side of the drill bit. The absorption tube is located inside the upper mold, and an air suction unit is provided above the upper mold. The air suction unit cooperates with the filling unit to drive the absorption tube to absorb the smoke generated by the drilling.

[0008] The expansion body includes a vertical portion and a protruding portion, and the expansibility of the protruding portion is greater than that of the vertical portion.

[0009] Preferably, the filling unit includes a screw located inside the connector, a movable plate is provided on the outer wall of the screw, a groove body is provided on the inner wall of the movable plate, the groove body is located on the inner wall of the connecting tube and is fixedly connected thereto, gas is filled between the bottom surface of the movable plate and the bottom surface of the connecting tube, a motor is provided at the end of the screw, and the motor is fixedly connected to the upper mold through a fixing frame.

[0010] Preferably, the air intake unit comprises a transfer pipe on the outer wall of the absorption tube, the end of the transfer pipe is connected to the connecting tube, a one-way valve is provided on the inner wall of the transfer pipe, the passing direction of the one-way valve is from the absorption tube to the connecting tube, an air pipe is provided on one side of the transfer pipe, a liquid storage box is provided at the end of the air pipe, and the liquid storage box is used to dissolve the absorbed flue gas.

[0011] Preferably, a material storage box is provided on one side of the absorption tube, and the position of the material storage box is located above the inclined surface area of ​​the absorption tube.

[0012] Preferably, an air pipe 2 is provided at the end of the air outlet, and the shape of the air pipe 2 is C-shaped. The end of the air pipe 2 is located inside the lower mold, and a flow groove is provided on one side of the end of the air pipe 2. The overall shape of the flow groove is a broken line. A collecting box is provided at the end of the flow groove, and the vertical center line of the vertical area of ​​the flow groove coincides with the vertical center line of the drill bit.

[0013] Preferably, a one-way valve 2 is provided inside the air pipe 2, and the flow direction of the one-way valve 2 is from the connecting tube to the inside of the flow groove.

[0014] Preferably, the portion of the air pipe 2 located inside the lower mold is parallel to the inclined area of ​​the flow groove.

[0015] Preferably, the central cross section of the absorption tube coincides with the central cross section of the injection tube, and a diffusion box is provided at the end of the absorption tube, and the overall shape of the diffusion box is arc-shaped.

[0016] The present invention has at least the following beneficial effects:

[0017] 1. In the present invention, when the drilling is completed, the motor reverses and the drill bit is lifted along with the hydraulic rod, the movable plate moves downward, the air inside the drill bit will be squeezed, so that the outer wall of the expansion body and the outer wall of the drill bit overlap with each other, the expansion body itself will rotate along with the screw and be driven up by the hydraulic rod, this process can make the expansion body rotate and clean the burrs on the inner wall of the borehole, so as to ensure good drilling quality; as the drill bit rises, until the expansion body is completely separated from the surface of the ceramic sheet, the protrusion of the expansion body in this state will continue to expand, so that the bottom of the protrusion extends out of the drill bit and contacts the surface of the ceramic sheet, and the central surface area of ​​the ceramic sheet is wiped; through the filling unit, the burrs on the inner wall and surface edge of the borehole are completely removed, so that the two processes of drilling and deburring are carried out simultaneously, which reduces the processing time and labor cost, and greatly improves the production efficiency of the ceramic sheet.

[0018] 2. In the present invention, the downwardly displaced moving sheet will also drive the transfer tube to generate attraction, and then drive the end of the absorption tube to absorb the surrounding area of ​​the drill bit. On the one hand, the harmful smoke generated by the drilling can be sucked into the liquid storage box on one side of the transfer tube to ensure the personal safety of the staff; on the other hand, the waste flushed by the infusion tube can also be absorbed and collected in the storage box. Due to the presence of the one-way valve, when the moving sheet rises, the smoke and waste will not be discharged from the absorption tube again, ensuring a clean working environment above the mold, which is conducive to improving the processing efficiency of the ceramic sheet.

[0019] 3. In the present invention, the portion of the ceramic sheet itself that is discharged by drilling can directly fall into the flow trough. Under the continuous liquid flushing of the injection pipe, the cutting fluid will enter the flow trough at the same time as the waste material, and push the waste material into the collection box. As the movable sheet rises, the gas will be discharged from the air outlet to the interior of the air pipe 2. Since the inclined surface area of ​​the air pipe 2 is parallel to the inclined surface area of ​​the flow trough, the gas discharged from the two ends of the air pipe will help promote the flow of liquid and waste material in the flow trough, thereby ensuring that the mold has a good waste collection rate and providing the ceramic sheet with a clean processing environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 It is a schematic diagram of the structure of the present invention from another angle;

[0022] Figure 3 This is a cross-sectional view of the structure of each component from the upper mold to the lower mold of the present invention;

[0023] Figure 4 For the present invention Figure 3 A magnified view of the structure of the middle A area;

[0024] Figure 5 For the present invention Figure 3 A magnified view of the structure of the middle B region;

[0025] Figure 6 This is a cross-sectional view of the structure of each component from the upper mold to the lower mold of the present invention;

[0026] Figure 7 For the present invention Figure 6 A magnified view of the structure of the middle C region;

[0027] Figure 8 For the present invention Figure 6 A magnified view of the structure in region D.

[0028] In the figure: 1-upper mold; 2-lower mold; 3-hydraulic rod; 4-connecting strip; 5-CNC moving table; 6-clamping ring; 7-connecting cylinder; 8-air outlet; 9-connector; 10-drill bit; 11-vertical groove; 12-expansion body; 1201-vertical part; 1202-protrusion; 13-filling unit; 1301-screw; 1302-moving sheet; 1303-tank body; 1304-motor; 14-liquid injection pipe; 15-absorption pipe; 16-air suction unit; 1601-transfer pipe; 1602-one-way valve one; 1603-trachea one; 1604-liquid storage box; 17-material storage box; 18-trachea two; 19-flow tank; 20-collection box; 21-one-way valve two; 22-diffusion box. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figure 1-8 The present invention provides a technical solution: a ceramic sheet opening mold, comprising:

[0031] Embodiment 1,

[0032] An upper mold 1 and a lower mold 2 are provided with multiple hydraulic rods 3 between the upper mold 1 and the lower mold 2. There are four hydraulic rods 3 in total. The two ends of each hydraulic rod 3 are fixedly connected to the upper mold 1 and the lower mold 2 respectively. A connecting strip 4 is provided at the bottom of the lower mold 2 and is fixedly connected thereto. A CNC moving table 5 is provided at the bottom of the connecting strip 4. Two clamping rings 6 for clamping and fixing the ceramic sheet are provided above the lower mold 2. The clamping rings 6 slide relative to the surface of the lower mold 2. The CNC moving table 5 is controlled by a program of an external device to drive the lower mold 2 and the upper mold 1 to move to any position on the same plane. At the same time, the hydraulic rods 3 are also automatically controlled by an external device to perform up and down reciprocating extrusion motion. The above is the prior art, so it will not be repeated here.

[0033] In this scheme, a connecting tube 7 is provided inside the upper mold 1 and is fixedly connected thereto, an air outlet 8 is provided above the connecting tube 7, a connector 9 is provided inside the bottom end of the connecting tube 7, the connector 9 is rotatably connected to the connecting tube 7, a drill bit 10 for drilling holes in the ceramic sheet is provided inside the connector 9, the drill bit 10 is fixedly connected to the connector 9, a plurality of vertical grooves 11 are provided inside the drill bit 10, and an expansion body 12 for covering the vertical grooves 11 is provided on the inner wall of the drill bit 10, and the vertical grooves 11 and the expansion body 12 each have two, and they correspond one to one, and the expansion body 12 The outer wall of the expansion body 12 is fixedly connected to the inner wall of the drill bit 10, and a filling unit 13 for inflating the inside of the expansion body 12 is provided inside the connecting tube 7. When the expansion body 12 is in the maximum expansion state, the outer wall of the expansion body 12 and the outer wall of the drill bit 10 overlap with each other. After the drilling is completed and the drill bit 10 is lifted, the outer wall of the expansion body 12 and the inner wall of the hole of the ceramic sheet are rubbed by the filling and expansion effect of the expansion body 12, thereby driving the burrs adhering to the inner wall to fall off, thereby greatly improving the opening quality of the ceramic sheet;

[0034] An injection tube 14 is provided on one side of the drill bit 10. The injection tube is located inside the upper mold 1 and is fixedly connected thereto. The injection tube can continuously provide cutting fluid to the drilling site to reduce the contact temperature between the drill bit 10 and the ceramic sheet. An absorption tube 15 is provided on the other side of the drill bit 10. The central cross section of the absorption tube 15 coincides with the central cross section of the injection tube 14. A diffusion box 22 is provided at the end of the absorption tube 15 and is fixedly connected thereto. The overall shape of the diffusion box 22 is arc-shaped. The absorption tube 15 and the injection tube 14 are arranged at positions opposite to each other, so that the flushing direction of the injection tube 14 on the waste generated by the drilling is consistent with the absorption direction of the absorption tube 15. At the same time, the arc shape of the diffusion box 22 covers most of the area around the drill bit 10, and cooperates with the flushing direction of the injection tube 14, further improving the absorption rate of the absorption tube 15 on the ceramic waste, ensuring a relatively clean environment during the continuous drilling process.

[0035] The absorption tube 15 is located inside the upper mold 1 and fixedly connected thereto. An air suction unit 16 is provided above the upper mold 1. The air suction unit 16 cooperates with the filling unit 13 to drive the absorption tube 15 to absorb the smoke generated by drilling, thereby effectively preventing the harmful smoke produced by drilling from having adverse effects on the workers.

[0036] The filling unit 13 includes a screw 1301 located inside the connector 9, the end of the screw 1301 is fixedly connected to the connector 9, the outer wall of the screw 1301 is provided with a moving sheet 1302 and is threadedly connected thereto, the inner wall of the moving sheet 1302 is provided with a groove 1303, the moving sheet 1302 slides freely along the outer wall of the groove 1303 in the up and down directions, the groove 1303 is located on the inner wall of the connecting tube 7 and is fixedly connected thereto, the bottom surface of the moving sheet 1302 and the bottom surface of the connecting tube 7 are filled with gas, the end of the screw 1301 is provided with a motor 1304, the screw 1301 is connected to the rotating shaft of the motor 1304 through a coupling, the motor 1304 is fixedly connected to the upper mold 1 through a fixing frame, and the expansion body 12 includes a vertical portion 1 201 and the protrusion 1202, the expansibility of the protrusion 1202 is greater than that of the vertical portion 1201. During the drilling process, the motor 1304 will drive the screw 1301 and the drill bit 10 to rotate, and the movable sheet 1302 will rise in the connecting tube 7. When the drilling is completed, the motor 1304 will reverse and the hydraulic rod 3 will also drive the drill bit 10 to rise. At this time, the movable sheet 1302 moves downward, so that the gas is squeezed inside the drill bit 10, so that the outer wall of the expansion body 12 expands until it resists the inner wall of the drill hole. The special flexible material of the expansion body 12 will rotate with the drill bit 10, which is more conducive to removing the burrs on the inner wall of the hole, shortening the processing time and improving the production efficiency of the ceramic sheet;

[0037] The air intake unit 16 includes a transfer pipe 1601 on the outer wall of the absorption tube 15, one end of the transfer pipe 1601 is fixedly connected to the absorption tube 15, the end of the transfer pipe 1601 is connected to the connecting tube 7, a one-way valve 1602 is provided on the inner wall of the transfer pipe 1601 and is fixedly connected thereto, the passing direction of the one-way valve 1602 is from the absorption tube 15 to the connecting tube 7, an air pipe 1603 is provided on one side of the transfer pipe 1601 and is connected thereto, a liquid storage box 1604 is provided on the end of the air pipe 1603 and is connected thereto, the bottom of the liquid storage box 1604 is fixedly connected to the upper mold 1, the liquid storage box 1604 contains a chemical solution that can dissolve the absorbed flue gas, a material storage box 17 is provided on one side of the absorption tube 15 and is fixedly connected thereto, the position of the material storage box 17 is located above the inclined area along the absorption tube 15, the material storage box 17 can effectively collect small waste generated by drilling, and provide a tidy environment for drilling.

[0038] When in use, when the upper mold 1 is driven down by the hydraulic rod 3 and the ceramic sheet is drilled normally, the rotation of the motor 1304 will drive the movable sheet 1302 to rise. At this time, the gas inside the connecting tube 7 and the drill bit 10 is relatively dispersed, and the expansion body 12 will not expand. When the drilling is completed, the motor 1304 reverses and the drill bit 10 is lifted with the hydraulic rod 3, and the movable sheet 1302 in the connecting tube 7 will move downward. At this time, the air inside the drill bit 10 will be squeezed, thereby driving the expansion body 12 to expand, so that the outer wall of the expansion body 12 and the outer wall of the drill bit 10 overlap with each other. The surface of the expansion body 12 has a special flexible material, and it will rotate with the screw 1301 and be driven up by the hydraulic rod 3. This process allows the expansion body 12 to clean the burrs on the inner wall of the drill hole without dead angles, thereby ensuring good drilling quality.

[0039] It is worth noting that as the drill bit 10 gradually rises, until the expansion body 12 is completely separated from the surface of the ceramic sheet, the vertical portion 1201 of the expansion body 12 in this state still overlaps with the outer wall of the drill bit 10, and the protrusion 1202 of the expansion body 12 will continue to expand, so that the bottom of the protrusion 1202 extends out of the drill bit 10 and contacts the surface of the ceramic sheet, and the central surface area of ​​the ceramic sheet is wiped during the continuous rotation of the drill bit 10; the burrs on the inner wall and surface edge of the drill hole are removed in all directions through the filling unit 13, so that the two processes of drilling and deburring are carried out at the same time, which reduces the processing time and labor cost, and greatly improves the production efficiency of the ceramic sheet;

[0040] At the same time, the downwardly displaced moving sheet 1302 will also drive the transfer tube 1601 to generate attraction, and then drive the end of the absorption tube 15 to absorb the surrounding area of ​​the drill bit 10. On the one hand, the harmful smoke generated by the drilling can be sucked into the liquid storage box 1604 on one side of the transfer tube 1601, and absorbed and decomposed by the solution inside it, thereby ensuring the personal safety of the staff; on the other hand, the waste flushed by the infusion tube can also be absorbed and collected in the storage box 17. Due to the presence of the one-way valve 1602, when the moving sheet 1302 rises, the gas is blocked by the one-way valve 1602, and the smoke and waste will not be discharged from the absorption tube 15 again, thereby ensuring a clean working environment above the mold, which is conducive to improving the processing efficiency of the ceramic sheet.

[0041] According to the above embodiment, embodiment 2,

[0042] An air pipe 18 is provided at the end of the air outlet 8 and is connected with the air pipe 18. The air pipe 18 is C-shaped. The end of the air pipe 18 is located inside the lower mold 2 and is fixedly connected thereto. A flow groove 19 is provided on one side of the end of the air pipe 18. The flow groove 19 is located inside the lower mold 2. The overall shape of the flow groove 19 is in a broken line shape. A collecting box 20 is provided at the end of the flow groove 19. One side of the collecting box 20 is fixedly connected to the lower mold 2. The vertical center line of the vertical area of ​​the flow groove 19 coincides with the vertical center line of the drill bit 10. A one-way valve 21 is provided inside the air pipe 18 and is fixedly connected thereto. The flow direction of the one-way valve 21 is from the connecting tube 7 to the inside of the flow groove 19. The one-way valve 21 can prevent the gas inside the air pipe 18 from flowing back into the inside of the connecting tube 7, thereby reducing the attraction of the absorption tube 15. The part of the air pipe 18 located inside the lower mold 2 is parallel to the inclined area of ​​the flow groove 19.

[0043] The part of the ceramic sheet itself that is discharged by drilling can directly fall into the flow groove 19. At the same time, due to the continuous liquid flushing of the injection pipe 14, the cutting fluid will enter the flow groove 19 at the same time as the waste, and push the waste into the collection box 20 under the influence of the water flow; on the other hand, as the movable sheet 1302 rises, the gas will be discharged from the air outlet 8 to the inside of the air pipe 18. Since the inclined area along the air pipe 18 is parallel to the inclined area of ​​the flow groove 19, the gas discharged from the end of the air pipe 18 will help promote the flow of liquid and waste inside the flow groove 19, thereby ensuring that this mold has a good waste collection rate and that the ceramic sheet has a clean processing environment.

[0044] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0045] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A ceramic sheet hole-perforating die, comprising an upper die (1) and a lower die (2), a plurality of hydraulic rods (3) being arranged between the upper die (1) and the lower die (2), a connecting strip (4) being arranged at the bottom of the lower die (2), a numerical control moving platform (5) being arranged at the bottom of the connecting strip (4), and two clamping rings (6) for clamping and fixing the ceramic sheet being arranged above the lower die (2); Features: A connecting tube (7) is provided inside the upper mold (1), an air outlet (8) is provided above the connecting tube (7), a connector (9) is provided inside the bottom end of the connecting tube (7), a drill bit (10) for drilling holes in the ceramic sheet is provided inside the connector (9), a plurality of vertical grooves (11) are provided inside the drill bit (10), an expansion body (12) for covering the vertical grooves (11) is provided on the inner wall of the drill bit (10), a filling unit (13) for inflating the inside of the expansion body (12) is provided inside the connecting tube (7), and when the expansion body (12) is in the maximum expanded state, the expansion body (12) The outer wall of the connecting tube (7) and the outer wall of the drill bit (10) overlap with each other, the filling unit (13) comprises a screw (1301) located inside the connector (9), the outer wall of the screw (1301) is provided with a moving sheet (1302), the inner wall of the moving sheet (1302) is provided with a groove body (1303), the groove body (1303) is located on the inner wall of the connecting tube (7) and is fixedly connected thereto, the bottom surface of the moving sheet (1302) and the bottom surface of the connecting tube (7) are filled with gas, and the end of the screw (1301) is provided with a motor (1304), and the motor (1304) is fixedly connected to the upper mold (1) via a fixing frame; A liquid injection tube (14) is provided on one side of the drill bit (10), and an absorption tube (15) is provided on the other side of the drill bit (10); the absorption tube (15) is located inside the upper mold (1), and an air suction unit (16) is provided above the upper mold (1); the air suction unit (16) cooperates with the filling unit (13) to drive the absorption tube (15) to absorb smoke generated by drilling; The expansion body (12) comprises a vertical portion (1201) and a protruding portion (1202), and the expansibility of the protruding portion (1202) is greater than that of the vertical portion (1201).

2. The ceramic sheet hole forming mold according to claim 1, characterized in that: The air intake unit (16) comprises a transfer pipe (1601) on the outer wall of the absorption pipe (15), the end of the transfer pipe (1601) being connected to the connecting tube (7), the inner wall of the transfer pipe (1601) being provided with a one-way valve (1602), the passage direction of the one-way valve (1602) being from the absorption pipe (15) to the connecting tube (7), an air pipe (1603) being provided on one side of the transfer pipe (1601), the end of the air pipe (1603) being provided with a liquid storage box (1604), the liquid inside the liquid storage box (1604) being used to dissolve the absorbed smoke.

3. The ceramic sheet hole forming mold according to claim 2, characterized in that: A material storage box (17) is provided on one side of the absorption tube (15), and the position of the material storage box (17) is located above the line along the inclined surface area of ​​the absorption tube (15).

4. The ceramic sheet hole forming mold according to claim 1, characterized in that: A second air pipe (18) is provided at the end of the air outlet (8), the shape of the second air pipe (18) is C-shaped, the end of the second air pipe (18) is located inside the lower mold (2), a flow groove (19) is provided on one side of the end of the second air pipe (18), the overall shape of the flow groove (19) is a broken line, a collection box (20) is provided at the end of the flow groove (19), and the vertical center line of the vertical area of ​​the flow groove (19) coincides with the vertical center line of the drill bit (10).

5. The ceramic sheet hole forming mold according to claim 4, characterized in that: A second one-way valve (21) is provided inside the second air pipe (18), and the flow direction of the second one-way valve (21) is from the connecting tube (7) to the inside of the flow groove (19).

6. The ceramic sheet hole punching mold according to claim 4, characterized in that: The portion of the second air pipe (18) located inside the lower mold (2) is parallel to the inclined surface area of ​​the flow groove (19).

7. The ceramic sheet hole forming mold according to claim 2, characterized in that: The central cross section of the absorption tube (15) overlaps with the central cross section of the injection tube (14); a diffusion box (22) is provided at the end of the absorption tube (15); and the overall shape of the diffusion box (22) is arc-shaped.

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