Cutting device for fluorescent glass production

Abstract

According to the cutting device for fluorescent glass production, a cutting table and a knocking table are arranged, the edge of the cutting table is fixedly connected with an X-direction guide rail, the X-direction guide rail is divided into a first X-direction guide rail and a second X-direction guide rail through a partition plate, and a first Y-direction guide rail is slidably arranged in the width direction of the cutting table; a second Y-direction guide rail is slidably arranged in the width direction of the knocking table, a cutting head is slidably connected along the first Y-direction guide rail, a Z-direction guide rail is slidably connected along the second Y-direction guide rail, a pressing mechanism used for pressing glass is arranged on the side, away from the ground, of the knocking table, and a vibration mechanism is fixedly connected to the side, away from the ground, of the pressing mechanism. The vibration mechanism is slidably connected to the Z-direction guide rail, and the cutting table is rotationally connected with a feeding mechanism used for glass feeding. By the adoption of the technical scheme, the cutting precision can be conveniently adjusted during glass feeding; the cutting requirements of fluorescent glass of different sizes are met; and the probability of edge breakage in the knocking process after glass cutting is effectively reduced.

Description

Technical Field

[0001] The invention relates to the field of fluorescent glass processing equipment, and in particular to a cutting device for producing fluorescent glass. Background Art

[0002] Fluorescent glass is widely used because it produces green, yellow, and red light through the stimulation of blue light, and finally mixes to obtain white light. In the cutting process, glass cutters, sand-added water cutting, or laser cutting are usually used. After cutting, the cut part needs to be knocked out. In this process, if the force of knocking is unbalanced, it is easy to cause edge collapse, which affects the subsequent polishing.

[0003] The Chinese invention patent with application number 201910834892.8 discloses a photoelectric glass cutting machine, including a PLC controller, a frame, a workbench, a tool holder and a blowing and suction device. The workbench is installed on the frame, and Y-guide rails are correspondingly provided on both sides of the workbench. The Y-guide rails are installed with Y-direction sliders. The Y-direction sliders are connected by a slide plate and a mounting plate. The slide plate is arranged below the workbench, and the mounting plate is arranged above the workbench. The frame is installed with a belt transmission mechanism, and the belt transmission mechanism is installed on the slide plate through a Y-direction lead screw and a lead screw nut. The mounting plate is provided with an X-direction guide rail, and the X-direction slider is installed on the X-direction guide rail. There are two tool holders, and the tool holder is installed on the X-direction slider through a linear motor. The blowing and suction device is installed on the frame and is located below the workbench. The blowing and suction device is used to fix the glass on the workbench. The belt transmission mechanism, the linear motor, and the blowing and suction device are all connected to the PLC controller.

[0004] The above solution controls the tool holder through the X-axis slider and the Y-axis guide rail to control the cutting accuracy. However, when the cutting part is knocked out after cutting, the edge is easily broken due to uneven force, which affects the glass cutting accuracy. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies in the above-mentioned technology and to propose a cutting device for fluorescent glass production, which aims to solve the problem of edge collapse when the cutting part is knocked during the cutting process, thereby affecting the cutting accuracy.

[0006] The present invention provides a cutting device for producing fluorescent glass, comprising a cutting table and a knocking table, wherein the cutting table is fixedly connected to the knocking table, an X-guide rail is fixedly connected to the edge of the cutting table, and the middle part of the X-guide rail is divided into a first X-guide rail and a second X-guide rail by a partition plate, a first Y-guide rail is slidably arranged along the width direction of the cutting table, a second Y-guide rail is slidably arranged along the width direction of the knocking table, a cutting head is slidably connected along the first Y-guide rail, a Z-guide rail is slidably connected along the second Y-guide rail, a pressing mechanism for pressing glass is arranged on the side of the knocking table away from the ground, a vibration mechanism is fixedly connected to the side of the pressing mechanism away from the ground, the vibration mechanism is slidably connected to the Z-guide rail, and a feeding mechanism for feeding glass is rotatably connected to the cutting table. The knocking table is fixedly connected with an elastic tabletop. The glass is cut by setting a cutting table, and the cut glass is separated by knocking on the knocking table. The first X-guide rail and the first Y-guide rail enable the cutting head to adjust the cutting size. The second Y-guide rail and the second Z-guide rail can move and lift the pressing mechanism to adapt to cut glass of different sizes. The vibration mechanism separates the cut glass by vibration and pressing.

[0007] Preferably, a first X-direction slider is slidably connected along the first X-direction guide rail, the side of the first X-direction slider away from the ground is fixedly connected to the end of the first Y-direction guide rail, the first Y-direction slider is slidably connected to the first Y-direction guide rail, the first Y-direction slider is fixedly connected to the cutting head, the second X-direction slider is slidably connected to the second X-direction guide rail, the side of the second X-direction slider away from the ground is fixedly connected to the end of the second Y-direction guide rail, the Z-guide rail slides on the second Y-guide rail, and the Z-direction slider is slidably connected to the Z-guide rail.

[0008] Preferably, the pressing mechanism includes a protective cover, a center gear, a rack, a pressing rod, a pressing head and a first motor. The rack is meshed with the teeth of the center gear. The four racks are arranged in a cross shape and are staggered up and down. The rack is parallel to the table top of the knocking table. The pressing rod is vertically and fixedly connected to the end of each rack and is located in the extension direction of the rack as the center gear rotates. The pressing head is detachably sleeved on the end of the pressing rod close to the knocking table. The pressing head and the pressing rod have an interference fit. The center of the center gear away from the ground is fixedly connected to the output end of the first motor. The first motor is fixedly connected to the inner wall of the protective cover, and the rack passes through the protective cover.

[0009] Preferably, the vibration mechanism includes a telescopic rod, a spring, a fixed plate, a fixed block, a second motor and a shaped wheel, the spring is sleeved in the telescopic rod, one end of the telescopic rod is fixedly connected to the protective cover, the other end of the telescopic rod is fixedly connected to the fixed plate, one end of the fixed block is fixedly connected to an end of the fixed plate close to the ground, the other end of the fixed block is fixedly connected to the second motor, the output end of the second motor is fixedly connected to the center of the shaped wheel, the shaped wheel is movably abutted against the protective cover, and the side of the fixed plate away from the ground is fixedly connected to the Z-direction slider.

[0010] Preferably, the cutting table is rotatably connected to a plurality of parallel conveyor belts arranged at intervals, and the loading mechanism comprises a rotating shaft, a folding tube, a plug-in tube and a suction cup. The rotating shaft is rotatably connected to the cutting table along the width direction of the cutting table. The folding tube is a tube with multiple bending nodes, one end of the folding tube is fixedly connected to the rotating shaft, and the tube body of the folding tube away from the rotating shaft is fixedly and spaced apart with a plurality of plug-in tubes, the suction cup is sleeved on the plug-in tube, and the folding tube is located in the gap between the conveyor belts.

[0011] Preferably, the protective cover is fixedly connected to the limiting rod, the end of the limiting rod away from the protective cover is fixedly connected to the limiting ring, and the rack is sleeved in the limiting ring. The inner wall of the limiting ring close to the teeth of the rack is arc-shaped.

[0012] Compared with the prior art, it has the following beneficial effects:

[0013] The present invention provides a cutting device for fluorescent glass production, which is provided with a cutting table and a knocking table, wherein an X-guide rail is fixedly connected to the edge of the cutting table, the X-guide rail is divided into a first X-guide rail and a second X-guide rail by a partition plate, a first Y-guide rail is slidably provided along the width direction of the cutting table, a second Y-guide rail is slidably provided along the width direction of the knocking table, a cutting head is slidably connected along the first Y-guide rail, a Z-guide rail is slidably connected along the second Y-guide rail, a pressing mechanism for pressing glass is provided on the side of the knocking table away from the ground, a vibration mechanism is fixedly connected to the side of the pressing mechanism away from the ground, the vibration mechanism is slidably connected to the Z-guide rail, and a feeding mechanism for glass feeding is rotatably connected to the cutting table. The above technical scheme is adopted to facilitate the adjustment of cutting accuracy when feeding glass; to adapt to the cutting requirements of fluorescent glass of different sizes; and to effectively reduce the probability of edge collapse during the knocking process after glass cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only preferred embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 A schematic diagram of a cutting device for producing fluorescent glass according to the present invention;

[0016] Figure 2 A side view of a cutting device for producing fluorescent glass according to the present invention;

[0017] Figure 3 is a schematic diagram of the extrusion mechanism of the present invention;

[0018] Figure 4 It is an internal schematic diagram of the extrusion mechanism of the present invention;

[0019] Figure 5 It is a partial enlarged schematic diagram of A of the present invention;

[0020] Figure 6 It is a schematic diagram of the telescopic rod and spring of the present invention;

[0021] Figure 7 It is a partial enlarged schematic diagram of B of the present invention.

[0022] In the figure, the cutting table 1; the X-direction guide rail 11; the first X-direction guide rail 111; the first X-direction slider 112; the first Y-direction guide rail 12; the first Y-direction slider 121; the cutting head 13; the conveyor belt 14; the partition plate 15; the knocking table 2; the second X-direction guide rail 21; the second Y-direction guide rail 22; the Z-direction guide rail 23; the Z-direction slider 24; the pressing mechanism 3; the protective cover 31; the central gear 32; the rack 33; the pressing rod 34; the pressing head 35; the first motor 36; the limiting rod 37; the limiting ring 38; the vibration mechanism 4; the telescopic rod 41; the spring 42; the fixing plate 43; the fixing block 44; the second motor 45; the special-shaped wheel 46; the feeding mechanism 5; the rotating shaft 51; the folding tube 52; the plug-in tube 53; the suction cup 54. DETAILED DESCRIPTION

[0023] In order to make it easier to understand the structure of the present invention and the functional features and advantages that can be achieved, the preferred embodiments of the present invention are described in detail with reference to the drawings as follows:

[0024] Example:

[0025] like Figures 1 to 7As shown, the present invention provides a cutting device for fluorescent glass production, including a cutting table 1 and a knocking table 2, wherein the cutting table 1 is fixedly connected to the knocking table 2, and after the knocking table 2 extends to the cutting table 1, the cutting table 1 is rotatably connected to a plurality of parallel conveyor belts 14 arranged with gaps. The conveyor belt 14 is driven by the rotation of the upper shaft of the cutting table 1, and the gaps of the conveyor belt 14 are filled with planes except for the feeding mechanism 5, so that the plane is flat. After the cutting is completed, the transmission belt conveys the fluorescent glass to the knocking table 2 for knocking. An X-direction guide rail 11 is fixedly connected to the edge of the cutting table 1, and the middle part of the X-direction guide rail 11 is divided into a first X-direction guide rail 111 and a second X-direction guide rail 21 by a partition plate 15, and the partition plate 15 is located at the gap between the knocking table 2 and the cutting table 1. A first Y-direction guide rail 12 is slidably arranged along the width direction of the cutting table 1, a second Y-direction guide rail 22 is slidably arranged along the width direction of the knocking table 2, a cutting head 13 is slidably connected along the first Y-direction guide rail 12, and a Z-direction guide rail 23 is slidably connected along the second Y-direction guide rail 22. A first X-direction slider 112 is slidably connected along the first X-direction guide rail 111, a side of the first X-direction slider 112 away from the ground is fixedly connected to the end of the first Y-direction guide rail 12, a first Y-direction slider 121 is slidably connected to the first Y-direction guide rail 12, the first Y-direction slider 121 is fixedly connected to the cutting head 13, a second X-direction slider is slidably connected to the second X-direction guide rail 21, a side of the second X-direction slider away from the ground is fixedly connected to the end of the second Y-direction guide rail 22, a Z-direction guide rail 23 slides on the second Y-direction guide rail 22, and a Z-direction slider 24 is slidably connected to the Z-direction guide rail 23. The first X-direction guide rail 111 and the first Y-direction guide rail 12 enable the cutting head 13 to adjust the size of the cut.

[0026] A pressing mechanism 3 for pressing the glass is arranged on the side of the knocking table 2 away from the ground, and a vibration mechanism 4 is fixedly connected to the side of the pressing mechanism 3 away from the ground, and the vibration mechanism 4 is slidably connected to the Z guide rail 23. The cutting table 1 is rotatably connected to a feeding mechanism 5 for feeding the glass. The knocking table 2 is fixedly connected to an elastic table top, which is a sponge. The second Y guide rail 22 and the second Z guide rail 23 can move and lift the pressing mechanism 3 to adapt to cutting glass of different sizes, and the vibration mechanism 4 separates the cut glass by vibration and pressing. The determination of the positions of the first Y guide rail 12 and the like is controlled by the CNC table.

[0027] As another example, Figure 3 and Figure 4As shown, the pressing mechanism 3 of the present application includes a protective cover 31, a central gear 32, a rack 33, a pressing rod 34, a pressing head 35 and a first motor 36. The rack 33 is meshed with the central gear 32. The four racks 33 are arranged in a cross shape, and the four racks 33 are arranged in an up-down staggered manner. The racks 33 are parallel to the surface of the knocking table 2. The pressing rod 34 is vertically and fixedly connected to the end of each rack 33, and is located in the extension direction of the rack 33 rotating with the central gear 32. The pressing head 35 is detachably sleeved on one end of the pressing rod 34 close to the knocking table 2. The pressing head 35 and the pressing rod 34 are interference fit, and the disassembly and installation are achieved through the interference fit, which is convenient for replacing the pressing head 35. The pressing head 35 is a rubber sleeve. The four pressing heads 35 and the pressing rod 34 are all perpendicular to the surface of the knocking table 2. And the four racks 33 point to the four directions of the cross at one end of the fixed pressing rod 34. When the central gear 32 rotates forward or reversely, the four racks 33 move away from the central gear 32 or move toward the central gear 32 synchronously, so as to press the glass of different sizes. The height of each pressing head 35 close to the surface of the striking table 2 is consistent. In order to make the pressing force more balanced, a pressing rod 34 and a pressing head 35 are also fixed at the center of the protective cover 31.

[0028] The center of the central gear 32 away from the ground is fixedly connected to the output end of the first motor 36, the first motor 36 is fixedly connected to the inner wall of the protective cover 31, and the rack 33 passes through the protective cover 31. The protective cover 31 is fixedly connected to the limit rod 37, and the end of the limit rod 37 away from the protective cover 31 is fixedly connected to the limit ring 38, and the rack 33 is sleeved in the limit ring 38. The limit ring 38 can support the rack 33 so that the rack 33 remains stable during movement. The inner wall of the limit ring 38 close to the teeth of the rack 33 is arc-shaped, and the side of the protective cover 31 close to the teeth of the rack 33 is also arc-shaped. The arc shape can reduce the friction of the teeth and make the movement of the rack 33 smoother.

[0029] As another example, Figure 5 and Figure 6As shown, the vibration mechanism 4 of the present application includes a telescopic rod 41, a spring 42, a fixed plate 43, a fixed block 44, a second motor 45 and a shaped wheel 46. The spring 42 is sleeved in the telescopic rod 41. One end of the telescopic rod 41 is fixedly connected to the protective cover 31, and the other end of the telescopic rod 41 is fixedly connected to the fixed plate 43. One end of the fixed block 44 is fixedly connected to the end of the fixed plate 43 close to the ground, and the other end of the fixed block 44 is fixedly connected to the second motor 45. In this solution, two symmetrical second motors 45 are arranged to stabilize the vibration. The output end of the second motor 45 is fixedly connected to the center of the shaped wheel 46. The shaped wheel 46 is movably abutted against the protective cover 31. The width of the shaped wheel 46 is a regular polygon. In this solution, a regular dodecagon is used. During the rotation of the shaped wheel 46, the convex part continuously presses the protective cover 31. After being pressed and stretched, the spring 42 in the telescopic rod 41 quickly recovers, thereby generating high-frequency and small vibrations. The more sides of the shaped wheel 46 are closer to a circle, the smaller the vibration amplitude and the faster the frequency. The side of the fixing plate 43 away from the ground is fixedly connected to the Z-direction slider 24. The Z-direction slider 24 slides on the Z-guide rail 23, which can drive the fixing plate 43 to adjust the height, thereby driving the rack 33 and the pressing rod 34 to adjust the height, and the Z-guide rail 23 slides on the second Y-guide rail 22, and the second Y-guide rail 22 slides on the second X-guide rail 21, so that the position of the protective cover 31 can be adjusted, and then the rack 33 is driven by the first motor 36 to adjust the position of the pressing rod 34, and the second motor 45 rotates to generate vibration, so that the glass to be knocked off can be knocked out.

[0030] As another example, Figure 2 and Figure 7 As shown, the cutting table 1 of the present application is rotatably connected with a plurality of parallel conveyor belts 14 arranged at intervals, and the feeding mechanism 5 includes a rotating shaft 51, a folding tube 52, a plug-in tube 53 and a suction cup 54. The rotating shaft 51 is rotatably connected to the cutting table 1 along the width direction of the cutting table 1. The folding tube 52 is a tube with multiple bending nodes. One end of the folding tube 52 is fixedly connected to the rotating shaft 51, and the tube body of the folding tube 52 away from the rotating shaft 51 is fixedly and spacedly connected with a plurality of plug-in tubes 53. The suction cup 54 is sleeved on the plug-in tube 53, and the folding tube 52 is located in the gap between the conveyor belts 14. The suction cup 54 uses a vacuum suction cup 54, and the numerical control table controls the suction of air. A flexible pipe is connected in the folding tube 52 and the plug-in tube 53, so that when the suction cup 54 contacts the glass, the numerical control table can control the vacuuming to feed the material. After the folding tube 52 is extended to allow the suction cup 54 to absorb the glass, the folding tube 52 is folded to place the glass on the cutting table 1, and then the conveyor belt 14 conveys the glass to the cutting position. Reducing bumps during the loading process can also improve efficiency.

[0031] The working principle of a cutting device for producing fluorescent glass in the present application is as follows: when in use, the numerical control table controls the extension of the folding tube 52, and the vacuum is drawn by the suction cup 54 to suck the glass onto the cutting table 1, and then fills the glass with air, and runs the conveyor belt 14 to convey the glass to the bottom of the cutting head 13, and controls the first X-direction slider 112 to drive the first Y-direction guide rail 12 to move on the first X-direction guide rail 111, and the first Y-direction slider 121 slides on the first Y-direction guide rail 12 to cut the required size of the fluorescent glass. After the cutting is completed, the conveyor belt 14 conveys the glass to the knocking table 2, controls the second X-direction slider to drive the second Y-direction guide rail 22 to move on the second X-direction guide rail 21, and the second Y-direction slider slides on the second Y-direction guide rail 22. The pressing rod 34 located at the center of the protective cover 31 is located above the center of the glass to be knocked. The first motor 36 is rotated to drive the central gear 32 to rotate, so that the rack 33 is synchronously extended or shortened to adjust the position of the pressing rod 34 according to the size of the glass. The Z-direction guide rail 23 is adjusted, and the protective cover 31 is pressed down to press the glass. The second motor 45 is turned on to rotate, driving the shaped wheel 46 to rotate. The protrusion of the shaped wheel 46 continuously squeezes the fixed plate 43, and the spring 42 in the telescopic rod 41 is quickly reset after being pressed and stretched, thereby generating high-frequency and small vibrations, and the glass to be knocked out can be knocked out.

[0032] The above are only preferred embodiments of the present invention, and do not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above technical content without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any changes, modifications, equivalent changes and modifications made to the above embodiments based on the technology of the present invention without departing from the content of the technical solution of the present invention belong to the protection scope of the present technical solution.

Claims

1. A cutting device for fluorescent glass production, characterized in that: The invention comprises a cutting table (1) and a striking table (2), wherein the cutting table (1) is fixedly connected to the striking table (2), an X-direction guide rail (11) is fixedly connected to the edge of the cutting table (1), and the middle part of the X-direction guide rail (11) is divided into a first X-direction guide rail (111) and a second X-direction guide rail (21) by a partition plate (15), a first Y-direction guide rail (12) is slidably arranged along the width direction of the cutting table (1), a second Y-direction guide rail (22) is slidably arranged along the width direction of the striking table (2), and a cutting head (13) is slidably connected along the first Y-direction guide rail (12); A Z-direction guide rail (23) is slidably connected along the second Y-direction guide rail (22); a pressing mechanism (3) for pressing glass is provided on the side of the knocking table (2) away from the ground; a vibration mechanism (4) is fixedly connected to the side of the pressing mechanism (3) away from the ground; the vibration mechanism (4) is slidably connected to the Z-direction guide rail (23); and a loading mechanism (5) for loading glass is rotatably connected to the cutting table (1).

2. The cutting device for producing fluorescent glass according to claim 1, characterized in that: A first X-direction slider (112) is slidably connected along the first X-direction guide rail (111); a side of the first X-direction slider (112) away from the ground is fixedly connected to the end of the first Y-direction guide rail (12); a first Y-direction slider (121) is slidably connected to the first Y-direction guide rail (12); and the first Y-direction slider (121) is fixedly connected to the cutting head (13); The second X-direction guide rail (21) is slidably connected to a second X-direction slider, the side of the second X-direction slider away from the ground is fixedly connected to the end of the second Y-direction guide rail (22), the Z-direction guide rail (23) slides on the second Y-direction guide rail (22), and the Z-direction slider (24) is slidably connected to the Z-direction guide rail (23).

3. The cutting device for producing fluorescent glass according to claim 2, characterized in that: The pressing mechanism (3) comprises a protective cover (31), a central gear (32), a rack (33), a pressing rod (34), a pressing head (35) and a first motor (36); the rack (33) is meshed with the central gear (32); four racks (33) are arranged in a cross shape, and the four racks (33) are arranged in an up-down staggered manner; the racks (33) are parallel to the table surface of the striking table (2); the pressing rod (34) is vertically and fixedly connected to the end of each rack (33); Located in the extending direction of the rack (33) rotating with the central gear (32), the pressing head (35) is detachably sleeved on an end of the pressing rod (34) close to the striking platform (2), the pressing head (35) and the pressing rod (34) are interference fit, the center of the central gear (32) away from the ground is fixedly connected to the output end of the first motor (36), the first motor (36) is fixedly connected to the inner wall of the protective cover (31), and the rack (33) passes through the protective cover (31).

4. The cutting device for producing fluorescent glass according to claim 3, characterized in that: The vibration mechanism (4) comprises a telescopic rod (41), a spring (42), a fixed plate (43), a fixed block (44), a second motor (45) and a shaped wheel (46); the spring (42) is sleeved in the telescopic rod (41); one end of the telescopic rod (41) is fixedly connected to the protective cover (31); the other end of the telescopic rod (41) is fixedly connected to the fixed plate (43); one end of the fixed block (44) is fixedly connected to an end of the fixed plate (43) close to the ground; the other end of the fixed block (44) is fixedly connected to the second motor (45); an output end of the second motor (45) is fixedly connected to the center of the shaped wheel (46); the shaped wheel (46) is movably abutted against the protective cover (31); and a side of the fixed plate (43) away from the ground is fixedly connected to the Z-direction slider (24).

5. The cutting device for producing fluorescent glass according to claim 1, characterized in that: The cutting table (1) is rotatably connected to a plurality of parallel conveyor belts (14) arranged at intervals. The feeding mechanism (5) comprises a rotating shaft (51), a folded tube (52), a plug-in tube (53) and a suction cup (54). The rotating shaft (51) is rotatably connected to the cutting table (1) along the width direction of the cutting table (1). The folded tube (52) is a tube with a plurality of bending nodes. One end of the folded tube (52) is fixedly connected to the rotating shaft (51). The tube body of the folded tube (52) at one end away from the rotating shaft (51) is fixedly and spacedly connected to a plurality of plug-in tubes (53). The suction cup (54) is sleeved on the plug-in tube (53). The folded tube (52) is located in the gap between the conveyor belts (14).

6. The cutting device for producing fluorescent glass according to claim 3, characterized in that: The knocking table (2) is fixedly connected with an elastic tabletop.

7. The cutting device for producing fluorescent glass according to claim 3, characterized in that: The protective cover (31) is fixedly connected to a limiting rod (37), one end of the limiting rod (37) away from the protective cover (31) is fixedly connected to a limiting ring (38), and the rack (33) is sleeved in the limiting ring (38).

8. The cutting device for producing fluorescent glass according to claim 7, characterized in that: The inner wall of the limiting ring (38) close to the tooth of the rack (33) is arc-shaped.

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