Automatic annealing device for metal pen container
By designing an automatic annealing device, the problem of stress elimination after metal pen barrel processing is solved, the automatic annealing of the pen barrel is realized, the hardness and wear resistance are increased, and the writing performance is improved.
Patent Information
- Application Number
- CN202510783671.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-12
- Publication Date
- 2025-09-19
AI Technical Summary
The existing technology lacks an automated metal pen barrel annealing device, which results in the inability to effectively eliminate stress after the pen barrel is processed, affecting the hardness, wear resistance and writing performance.
An automatic annealing device for metal pen holders was designed, which included a screw feeder, a heater, and a blanking assembly. The rolling speed and heating time of the pen holder in the heating element were controlled by adjusting the assembly, and the contact length between the pressure plane and the pen holder was adjusted by the rotating element to achieve automatic annealing of the pen holder.
The automatic annealing of the pen barrel is realized, which eliminates internal stress, improves hardness and wear resistance, and improves writing fluency and comfort.
Smart Images

Figure CN120666162A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to annealing technology, in particular to an automatic annealing device for a metal pen holder. Background Art
[0002] High-end fountain pens are currently mainly made of metal, and the metal pen barrel will have stress after manufacturing and processing, so the pen barrel needs to be heated and annealed. Annealing is a type of heat treatment, which can increase the toughness of the material and change its shape later. When annealing the pen barrel, the metal pen barrel is slowly heated to a certain temperature, kept for a sufficient time, kept at a specific temperature for a period of time, and then cooled at an appropriate rate, usually slow cooling, sometimes controlled cooling. The main purpose of the annealing treatment is to improve its physical and mechanical properties by changing the internal structure of the metal. Specifically for metal pens, annealing can eliminate internal stress, increase the hardness and wear resistance of the pen tip, and extend its service life. In addition, annealing can also improve the writing smoothness and comfort of the pen tip. Therefore, a device for automatic annealing of metal pen barrels is needed. Summary of the Invention
[0003] In order to solve the defects of the above-mentioned prior art, the present invention proposes an automatic annealing device for a metal pen holder.
[0004] The technical solution of the present invention is achieved as follows:
[0005] An automatic annealing device for a metal pen holder, comprising:
[0006] A workbench, on which a screw feeder, a heater, and a blanking assembly cooperating with the screw feeder are provided. The blanking assembly is connected to the screw feeder via a connecting pipe. The heater is provided with a heating element cooperating with the blanking assembly, and the heating element is arranged on one side of the blanking assembly.
[0007] An adjusting assembly provided on the blanking assembly, the adjusting assembly comprising:
[0008] A base mounted on the blanking assembly, wherein a fixing plate is provided at the lower end of the base, and the base is docked with the blanking assembly via the fixing plate. The base is further provided with symmetrically arranged support plates, wherein the support plates are provided with transverse grooves and vertical grooves. The base is further provided with a through hole, wherein the through hole is located between the symmetrically arranged support plates;
[0009] A pressing member is arranged in the through hole, wherein the lower end of the pressing member is provided with a receiving groove that cooperates with the vertical groove;
[0010] A rotating member is provided on the base, the rotating member is located at the upper end of the pressing member, and the rotating member is rotated to keep the pressing member moving in the through hole;
[0011] And an adjusting member installed in the accommodating groove and the vertical groove, after the middle of the adjusting member is pushed downward by the pressing member, the two ends of the adjusting member are kept rotating with the pressing member as the fulcrum to change the position between the adjusting member and the blanking assembly.
[0012] In the present invention, the blanking assembly consists of a base plate, a first support block, a second support block, a first mounting plate, a second mounting plate, a fixed plate and a connecting plate. The first support block and the second support block are arranged on both sides of the base plate, the first mounting plate is arranged on the first support block, the fixed plate is arranged at both ends of the second support block, and the fixed plate is connected to the second mounting plate through a connecting plate.
[0013] In the present invention, a strip groove is provided on the bottom plate near the second support block, a hollow area is formed between the fixed plates, the hollow area is at the upper end of the strip groove, and a through area for accommodating the bottom plate and the second support block is formed in the middle of the heating element.
[0014] In the present invention, a first mounting groove and a second mounting groove are provided on the first mounting plate and the second mounting plate, a first fixing foot and a second fixing foot are provided at the lower end of the fixing plate, the second fixing foot is connected to the fixing plate through a contact section, the first fixing foot cooperates with the first mounting groove, and the second fixing foot cooperates with the second mounting groove.
[0015] In the present invention, an avoidance surface is provided in the first installation groove, an avoidance opening is provided between the first fixing foot and the fixing plate, an arc portion is provided at the lower end of the first fixing foot, an arc surface is provided at the lower end of the arc portion, and a contact surface is provided at the upper end.
[0016] In the present invention, an inclined groove is provided in the second mounting groove, and protrusions are provided on both sides of the inclined groove. An inclined plate is provided at the lower end of the second fixed leg, and a compression area is formed between the inclined plate and the second fixed leg. The inclined plate is arranged in the inclined groove, and a limiting surface that cooperates with the protrusion is formed on the inclined plate. The limiting surface is at the lower end of the protrusion, and a sliding plate is also provided on the inclined plate.
[0017] In the present invention, a transverse plate and a vertical plate are provided on the base, a threaded hole is provided on the transverse plate, and a hexagonal portion and a threaded portion are provided on the rotating member, and the threaded portion is installed in cooperation with the threaded hole.
[0018] In the present invention, the adjusting member consists of an installation section and a symmetrically arranged first inclined section, a connecting section, and a second inclined section. The first inclined section is connected to the second inclined section through the connecting section. The installation section is arranged in the accommodating groove and the vertical groove. The first inclined section and the second inclined section are not parallel, and the first inclined section is arranged parallel to the blanking assembly.
[0019] In the present invention, a pressure plane is provided on the second inclined section.
[0020] In the present invention, a convex arc surface is provided in the receiving groove, and the convex arc surface is in tangential contact with the mounting section.
[0021] The automatic annealing device for a metal pen holder according to the present invention has the following beneficial effects: by providing a through area on the heating element, the automatic annealing device for a metal pen holder can cooperate with the blanking assembly to heat the pen holder through one end, thereby achieving annealing of the pen holder. In addition, by rotating the rotating element, the rotating element can be kept pressing the pressing element, keeping the middle of the mounting section on the adjusting element deformed downward under force, and causing the two ends of the mounting section to rotate in the vertical groove around the center of the raised arc surface, thereby causing the pressure plane to rotate a certain angle, changing the linear contact length between the pressure plane and the pen holder, controlling the rolling speed of the pen holder, and adjusting the annealing time of the pen holder. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a schematic structural diagram of the automatic annealing device for a metal pen holder of the present invention;
[0023] Figure 2 for Figure 1 The main view;
[0024] Figure 3 for Figure 1 Schematic diagram of the structure of the middle and lower material components and the heating element;
[0025] Figure 4 for Figure 3 The main perspective view;
[0026] Figure 5 for Figure 4 A local enlarged view of point A in FIG;
[0027] Figure 6 for Figure 4 A local enlarged view of point B in FIG;
[0028] Figure 7 for Figure 3 Exploded diagram;
[0029] Figure 8 for Figure 7 Schematic diagram of the heating element structure;
[0030] Figure 9 for Figure 7 Schematic diagram of the blanking component structure;
[0031] Figure 10 for Figure 9 A schematic structural diagram of the first mounting plate in FIG.
[0032] Figure 11for Figure 10 A local enlarged view of point C in FIG;
[0033] Figure 12 for Figure 7 Schematic diagram of the regulation component structure in ;
[0034] Figure 13 for Figure 12 Another state diagram;
[0035] Figure 14 for Figure 12 Exploded diagram;
[0036] Figure 15 for Figure 14 Schematic diagram of the regulating member structure;
[0037] Figure 16 for Figure 14 A perspective view of the pressing member structure in FIG;
[0038] Figure 17 for Figure 14 The main view of the base structure in ;
[0039] Figure 18 for Figure 14 Schematic diagram of the base structure in FIG;
[0040] Figure 19 for Figure 18 A local enlarged view of point D in FIG;
[0041] Figure 20 This is a schematic diagram of the installation state of the pressing member and the adjusting member structure in the present invention.
[0042] In the figure: workbench 1, adjustment component 2, screw feeder 3, heater 4, blanking component 5, connecting pipe 6, heating element 7, bottom plate 8, first support block 9, second support block 10, first mounting plate 11, second mounting plate 12, fixing plate 13, connecting plate 14, strip groove 15, through area 16, first arc segment 17, second arc segment 18, upper bridge pipe 19, lower bridge pipe 20, second mounting block 21, observation area 22, through area 23, adjustment member 24, first mounting groove 25, second mounting groove 26, first fixed foot 27, second fixed foot 28, contact section 29, first Inclined section 30, connecting section 31, second inclined section 32, placement groove 33, avoidance opening 34, arc-shaped portion 35, arc-shaped surface 36, contact surface 37, base 38, inclined groove 39, raised portion 40, inclined plate 41, compression area 42, limiting surface 43, sliding plate 44, avoidance surface 45, pressing member 46, rotating member 47, retaining plate 48, support plate 49, transverse groove 50, vertical groove 51, through hole 52, transverse plate 53, vertical plate 54, threaded hole 55, hexagonal portion 56, threaded portion 57, raised arc surface 58, pressure plane 59, accommodating groove 60, mounting section 61, positioning block 62. DETAILED DESCRIPTION
[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.
[0044] Example 1
[0045] like Figures 1 to 20 As shown, the automatic annealing device for a metal pen holder of the present invention comprises a workbench 1 and an adjustment assembly 2. The workbench 1 is provided with a screw feeder 3, a heater 4, and a blanking assembly 5 that cooperates with the screw feeder 3. The blanking assembly 5 is connected to the screw feeder 3 via a connecting pipe 6. The heater 4 is provided with a heating element 7 that cooperates with the blanking assembly 5. The heating element 7 is arranged on one side of the blanking assembly 5.
[0046] The screw feeder 3 can be existing technology, so it will not be elaborated here. The screw feeder 3 realizes automatic loading, and is then connected to the blanking component 5 through the connecting pipe 6, so that the pen barrel that needs to be annealed reaches the blanking component 5 through the connecting pipe 6, and is thereby heated by the heating element 7 connected to the heater 4. Then, the adjusting component 2 on the blanking component 5 controls the rolling speed of the pen barrel, thereby adjusting the heating time of the pen barrel in the middle of the heating element 7, which is convenient for the staff to adjust the speed and heating time according to different pen barrel models and different metals.
[0047] like Figure 9As shown, the blanking assembly 5 consists of a base plate 8, a first support block 9, a second support block 10, a first mounting plate 11, a second mounting plate 12, a fixed plate 13, and a connecting plate 14. The first support block 9 and the second support block 10 are arranged on both sides of the base plate 8, the first mounting plate 11 is arranged on the first support block 9, and the fixed plate 13 is arranged at both ends of the second support block 10. The fixed plate 13 is connected to the second mounting plate 12 via the connecting plate 14. The base plate 8, the first support block 9, the second support block 10, the first mounting plate 11, and the fixed plate 13 are connected by bolts, while the fixed plate 13, the connecting plate 14, and the second mounting plate 12 can be connected by welding.
[0048] A strip groove 15 is provided on the bottom plate 8 near the second support block 10, and a hollow area is formed between the fixing plates 13. The hollow area is at the upper end of the strip groove 15, and a through area 16 for accommodating the bottom plate 8 and the second support block 10 is formed in the middle of the heating element 7.
[0049] like Figure 8 As shown, the heating element 7 is composed of a tube body, which is connected to the heater 4 at both ends. A plurality of first arc segments 17 and second arc segments 18 are formed in the middle of the tube body, as well as an upper bridge pipe 19 and a lower bridge pipe 20 for connecting the first arc segments 17 and the second arc segments 18. The upper bridge pipe 19 and the lower bridge pipe 20 form the through-region 16. The upper bridge pipe 19 is located at the upper end of the second mounting block 21, while the lower bridge pipe 20 is located at the lower end of the bottom plate 8, keeping the second mounting block 21 and the bottom plate 8 in the through-region 16. Therefore, when the heater 4 is started, the pen barrel rolling on the bottom plate 8 can be heated by the heating element 7.
[0050] An observation area 22 is formed between the first mounting plate 11 and the second mounting plate 12, allowing staff to observe the pen barrel's rolling state. A passage area 23 is formed between the first mounting plate 11, the second mounting plate 12, and the bottom plate 8 to ensure the pen barrel can roll within it. An adjustment member 24 extends into the passage area 23 to provide resistance to the pen barrel's rolling, thereby ensuring the pen barrel's heating time.
[0051] The first mounting plate 11 and the second mounting plate 12 are provided with a first mounting groove 25 and a second mounting groove 26. The lower end of the fixing plate 13 is provided with a first fixing foot 27 and a second fixing foot 28. The second fixing foot 28 is connected to the fixing plate 13 via a contact section 29. The first fixing foot 27 cooperates with the first mounting groove 25, and the second fixing foot 28 cooperates with the second mounting groove 26.
[0052] The first mounting plate 11 is further provided with a placement groove 33 for accommodating the first inclined section 30 , the connecting section 31 and the second inclined section 32 , so that the second inclined section 32 can enter the passing area 23 to generate resistance to the pen holder.
[0053] The first mounting groove 25 is provided with a clearance surface 45, and a clearance opening 34 is provided between the first fixing leg 27 and the fixing plate 13. The lower end of the first fixing leg 27 is provided with an arcuate portion 35, the lower end of which is provided with an arcuate surface 36, and the upper end of which is provided with a contact surface 37. The width of the first mounting groove 25 is greater than the width of the first fixing leg 27, but smaller than the diameter of the arcuate portion 35. During installation, the base 38 needs to be tilted and then cleared of the fixing plate 13 through the clearance opening 34, ensuring that the base 38 can rotate and the arcuate portion 35 is placed in the first mounting groove 25.
[0054] An inclined groove 39 is provided in the second mounting groove 26, and protrusions 40 are provided on both sides of the inclined groove 39. An inclined plate 41 is provided at the lower end of the second fixed leg 28, and a compression area 42 is formed between the inclined plate 41 and the second fixed leg 28. The inclined plate 41 is arranged in the inclined groove 39, and a limiting surface 43 is formed on the inclined plate 41 to cooperate with the protrusion 40. The limiting surface 43 is located at the lower end of the protrusion 40, and a sliding plate 44 is also provided on the inclined plate 41.
[0055] During installation, the limiting surface 43 on the inclined plate 41 is kept to reach the lower end of the protrusion 40 , so that the position of the inclined plate 41 is limited by the protrusion 40 .
[0056] When the adjusting member 24 needs to be replaced later, the sliding plate 44 can be pushed first, so that the sliding plate 44 drives the inclined plate 41 to be forced to move closer to the compression area 42, keeping the limiting surface 43 separated from the protrusion 40, and then keeping the first fixed foot 27 on the base 38 first sliding in the direction of the avoidance surface 45 in the first mounting groove 25, and then the base 38 is rotated around the first fixed foot 27, and the first fixed foot 27 is placed at the avoidance surface 45, so that the arc portion 35 can be removed from the lower end of the first mounting groove 25 and the adjusting member 24 can be replaced.
[0057] Example 2
[0058] The adjustment assembly 2 is mounted on the blanking assembly 5 and includes a base 38, a pressing member 46, a rotating member 47, and an adjustment member 24. The base 38 is mounted on the first mounting plate 11 and the second mounting plate 12. The pressing member 46 is mounted on the base 38. The rotating member 47 is located at the upper end of the pressing member 46 and is located on the base 38. The adjustment member 24 is located on the base 38 but is limited in position by the pressing member 46.
[0059] The base 38 is mounted on the blanking assembly 5. A fixing plate 13 is provided at the lower end of the base 38. The base 38 is also provided with a retaining plate 48. The retaining plate 48 is arranged perpendicular to the fixing plate 13 and is placed on the first mounting plate 11 and the second mounting plate 12 via the fixing plate 13. The base 38 is docked with the blanking assembly 5 via the fixing plate 13. The base 38 is also provided with symmetrically arranged support plates 49, each of which is provided with a transverse groove 50 and a vertical groove 51. The base 38 is also provided with a through hole 52, which is located between the symmetrically arranged support plates 49.
[0060] The base 38 is further provided with a transverse plate 53 and a vertical plate 54. The transverse plate 53 is provided with a threaded hole 55. The rotating member 47 is provided with a hexagonal portion 56 and a threaded portion 57, and the threaded portion 57 is mounted in conjunction with the threaded hole 55. Rotating the hexagonal portion 56 allows the threaded portion 57 to engage with the threaded hole 55, thereby pushing the pressing member 46 to move within the through hole 52, applying pressure to the adjusting member 24. The first inclined section 30, the connecting section 31, and the second inclined section 32 at both ends of the adjusting member 24 are kept slightly rotated about the center of the convex arc surface 58, so that the contact between the pressure plane 59 and the pen barrel is reduced, thereby reducing the resistance to the pen barrel, accelerating the speed at which the pen barrel rolls down, and shortening the heating time.
[0061] The pressing member 46 is disposed within the through-hole 52. The lower end of the pressing member 46 is provided with a receiving groove 60 that mates with the vertical groove 51. A raised arcuate surface 58 is provided within the receiving groove 60, which tangentially contacts the mounting section 61. The upper end of the pressing member 46 is also provided with a symmetrically arranged positioning block 62, which prevents displacement of the pressing member 46 as it moves up and down within the through-hole 52.
[0062] The rotating member 47 is disposed on the base 38 and is located at the upper end of the pressing member 46 . The rotating member 47 is rotated to keep the pressing member 46 moving in the through hole 52 .
[0063] The adjusting member 24 is installed in the accommodating groove 60 and the vertical groove 51. After the middle of the adjusting member 24 is pushed downward by the pressing member 46, the two ends of the adjusting member 24 are kept rotating with the pressing member 46 as the fulcrum to change the position between the adjusting member 24 and the blanking assembly 5.
[0064] The adjusting member 24 consists of a mounting section 61 and a symmetrically arranged first inclined section 30, a connecting section 31, and a second inclined section 32. The first inclined section 30 is connected to the second inclined section 32 through the connecting section 31. The mounting section 61 is arranged in the accommodating groove 60 and the vertical groove 51. The first inclined section 30 and the second inclined section 32 are not parallel, and the first inclined section 30 is arranged parallel to the blanking component 5.
[0065] A pressure plane 59 is provided on the second inclined section 32. The pressure plane 59 maintains linear contact with the outer wall of the pen holder. When the entire width of the pressure plane 59 is in contact with the pen holder, the resistance level N1 exerted by the second inclined section 32 on the pen holder is generated. When the rotating member 47 applies pressure to the pressing member 46, the pressing member 46 applies pressure to the mounting section 61 of the adjusting member 24, causing the first inclined section 30, the connecting section 31, and the second inclined section 32 to rotate slightly. This causes the pressure plane 59 to no longer appear as a straight line when viewed from the main view direction, but rather as a smaller plane. This means that the first inclined section 30, the connecting section 31, and the second inclined section 32 rotate about the raised arc surface 58, toward the center of the two second inclined sections 32. This shortens the contact line between the pressure plane 59 on the second inclined section 32 and the outer wall of the pen holder, resulting in a resistance level N2 of the second inclined section 32, where N1>N2.
[0066] Because the convex arc surface 58 is provided within the receiving groove 60, when the pressing member 46 applies pressure to the mounting section 61, the mounting section 61 is gradually subjected to force, keeping the mounting section 61 in contact with the convex arc surface 58. The force applied to the mounting section 61 changes from the original horizontal rod to the arc rod, and the mounting section 61 gradually contacts the convex arc surface 58, causing the mounting section 61 to deform under force and generate elastic potential energy. When the rotating member 47 is rotated in the opposite direction, the rotating member 47 no longer applies pressure to the pressing member 46, and the mounting section 61 returns to its original position due to its own elastic potential energy.
[0067] Since the second inclined section 32 is rotated when it moves, rather than being moved directly up and down, the resistance exerted by the second inclined section 32 on the pen holder can be adjusted. In this case, the distance between the second inclined section 32 and the bottom plate 8 remains unchanged, thereby effectively reducing the resistance exerted on the pen holder.
[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. An automatic annealing device for a metal pen holder, characterized in that: include: A workbench, on which a screw feeder, a heater, and a blanking assembly cooperating with the screw feeder are provided. The blanking assembly is connected to the screw feeder via a connecting pipe. The heater is provided with a heating element cooperating with the blanking assembly, and the heating element is arranged on one side of the blanking assembly. An adjusting assembly provided on the blanking assembly, the adjusting assembly comprising: A base mounted on the blanking assembly, wherein a fixing plate is provided at the lower end of the base, and the base is docked with the blanking assembly via the fixing plate. The base is further provided with symmetrically arranged support plates, wherein the support plates are provided with transverse grooves and vertical grooves. The base is further provided with a through hole, wherein the through hole is located between the symmetrically arranged support plates; A pressing member is arranged in the through hole, wherein the lower end of the pressing member is provided with a receiving groove that cooperates with the vertical groove; A rotating member is provided on the base, the rotating member is located at the upper end of the pressing member, and the rotating member is rotated to keep the pressing member moving in the through hole; And an adjusting member installed in the accommodating groove and the vertical groove, after the middle of the adjusting member is pushed downward by the pressing member, the two ends of the adjusting member are kept rotating with the pressing member as the fulcrum to change the position between the adjusting member and the blanking assembly.
2. The automatic annealing device for a metal pen holder according to claim 1, characterized in that: The blanking assembly consists of a base plate, a first support block, a second support block, a first mounting plate, a second mounting plate, a fixed plate and a connecting plate. The first support block and the second support block are arranged on both sides of the base plate, the first mounting plate is arranged on the first support block, the fixed plate is arranged at both ends of the second support block, and the fixed plate is connected to the second mounting plate through a connecting plate.
3. The automatic annealing device for a metal pen holder according to claim 2, characterized in that: A strip groove is provided on the bottom plate near the second support block, a hollow area is formed between the fixed plates, the hollow area is at the upper end of the strip groove, and a through area for accommodating the bottom plate and the second support block is formed in the middle of the heating element.
4. The automatic annealing device for a metal pen holder according to claim 3, characterized in that: A first mounting groove and a second mounting groove are provided on the first mounting plate and the second mounting plate, a first fixing foot and a second fixing foot are provided at the lower end of the fixing plate, the second fixing foot is connected to the fixing plate through a contact section, the first fixing foot cooperates with the first mounting groove, and the second fixing foot cooperates with the second mounting groove.
5. The automatic annealing device for a metal pen holder according to claim 4, characterized in that: An avoidance surface is provided in the first installation groove, an avoidance opening is provided between the first fixing leg and the fixing plate, an arc portion is provided at the lower end of the first fixing leg, an arc surface is provided at the lower end of the arc portion, and a contact surface is provided at the upper end.
6. The automatic annealing device for a metal pen holder according to claim 5, characterized in that: An inclined groove is provided in the second mounting groove, and protrusions are provided on both sides of the inclined groove. An inclined plate is provided at the lower end of the second fixed leg, and a compression area is formed between the inclined plate and the second fixed leg. The inclined plate is arranged in the inclined groove, and a limiting surface is formed on the inclined plate to cooperate with the protrusion. The limiting surface is at the lower end of the protrusion, and a sliding plate is also provided on the inclined plate.
7. The automatic annealing device for a metal pen holder according to claim 1, characterized in that: The base is provided with a transverse plate and a vertical plate, the transverse plate is provided with a threaded hole, the rotating member is provided with a hexagonal portion and a threaded portion, and the threaded portion is installed in cooperation with the threaded hole.
8. The automatic annealing device for a metal pen holder according to claim 1, characterized in that: The adjusting member consists of an installation section and a symmetrically arranged first inclined section, a connecting section, and a second inclined section. The first inclined section is connected to the second inclined section through the connecting section. The installation section is arranged in the accommodating groove and the vertical groove. The first inclined section and the second inclined section are not parallel, and the first inclined section is arranged parallel to the blanking assembly.
9. The automatic annealing device for a metal pen holder according to claim 8, characterized in that: A pressure plane is provided on the second inclined section.
10. The automatic annealing device for a metal pen holder according to claim 9, characterized in that: A convex arc surface is provided in the accommodating groove, and the convex arc surface is in tangential contact with the mounting section.