Various nail guns and their nail guides

Abstract

A variety of nail guns and their nail guides are disclosed. The nail guide includes a base plate and an extension assembly surrounding the base plate to define a nail receiving space. The base plate includes a base wall and a recess. The base wall has a flat rear side surface and two abutment surfaces. The recess has a groove bottom surface spaced apart from the abutment surfaces and two groove peripheral side surfaces. Each groove peripheral side surface is substantially perpendicularly connected to the corresponding abutment surface in a front-back direction. The extension assembly and the base plate are integrally injection molded. Through integral injection molding, each groove peripheral side surface and the corresponding abutment surface form a right-angled platform to generate sufficient abutment area, ensuring that the nail can be firmly supported by the abutment surface, achieving the effect of stable nail delivery.

Description

[Technical Field]

[0001] This invention relates to a handheld firing tool for injecting needles, and more particularly to a variety of needle guns and their needle guides. [Previous Technology]

[0002] Referring to Figures 1 and 2, Republic of China Patent Publication No. TW202504731A discloses a guide pin component and a nail gun including the guide pin component. The nail gun includes a cover 100, a nail rail 110 suitable for mounting a plurality of nails 10, and a guide pin component 1. The cover 100 is used to cover the nails 10 and has two guide ribs 101 (only one guide rib 101 is shown in the figure due to the viewing angle). The guide pin component 1 is a single integrally formed component and includes a plate 11 with a three-tiered platform structure. The plate 11 has a first side surface 111, a second side surface 112 opposite to the first side surface 111, a first groove 113 recessed in the first side surface 111, and two second grooves 114 recessed in the first side surface 111 and located on the left and right sides of the first groove 113.

[0003] The guide pin component 1 is manufactured by stamping. After the material (i.e., the plate 11) is placed into the stamping die, pressure is applied to shape it into the desired form. Although the aforementioned metal stamping process has the advantage of high production efficiency, it is limited by the die, and the processing accuracy is somewhat restricted. As shown in Figure 1, the second side 112 of the plate 11 will have a protrusion or depression relative to the first side 111 (i.e., when the first side 111 is depressed, the second side 112 is convex, and vice versa), resulting in poor flatness.

[0004] Furthermore, as shown in Figure 3, due to the limitations of the stamping process, the stepped portion of the aforementioned three-tiered platform structure (i.e., the junction of the first groove 113 and the second groove 114) will form a slightly curved transition, and a right-angled platform cannot be formed. Therefore, when one of the pins 10 is placed in the second groove 114, it is easy to move from the second groove 114 to the first groove 113 due to skewness, causing the pin 10 to be unable to be stably supported by the second groove 114, thereby affecting the stability of the pin delivery. [Summary of the Invention]

[0005] Therefore, the object of the present invention is to provide a guide pin with high flatness and improved needle delivery stability.

[0006] Therefore, the guide pin of the present invention is suitable for mounting in a housing unit of a variety of nail guns. The guide pin includes a base plate and an extension assembly.

[0007] The substrate includes a base wall extending in a vertical direction and a groove formed in the base wall. The base wall has a flat rear side surface, a front side surface opposite to the rear side surface in a front-rear direction, and two abutment surfaces opposite to the rear side surface in the front-rear direction. The groove is recessed in the front side surface and has a groove bottom surface spaced apart from the abutment surfaces in the front-rear direction, and two groove peripheral side surfaces respectively connected to the left and right sides of the groove bottom surface. Each groove peripheral side surface is substantially perpendicularly connected to the corresponding abutment surface in the front-rear direction, and each abutment surface is spaced apart from the groove bottom surface by a first distance (D1) in the front-rear direction.

[0008] The extension assembly and the substrate are integrally injection molded, and together with the substrate, define a needle-receiving space. The extension assembly includes a first extension wall and a second extension wall spaced apart along a left-right direction and extending from the front side away from the rear side, and has two extension wall surfaces respectively formed on the side of the first extension wall and the second extension wall opposite to the base wall. Each extension wall surface is spaced apart from the corresponding abutment surface along the front-rear direction, and is spaced apart from the bottom surface of the groove by a second distance (D2) along the front-rear direction, where D2:D1 is between 8:1 and 4:1. The left-right direction is substantially perpendicular to the up-down direction and the front-rear direction.

[0009] Therefore, another object of the present invention is to provide a variety of needle guns that can improve the stability of needle delivery.

[0010] Thus, the present invention provides a variety of nail guns, comprising a housing unit, a nail rail, a nail guide as described above, a nail guide seat, and a nail-driving blade.

[0011] The housing unit surrounds and defines an accommodating space.

[0012] The nail rail is provided in the receiving space and is suitable for providing several nails.

[0013] The guide pin is disposed in the receiving space.

[0014] The guide pin seat is connected to the pin rail and faces the guide pin member. The guide pin seat and the guide pin member cooperate to define a space that communicates with the pin receiving space and has a downward-facing nail hole.

[0015] The hammerhead is disposed in the receiving space and is operable to move in a vertical direction. The hammerhead is positioned above the nail hole in the vertical direction and is adapted to drive one of the nails out of the nail hole.

[0016] The advantages of this invention are:

[0017] 1. The extension assembly and the substrate are integrally injection molded. Since injection molding uses a mold to directly shape the material, there will be no material deformation problem during the stamping process, resulting in good flatness. In addition, the right-angled platform formed by integral injection molding (i.e., each groove peripheral side and the corresponding abutment surface) generates sufficient abutment area to ensure that the pin can be firmly supported by the abutment surface, thereby achieving the effect of stable pin delivery.

[0018] 2. By means of the structural design that the second distance (D2) is greater than the first distance (D1), compared with the conventional method of using the guide rib of the cover to guide the nail, the first extension wall and the second extension wall of the present invention can directly achieve the effect of guiding the nail set on the nail rail and making the nail properly positioned. Therefore, the present invention can also save the cost of setting an additional cover.

Implementation Method

[0019] Before this embodiment is described in detail, it should be noted that similar elements are represented by the same number in the following description.

[0020] Referring to Figures 4, 5, and 6, an embodiment of the various types of nail guns of the present invention is shown, suitable for setting several types of nails 9. In this embodiment, the user can select and set a single type of nail 9, such as any one of U-shaped, U-shaped, or T-shaped nails, in a single operation according to practical needs. The various types of nail guns include a housing unit 2, a nail rail 3, a nail guide 4, a nail guide seat 7, and a nail-driving blade 8.

[0021] The housing unit 2 surrounds and defines an accommodating space 20, and includes a top-mounted and operable pressure handle 21.

[0022] The nail rail 3 extends along a front-rear direction Y and is disposed in the receiving space 20. In this embodiment, the nail rail 3 is adapted to accommodate the nails 9.

[0023] The guide pin 4 is installed in the housing unit 2 and disposed in the receiving space 20, and includes a base plate 5 and an extension assembly 6.

[0024] Referring to Figures 7, 8, and 9, the substrate 5 has a base wall 51 extending in a vertical direction Z, and a groove 52 formed in the base wall 51. The base wall 51 has a flat rear side surface 511, a front side surface 512 opposite to the rear side surface 511 in a front-rear direction Y, and two abutment surfaces 513 opposite to the rear side surface 511 in the front-rear direction Y. The front side surface 512 faces the nail rail 3, and the abutment surfaces 513 are spaced apart in a left-right direction X. The left-right direction X is substantially perpendicular to the vertical direction Z and the front-rear direction Y.

[0025] Referring to Figures 7, 8 and 10, the groove portion 52 is recessed on the front side surface 512 and has a groove bottom surface 521 that is spaced apart from the abutting surface 513 along the front-rear direction Y, two groove peripheral side surfaces 522 that are respectively connected to the left and right sides of the groove bottom surface 521, a groove peripheral top surface 523 that is respectively connected to the groove peripheral side surfaces 522 at two opposite ends along the left-right direction X, a first protruding rib 524 that extends along the vertical direction Z and protrudes from the groove bottom surface 521, and two second protruding ribs 525 that extend along the vertical direction Z and protrude from the groove bottom surface 521.

[0026] Each of the groove peripheral side surfaces 522 is substantially perpendicularly connected to the groove bottom surface 521 and the corresponding abutment surface 513 on opposite sides along the front-rear direction Y. Each abutment surface 513 is separated from the groove bottom surface 521 by a first distance D1 along the front-rear direction Y. Each groove peripheral side surface 522 and the corresponding abutment surface 513 form an angle (not shown), which is between 85° and 95°, for example, 90°.

[0027] By integral injection molding, each of the groove peripheral side surfaces 522 is perpendicularly connected to the right-angled platform formed by the groove bottom surface 521 and the corresponding abutment surface 513 on opposite sides along the front-back direction Y, thereby generating sufficient abutment area to ensure that the nail can be firmly supported by the abutment surface 513 without shifting towards the groove bottom surface 521. Therefore, this embodiment does have the effect of stabilizing the needle delivery.

[0028] Referring to Figures 7, 8, and 9, the second ribs 525 are spaced apart along the left-right direction X and are located to the right of the first rib 524. In this embodiment, the first rib 524 and the second ribs 525 are essentially protruding strips. The length of each second rib 525 extending along the up-down direction Z is less than the length of the first rib 524 extending along the up-down direction Z, and a downwardly extending inclined surface 526 is formed on the top side of each second rib 525.

[0029] Referring to Figures 7, 8, and 10, the extension assembly 6 and the substrate 5 are integrally injection molded, and together with the substrate 5, define a needle-receiving space 40 facing the nail rail 3 and suitable for accommodating the nails 9. The extension assembly 6 has a first extension wall 61 and a second extension wall 62 spaced apart along the left-right direction X and extending from the front side 512 away from the rear side 511, and forms two extension wall surfaces 63 respectively formed on the side of the first extension wall 61 and the second extension wall 62 opposite to the base wall 51. The first protruding rib 524 is close to the first extension wall 61 along the left-right direction X.

[0030] Since the extension group 6 and the substrate 5 are integrally injection molded in this embodiment, the material deformation during the stamping process can be prevented by directly shaping the material using a mold through injection molding. This prevents the rear side 511 of the substrate 5 from having corresponding protrusions or depressions, resulting in better flatness and a more aesthetically pleasing appearance.

[0031] The first extension wall 61 has a first inner wall surface 611 facing the needle-receiving space 40, a first groove 612 extending recessed from the corresponding extension wall surface 63 toward the front side surface 512, a first protrusion 613 adjacent to the corresponding extension wall surface 63 and facing the needle-receiving space 40, a first notch 614 opening downward and spaced apart from the first groove 612 along the vertical direction Z, and two grooves 615 respectively adjacent to two opposite ends of the first protrusion 613 along the vertical direction Z. In this embodiment, the first protrusion 613 and the grooves 615 are formed on the first inner wall surface 611, and the first protrusion 613 and the grooves 615 are away from the groove portion 52 along the front-rear direction Y.

[0032] The second extension wall 62 is located to the right of the first extension wall 61 and has a second inner wall surface 621 facing the needle-receiving space 40, a second groove 622 extending recessed from the corresponding extension wall surface 63 toward the front side surface 512, a second protrusion 623 facing the needle-receiving space 40 and close to the groove portion 52, a second notch 624 opening downward and spaced apart from the second groove 622 along the vertical direction Z, a protruding ridge 625 facing the needle-receiving space 40 and moving away from the groove portion 52 along the vertical direction Z, and a notch 626 formed on the second inner wall surface 621 and opening toward the needle-receiving space 40. The length of the second groove 622 extending along the vertical direction Z is greater than the length of the first groove 612 extending along the vertical direction Z, the second protrusion 623 is spaced apart from the first protrusion 613 along the vertical direction Z, and the second notch 624 is symmetrically arranged with the first notch 614 along the left-right direction X.

[0033] Each of the extended wall surface 63 is spaced apart from the corresponding abutting surface 513 along the front-back direction Y, and is separated from the bottom surface 521 of the groove by a second distance D2 along the front-back direction Y, where D2:D1 is between 8:1 and 4:1, for example, 6:1.

[0034] Thus, by means of the structural design in which the second distance D2 is greater than the first distance D1, compared with the conventional method of using the guide ribs of the cover to guide the pins 9, the first extension wall 61 and the second extension wall 62 of this embodiment can directly achieve the effect of guiding the pins 9 set on the pin rail 3 and making the pins 9 properly positioned. Therefore, this embodiment can indeed save the cost of setting an additional cover.

[0035] Referring to Figures 5, 6, and 11, the guide pin seat 7 is connected to the pin rail 3 and faces the guide pin member 4. In this embodiment, the guide pin seat 7 and the guide pin member 4 cooperate to define a space communicating with the pin receiving space 40 and having a downward-facing nail-driving port 70. The first notch 614 and the second notch 624 of the extension assembly 6 are adjacent to the nail-driving port 70.

[0036] The guide pin seat 7 has a seat body 71 with two opposite sides facing the guide pin 4 and the pin rail 3 respectively along the front-rear direction Y, and a fixing member 72 for connecting the seat body 71 and the pin rail 3. The seat body 71 has two guide pin portions 711 that can be respectively embedded in the first notch 614 and the second notch 624. Each guide pin portion 711 has a guide surface 712 near the nail hole 70. The guide surfaces 712 face the guide pin 4 and are used to guide the pin 9. The fixing member 72 is essentially a locking screw.

[0037] The hammerhead 8 is disposed in the receiving space 20 and is operably movable along the vertical direction Z, and has a top end 81 and a bottom end 82 opposite to the top end 81 along the vertical direction Z. The bottom end 82 is adapted to contact and drive out the nail 9. In this embodiment, the hammerhead 8 is located above the nail hole 70 along the vertical direction Z, and can be driven by the pressure handle 21 to drive one of the nails 9 out of the nail hole 70. Since those skilled in the art can deduce the extended details of the hammerhead 8 and the pressure handle 21 from the above description, they will not be described in detail.

[0038] Referring to Figures 5, 9, 11, and 12, in this embodiment, the user can operate the pressure handle 21 to move the nail-driving plate 8 up and down, causing the bottom end 82 of the nail-driving plate 8 to strike the corresponding nail 9. When the foremost nail 9 is struck by the nail-driving plate 8, the nails 9 located at the rear will sequentially move towards the groove 52 along the front-rear direction Y. The structural design of the first protrusion 613 of the first extension wall 61 helps to guide the rear nails 9, achieving the effect of guiding the pusher. Furthermore, the protrusion 625 of the second extension wall 62 can also guide the nail-driving plate 8, preventing it from shifting along the left-right direction X.

[0039] Referring to Figures 12 to 18, the arrangement relationship between the various types of pins 9 and the guide pins 4 will be explained in sequence below:

[0040] First, referring to Figure 12, the pin 9 is generally U-shaped and has an inverted U-shaped top rod 91 and two pin bodies 92 connected to the left and right ends of the top rod 91 and extending downward. When the pin 9 is a U-shaped pin, the pin 9 contacts the bottom surface 521 of the groove, and the lower edge of the U-shape of the top rod 91 can abut against the inclined surfaces 526 of the second ribs 525. The pin body 92 on the left side of the pin 9 is between the first rib 524 and one of the second ribs 525, while the pin body 92 on the right side is between the other second rib 525 and the right side of the groove circumferential surface 522.

[0041] Next, referring to FIG13, when the pin 9 is a small U-shaped pin, the pin 9 contacts the bottom surface 521 of the groove, and the lower edge of the top rod 91 can abut against the top of the second protruding ribs 525. The nail body 92 on the left is between the first protruding rib 524 and one of the second protruding ribs 525, while the nail body 92 on the right is between the other second protruding rib 525 and the right side surface 522 of the groove.

[0042] Referring again to Figure 14, when the nail 9 is a large U-shaped needle and its width is greater than that of the aforementioned small U-shaped needle, the nail 9 contacts the bottom surface 521 of the groove, the top rod 91 is close to the top surface 523 of the groove, the nail body 92 on the left is between one of the groove side surfaces 522 and the first protruding rib 524, and the nail body 92 on the right is adjacent to the other groove side surface 522.

[0043] Additionally, referring to Figures 15 and 16, when the pin 9 is wider than the aforementioned large U-shaped pin, the top rod 91 of the pin 9 is close to the top surface 523 of the groove, and the pin bodies 92 respectively abut against the abutting surfaces 513. The pin body 92 on the left side is close to the first inner wall surface 611, while the pin body 92 on the right side is close to the second inner wall surface 621 and its bottom end abuts against the second protrusion 623. The first protrusion 613 of the first extension wall 61 can guide the left pin body 92, and the second protrusion 623 of the second extension wall 62 can guide the right pin body 92, further preventing the pin 9 from deviating or rotating in the left-right direction X during the process of being struck by the nail-driving plate 8, resulting in high operational stability.

[0044] Furthermore, the right-angled platform formed by the groove periphery 522 and the abutment surface 513 allows the nail body 92 to be stably supported on the abutment surface 513 without tilting towards the groove bottom surface 521. Therefore, this embodiment can indeed improve the stability of the needle delivery.

[0045] Finally, referring to Figures 17 and 18, in another variation of this embodiment, the guide pin 4 further includes a fitting plate 41 connected to the extension assembly 6. The fitting plate 41 has a fitting wall 411 extending in the left-right direction X and fitted into the first groove 612 and the second groove 622, and a fitting groove 412 formed in the fitting wall 411 and facing the needle receiving space 40. The fitting wall 411 has a first fitting section 413 extending in the left-right direction X and protruding from the guide pin 4, and a second fitting section 414 extending downward from the right side of the first fitting section 413. The fitting groove 412 is formed in the second fitting section 414.

[0046] Accordingly, when the pin 9 is a T-shaped pin, the push rod 91 of the foremost pin 9 can abut forward against the notch 626 of the guide pin 4, and the pin body 92 abuts against the abutment surface 513 on the right side. The bottom surface of the push rod 91 of the other pin 9 adjacent to the foremost pin 9 can abut against the fitting groove 412 (as shown in FIG. 18), while the bottom sides of the push rods 91 of the remaining pins 9 abut against the pin rail 3. The second protrusion 623 of the second extension wall 62 can contact and guide the pin body 92.

[0047] It should be noted that in other embodiments, the pin 9 may omit the top rod 91 and be generally L-shaped, and the nail body 92 of the pin 9 may also abut against the abutting surface 513, without limitation.

[0048] Based on the above description, the advantages of the aforementioned embodiments can be summarized as follows:

[0049] 1. The extension assembly 6 and the substrate 5 are integrally injection molded. Since injection molding directly shapes the material using a mold, it avoids material deformation problems during the stamping process, thereby improving the flatness of the guide pin 4. In addition, through integral injection molding, the right-angled platform formed by each groove peripheral side surface 522 and the corresponding abutment surface 513 generates sufficient abutment area to ensure that the pin 9 can be firmly supported by the abutment surface 513 without tilting towards the groove bottom surface 521, thus achieving the effect of stable pin delivery.

[0050] 2. By using a structural design where the second distance D2 is greater than the first distance D1, compared to the conventional method of using a cover to guide the pins, the first extension wall 61 and the second extension wall 62 of this embodiment can directly guide the pins 9 set on the pin rail 3, thus ensuring the pins 9 are properly positioned. Therefore, this embodiment also saves the cost of additionally setting a cover.

[0051] 3. The first protrusion 613 of the first extension wall 61 and the second protrusion 623 of the second extension wall 62 can guide the nail body 92 of the nail 9, thereby improving the stability of operation. In addition, the protruding ridge 625 of the second extension wall 62 can guide the nailing piece 8, further preventing the nailing piece 8 from deviating in the left-right direction X.

[0052] However, the above description is only an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the patent specification shall still fall within the scope of the patent of the present invention. [Simplified Explanation of the Diagram]

[0053] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: Figure 1 is an exploded perspective view illustrating a conventional nail gun disclosed in Republic of China Patent No. TW202504731A; Figure 2 is a perspective view illustrating a guide member of the conventional nail gun; Figure 3 is a cross-sectional schematic diagram illustrating a nail pin disposed on the guide member of the conventional nail gun; Figure 4 is an exploded perspective view illustrating an embodiment of various nail guns of the present invention; Figure 5 is a cross-sectional view of the embodiment; Figure 6 is a partial exploded perspective view of the embodiment; Figure 7 is an incomplete partial perspective view illustrating a guide member of the embodiment; Figure 8 is an incomplete partial perspective view of Figure 7 viewed from another angle; Figure 9 is a front view of Figure 8; Figure 10 is a cross-sectional view taken along line XX in Figure 9; Figure 11 is an incomplete partial front view illustrating the connection relationship between the guide member, a nail holder, and a guide plate of the embodiment; Figure 12 is a schematic diagram of the engagement of the guide pin and a U-shaped pin in this embodiment; Figure 13 is a schematic diagram of the engagement of the guide pin and a U-shaped pin in this embodiment; Figure 14 is a schematic diagram of the engagement of the guide pin and another U-shaped pin in this embodiment; Figure 15 is a schematic diagram of the engagement of the guide pin and another wider U-shaped pin in this embodiment; Figure 16 is a cross-sectional view taken along line XVI-XVI in Figure 15; Figure 17 is an incomplete partial exploded perspective view illustrating a variation of a T-shaped pin disposed on the guide pin; and Figure 18 is a combined schematic diagram of Figure 17.

Claims

1. A guide pin, suitable for mounting in a housing unit of a variety of nail guns, the guide pin comprising: a base plate including a base wall extending in a vertical direction, and a groove formed in the base wall, the base wall having a flat rear side surface, a front side surface opposite to the rear side surface in a front-rear direction, and two abutment surfaces opposite to the rear side surface in the front-rear direction, the groove being recessed in the front side surface and having a groove bottom surface spaced apart from the abutment surfaces in the front-rear direction, and two groove peripheral side surfaces respectively connected to the left and right sides of the groove bottom surface, each groove peripheral side surface substantially perpendicularly connected to the corresponding abutment surface in the front-rear direction, each abutment surface being spaced apart from the groove bottom surface in the front-rear direction by a first distance (D1); and an extending... The extension assembly is integrally injection molded with the substrate and surrounds the substrate to define a needle-receiving space. The extension assembly includes a first extension wall and a second extension wall spaced apart in a left-right direction and extending from the front side away from the rear side. It has two extension wall surfaces formed on the side of the first extension wall and the second extension wall opposite to the base wall. Each extension wall surface is spaced apart from the corresponding abutment surface in the front-rear direction and spaced apart from the bottom surface of the groove by a second distance (D2) in the front-rear direction. The ratio of D2 to D1 is between 8:1 and 4:

1. The left-right direction is substantially perpendicular to the up-down direction and the front-rear direction.

2. The guide pin as described in claim 1, wherein, The groove portion of the substrate also has a first rib extending along the vertical direction and protruding from the bottom surface of the groove, and the first rib is close to the first extension wall along the horizontal direction.

3. The guide pin as described in claim 2, wherein, The recessed portion of the substrate also has two second ribs that extend along the vertical direction and protrude from the bottom surface of the recess. The second ribs are spaced apart along the left-right direction, and the length of each second rib extending along the vertical direction is less than the length of the first rib extending along the vertical direction.

4. The guide pin as described in claim 1, wherein, The first extension wall of the extension assembly has a first protrusion adjacent to the corresponding extension wall surface and facing the needle space.

5. The guide pin as described in claim 4, wherein, The second extension wall of the extension assembly has a second protrusion facing the needle space and close to the groove.

6. The guide pin as claimed in claim 1 further includes a fitting plate, the first extension wall having a first groove extending recessed from the corresponding extension wall surface toward the front side, the second extension wall having a second groove extending recessed from the corresponding extension wall surface toward the front side, the fitting plate being connected to the extension assembly and having a fitting wall extending in the left-right direction and fitted into the first groove and the second groove, and a fitting groove formed in the fitting wall and facing the pin receiving space.

7. The guide pin as described in claim 6, wherein, The length of the second groove extending in the vertical direction is greater than the length of the first groove extending in the vertical direction.

8. The guide pin as described in claim 1, wherein, The second extension wall has a raised ridge facing the needle space and moving away from the groove in the vertical direction.

9. A plurality of nail guns, comprising: a housing unit surrounding and defining a receiving space; a nail rail disposed in the receiving space and adapted to accommodate a plurality of nails; a nail guide as described in any one of claims 1 to 8, disposed in the receiving space; a nail guide seat connected to the nail rail and facing the nail guide, the nail guide seat cooperating with the nail guide to define a space communicating with the receiving space and having a downward-facing nailing port; and a nailing blade disposed in the receiving space and operably movable in a vertical direction, the nailing blade being positioned above the nailing port in the vertical direction and adapted to drive one of the nails out of the nailing port.

10. The various needle guns as described in claim 9, wherein, The first extension wall of the extension assembly has a first notch adjacent to the nail hole, the second extension wall has a second notch adjacent to the nail hole and disposed opposite to the first notch in the left-right direction, the guide pin seat has two guide pin portions that can be respectively embedded in the first notch and the second notch, and each guide pin portion has a guide surface near the nail hole.

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