CN219762646U

CN219762646U - Rubber coating pulling-on piece and pull head of using thereof

Info

Publication number: CN219762646U
Application number: CN202321160999.7U
Authority: CN
Inventors: 陈昌华
Original assignee: Kee Guangdong Garment Accessories Ltd
Current assignee: Kee Guangdong Garment Accessories Ltd
Priority date: 2023-05-15
Filing date: 2023-05-15
Publication date: 2023-09-29
Anticipated expiration: 2033-05-15

Abstract

An encapsulated pull tab and a pull head applied by the same, comprising a sheet-shaped metal framework; the upper end part of the metal framework is provided with a window, so that the upper end part of the metal framework is provided with an upper connecting arm, a left connecting arm and a right connecting arm which form the window; the first plastic holding part is also included; the device is characterized in that a left positioning part which protrudes and extends along the X axis direction is arranged on a left connecting arm, a right positioning part which protrudes and extends along the X axis direction is arranged on a right connecting arm, and the left positioning part and the right positioning part protrude oppositely or protrude oppositely; the lower end part of the metal framework is provided with a lower positioning part extending in a protruding mode along the Z axis direction, the positions of the left positioning part, the right positioning part and the lower positioning part are arranged in a triangular mode, and the top end faces of the left positioning part, the right positioning part and the lower positioning part are exposed out of the first plastic holding part. The lower end part of the metal framework, the left connecting arm and the right connecting arm of the metal framework are covered by the first plastic holding part, so that the service life of the rubber coating pull tab is prolonged, and the overall aesthetic property and the use touch sense of the pull tab are greatly improved.

Description

Rubber coating pulling-on piece and pull head of using thereof

Technical Field

The utility model relates to the technical field of zippers, in particular to an encapsulated pull tab and a pull head applied to the encapsulated pull tab.

Background

The slide fastener generally includes a pair of fastener tapes and a slider slidably mounted on the fastener tapes, and a slider is generally mounted on the slider for facilitating pulling of the slider by driving the slider to move back and forth to thereby couple or separate the pair of fastener tapes. The common pull tab is divided into a hardware pull tab, a plastic pull tab and a pull wire according to the material, along with the continuous improvement of the manufacturing technology, a composite pull tab also appears, for example, an encapsulated pull tab obtained by performing secondary injection molding encapsulation on the hardware pull tab, for example, a temperature-sensing color-changing pull tab and a zipper head are disclosed in Chinese patent publication No. CN218737556U, and the temperature-sensing color-changing pull tab comprises a pull tab substrate 10 and a pull tab holding body 20 fixed on the pull tab substrate, wherein the pull tab substrate 10 is an integral metal piece, the pull tab substrate 10 comprises a pull tab connecting part 11 and an injection molding frame part 12 extending from one end of the pull tab connecting part 11, a through groove penetrating in the thickness direction is formed in the injection molding frame part 12, and the pull tab holding body 20 is fixed on the injection molding frame part 12 of the pull tab substrate 10 in an injection molding manner.

Disclosure of Invention

Injection molding is carried out on the basis of basic metal pieces, and is commonly called as encapsulation hardware. In the injection molding production of such encapsulated hardware, it is a very important link to reliably position the base metal part within the injection mold. The chinese patent publication No. CN218737556U discloses a temperature-sensitive color-changing tab, in which the entire tab connecting portion is provided as a bare portion, or the tab base is reliably positioned during injection molding, however, as can be seen from fig. 1 disclosed in the publication, the entire tab connecting portion 11 is provided as a bare portion, and the "bare" arrangement is biased toward one end portion of the tab base 10, so that the positioning effect is very general and unsightly.

To this end, the utility model proposes an encapsulated pull tab comprising a sheet-like metal skeleton extending in the X-Y direction and having a thickness in the Z-axis direction, as viewed in the X-Y-Z axis direction, wherein the length extending in the Y-axis direction is greater than the width extending in the X-axis direction, in terms of minimizing "bare" parts and improving the aesthetic appeal, but ensuring even further improved positioning of the mold with respect to the base metal part (e.g., the pull tab body 10 disclosed in the chinese patent publication No. CN 218737556U); the upper end part of the metal framework is provided with a window, so that the upper end part of the metal framework is provided with an upper connecting arm, a left connecting arm and a right connecting arm which form the window; the first plastic holding part is used for covering the metal framework, but at least the middle section part of the upper connecting arm is not covered; the left connecting arm is provided with a left positioning part extending in a protruding mode along the X axis direction, the right connecting arm is provided with a right positioning part extending in a protruding mode along the X axis direction, and the left positioning part and the right positioning part protrude oppositely or protrude oppositely; the lower end part of the metal framework is provided with a lower positioning part extending in a protruding mode along the Z axis direction, the positions of the left positioning part, the right positioning part and the lower positioning part are arranged in a triangular mode, and the top end faces of the left positioning part, the right positioning part and the lower positioning part are exposed out of the first plastic holding part.

The metal framework is a supporting body of the rubber coating pull tab, is a member for ensuring the strength of the whole structure of the rubber coating pull tab, and in order to facilitate the description of the structure of the metal framework, the direction of an X-Y-Z three-dimensional coordinate axis is defined to specify the direction of a sheet structure, and the metal framework is a strip-shaped structure extending along the X-Y direction as seen along the Z direction (i.e. overlooking direction), wherein the X direction is a width direction, the Y direction is a length direction, and the Z direction is a height direction of the metal framework.

The window is a through hole structure arranged at the upper end part of the metal framework, and the encapsulation pull tab can be connected with a latch hook mentioned below through the window. And the upper connecting wall extending along the X direction, the left connecting arm, the right connecting arm and the lower end part of the metal framework extending along the Y direction are arranged around the window.

The upper connecting arm is a rod-shaped member positioned at the upper end of the metal framework, the whole or at least the middle section part of the upper connecting arm is not coated with plastic, the upper and lower mold cores of the mold tightly wrap the outer surface of the upper connecting arm during secondary injection molding, and the upper connecting arm has a limiting effect in the Y-axis direction and the Z-axis direction.

The first plastic holding part covers the metal framework but at least the middle section part of the upper connecting arm is not covered, which means that the first plastic holding part can entirely expose (not cover) the upper connecting arm from the maximum exposed range of the upper connecting arm; from the minimum exposure range, the first plastic holding part can only expose the middle section part of the upper connecting arm, the middle section part is not covered, or the first plastic holding part covers a certain numerical point of the upper connecting arm in a range between the two limit ranges.

The first plastic holding part is a plastic component coated on the metal framework through injection molding, and is also one of main parts of the rubber-coated pull tab held by the hand, so as to improve the holding comfort.

The left connecting arm is provided with a left positioning part extending in a protruding mode along the X axis direction, the main protruding direction of the left positioning part is defined, the left positioning part is not equal to the fact that the left positioning part only protrudes along the X axis direction to have a protruding height, the left connecting arm actually has a certain proper protruding width in the Y axis direction and a certain proper protruding thickness in the Z axis direction based on the limitation of text expression, and the left positioning part is of a three-dimensional protruding structure. Similarly, the right positioning part and the lower positioning part are three-dimensional stereo convex structures.

The left positioning part and the right positioning part are protruded in opposite directions or protruded in opposite directions, and concretely comprise the following two arrangement modes, wherein the first two arrangement modes are that the left positioning part and the right positioning part are protruded in opposite directions and extend into the window, and a gap for a die to enter is reserved between top end surfaces of the opposite arrangement of the left positioning part and the right positioning part; second, left side location portion, right location portion are opposite to the outside both sides protrusion of rubber coating pulling-on piece, specifically, left side location portion set up in left side of left linking arm and extend to the left, right side location portion set up in right side of right linking arm and extend to the right. The effect achieved by both embodiments is substantially the same, both limiting the displacement of the encapsulated pull tab in the X direction, wherein the first arrangement is preferred because of the certain concealment of the exposed face.

The lower positioning part is arranged along the Z-axis direction in an extending mode and protrudes out of the lower end portion of the metal framework, one side or two sides of the lower end portion of the metal framework protrude out, and displacement of the metal framework in the Z-axis direction during secondary injection molding can be limited through the lower positioning part. Further, the shape of the lower positioning part is words, patterns, and the words and the patterns can be used as LOGO when seen along the Z axis direction.

According to the technical scheme, compared with the prior art, the utility model has the beneficial technical effects that: firstly, the lower end part of the metal framework, the left connecting arm and the right connecting arm of the metal framework are covered by the first plastic holding part, the upper connecting arm is exposed out of the slider main body of the connecting pull head, so that softer plastic covers the metal framework as much as possible, and the wear-resistant metal parts are used for connection, so that the service life of the rubber-coated pull piece can be prolonged, and the overall aesthetic property and the use touch of the pull piece can be greatly improved; secondly, although the exposed area and the range of the metal framework are greatly reduced, the metal framework can realize the positioning in the Y axis direction through the upper connecting arm, the positioning in the X axis direction is realized through the left positioning part and the right positioning part, and the positioning in the Z axis direction is realized through the lower positioning part, so that the three-dimensional positioning structure is quite stable, the position stability of the metal framework during secondary injection molding is ensured, and the encapsulation quality of the encapsulation pull tab is greatly improved; third, go up linking arm, left location portion, right location portion and lower location portion top-down interval arrangement, go up linking arm and lower location portion upper and lower interval centre gripping metal skeleton, left side location portion, right location portion and lower location portion's position is triangle-shaped and arranges, has effectively solved the problem that metal skeleton overturns when the secondary is moulded plastics, has further improved metal skeleton's position stability when carrying out the secondary and moulding plastics.

Further technical scheme can be that left location portion, right location portion are the frustum form, the tip terminal surface of left location portion, right location portion is the tip terminal surface of frustum. The left positioning part and the right positioning part which are arranged in the way not only ensure the positioning in the X direction, but also reduce the exposure of the end surface as much as possible, thereby being beneficial to improving the aesthetic property of the rubber coating pull tab after secondary injection molding.

Further technical scheme may be that the upper connecting arm is further provided with an upper step protruding along the Z axis direction, and a step surface of the upper step is flush with a top end surface of the lower positioning portion. In a specific embodiment, the upper step protrudes to one side or two sides along the Z axis, so that the step surface of the upper step is flush with the top end surface of the lower positioning portion, and the metal framework can be stably placed in the injection mold.

Further, the outer surface of the first plastic holding part is substantially flush with the top end surfaces of the left positioning part, the right positioning part and the lower positioning part, and the step surface of the upper connecting arm. This contributes to the overall aesthetic appearance of the encapsulated pull tab.

The lower end part of the metal framework is further provided with a rubber column through hole, and the rubber column through hole extends along the Z-axis direction and penetrates through the lower end part of the metal framework. When carrying out the secondary and moulding plastics, thereby the plastic of first plastic gripping portion can fill the glue post through-hole cladding in thereby the plastic of metal skeleton lower tip both sides links together, is favorable to improving the joint strength of first plastic gripping portion and metal skeleton.

Further technical scheme can be that the lower tip of first plastic portion of gripping sets up and is the joint portion of T shape be provided with the joint hole on the joint portion, still include second plastic portion of gripping, second plastic portion of gripping pass through the joint portion connect in on the first plastic portion of gripping.

Because the rubber coating pulling piece has above advantage, so can be applied to the pull head, including slider main part, latch hook and lid, including upper plate and the hypoplastron of interval arrangement on the slider main part, form the tooth passageway between upper plate and the hypoplastron be provided with the hook hole on the upper plate, the link swing joint of latch hook in the upper plate, the lid connect in the upper plate and lid close on the latch hook, still include the rubber coating pulling piece, metal skeleton's upper connecting arm arrange in between upper plate and the latch hook, the locking end of latch hook can pass the window of metal skeleton upper end and go into hook hole on the upper plate and insert in the tooth passageway, through the pulling rubber coating pulling piece can drive the locking end of latch hook is kept away and is moved the tooth passageway.

Because of the above features and advantages, the present utility model may be used in encapsulated tabs and in sliders for use therewith.

Drawings

FIG. 1 is a schematic view of the axial side structure of the slider;

FIG. 2 is a schematic view of an exploded construction of the slider;

FIG. 3 is a schematic axial side structural view of the encapsulated pull tab;

FIG. 4 is a schematic top view of the encapsulated pull tab;

FIG. 5 is a schematic view of the cross-sectional structure in the direction A-A in FIG. 4;

FIG. 6 is a schematic view of an axial side direction structure of the metal skeleton;

FIG. 7 is a schematic view of the axial structure of the first plastic grip;

FIG. 8 is a schematic view of an exploded construction of the encapsulated pull tab;

FIG. 9 is a schematic view of an axial structure of the metal skeleton, showing a second arrangement of the left positioning portion and the right positioning portion;

fig. 10 is a schematic axial structure view of the first plastic holding portion covering the metal frame, showing that the middle section of the upper connecting arm is not covered.

Description of the embodiments

The structure of the encapsulated pull tab and the pull head using the same according to the technical scheme of the present utility model will be further described with reference to the accompanying drawings.

The various implementation details disclosed below may be applied either selectively or in combination in one embodiment, even without direct functional association or co-ordination, except where explicitly stated to be equivalent or alternative embodiments.

As shown in fig. 1 and 2, the slider comprises a slider body 1, a latch hook 2 and a cover 3, wherein the slider body 1 comprises an upper plate 11 and a lower plate 12 which are arranged at intervals, a fastener tooth channel 10 is formed between the upper plate 11 and the lower plate 12, a hook hole is formed in the upper plate 11, the connecting end of the latch hook 2 is movably connected with the upper plate 11, the cover 3 is connected with the upper plate 11 and covers the latch hook 2, the slider further comprises a rubber coating pull piece 4, the rubber coating pull piece 4 is connected between the upper plate 11 and the latch hook 2, and the locking end of the latch hook 2 can pass through the connecting hole of the rubber coating pull piece 4 and the hook hole in the upper plate 11 and is inserted into the fastener tooth channel 10, and the locking end of the latch hook 2 can be driven to be separated from the fastener tooth channel 10 by pulling the rubber coating pull piece 4.

The structure of the encapsulation tab 4 will be described in detail below, the encapsulation tab 4 including a sheet-shaped metal skeleton 5, the metal skeleton 5 extending in the X-Y direction, wherein the length extending in the Y-axis direction is greater than the width extending in the X-axis direction; the upper end of the metal frame 5 has a window 50 such that the upper end of the metal frame 5 has an upper connecting arm 51, a left connecting arm 52, a right connecting arm 53 constituting the window 50; the first plastic holding part 6 is covered on the metal framework 5, but at least the middle section part of the upper connecting arm 51 is not covered, namely, the first plastic holding part 6 can entirely expose (not cover) the upper connecting arm 51 from the maximum exposed range of the upper connecting arm 51; only the middle portion of the upper link arm 51 is exposed to the minimum extent of exposure without being covered or at a point between these two limits. The middle section is the central area of the upper connecting arm 51, and mainly directly contacts and connects with the latch hook 2. Compared with the prior art, the metal framework 5 greatly reduces the exposed area and range; a left positioning portion 521 extending in a protruding manner along the X axis direction is provided on the left connecting arm 52, a right positioning portion 531 extending in a protruding manner along the X axis direction is provided on the right connecting arm 53, and the left positioning portion 521 and the right positioning portion 531 protrude in opposite directions or protrude in opposite directions; the lower end portion of the metal skeleton 5 is provided with a lower positioning portion 54 extending in a protruding manner along the Z-axis direction, the positions of the left positioning portion 521, the right positioning portion 531 and the lower positioning portion 54 are arranged in a triangle, and the top end surfaces of the left positioning portion 521, the right positioning portion 531 and the lower positioning portion 54 are exposed from the first plastic holding portion 6. The areas where the top end surfaces of the left positioning portion 521, the right positioning portion 531, and the lower positioning portion 54 are exposed are very small and can be almost ignored.

As shown in fig. 3 and 4, XYZ axis directions are axis directions of three-dimensional coordinates arranged perpendicular to each other, and are set so as to better explain the above-mentioned wrapping tab 4, and three axis directions also correspond to directions in the description one by one, wherein X axis directions correspond to a left-right direction (also a width direction), Y axis directions correspond to an up-down direction (also a length direction), and Z axis directions correspond to a front-back direction (also a thickness direction). A schematic view of the over-the-air tab 4 in a top view is shown in fig. 4, which can also be understood as a view looking in the Z-axis direction. The length of the metal skeleton 5 extending in the Y axis direction is longer than the width of the metal skeleton extending in the X axis direction, which means that the metal skeleton 5 has a vertically elongated structure.

The window 50 is a through hole structure disposed at the upper end of the metal frame 5, and the encapsulating tab 4 can be connected to the latch hook 2 through the window 50, as shown in fig. 3, the window 50 is disposed extending along the Z-axis direction and penetrating through the metal frame 5. The first plastic holding portion 6 covers the metal frame 5, that is, the first plastic holding portion 6 covers the lower end portion of the metal frame 5 and the left and right connecting arms 52 and 53 of the metal frame 5, but at least the middle section of the upper connecting arm 51 made of metal is exposed and not covered by the first plastic holding portion 6, which is advantageous in that, on one hand, the first plastic holding portion 6 covers the metal frame 5 as much as possible to improve the overall aesthetic property and the comfort of the pull tab; on the other hand, the wear-resistant metal part is connected with the sliding block main body 1 and the lock hook 2, so that the service life of the rubber coating pull tab is effectively prolonged.

The left positioning portion 521 and the right positioning portion 531 protrude toward each other or protrude away from each other, which specifically includes the following two arrangements:

in the first arrangement, as shown in fig. 6, the left positioning portion 521 is disposed on the right side of the left connecting arm 52 and extends to protrude rightward, the right positioning portion 531 is disposed on the left side of the right connecting arm 53 and extends to protrude leftward, the left positioning portion 521 and the right positioning portion 531 protrude toward each other and extend into the window 50, and a gap is left between the oppositely disposed top end surfaces of the left positioning portion 521 and the right positioning portion 531 so as to be able to combine with the mold to form positioning. In this arrangement, the left positioning portion 521 is used to restrict the metal frame 5 from moving leftwards, and the right positioning portion 531 is used to restrict the metal frame 5 from moving rightwards.

In the second arrangement, as shown in fig. 9, the left positioning portion 521 'is disposed on the left side of the left connecting arm 52 and extends leftward, the right positioning portion 531' is disposed on the right side of the right connecting arm 53 and extends rightward, and the left positioning portion 521 'and the right positioning portion 531' are formed in a state of being opposite to each other and protrude toward both sides of the outside of the over-coating tab 4. In this arrangement, the left positioning portion 521 'is used to restrict the movement of the metal frame 5 to the right, and the right positioning portion 531' is used to restrict the movement of the metal frame 5 to the left.

The effect achieved by both embodiments is substantially the same, both limiting the displacement of the encapsulated pull tab 4 in the X direction, but the first is preferably used to reduce the exposure of metal parts.

The lower positioning portion 54 is configured to extend along the Z-axis and protrude from the lower end portion of the metal skeleton 5, and may protrude from one side or both sides of the lower end portion of the metal skeleton 5, and displacement of the metal skeleton 5 in the Z-direction during secondary injection molding can be limited by the lower positioning portion 54, as shown in fig. 3 to 5, and the configuration with protruding sides is selected to be more stable. Further, the shape of the lower positioning portion 54 is text, pattern, text and pattern, as seen along the Z-axis direction, which can be used as LOGO.

From the above, the metal skeleton 5 is positioned in the Y axis direction by the upper connecting arm 51, positioned in the X axis direction by the left positioning portion 521 and the right positioning portion 531, and positioned in the Z axis direction by the lower positioning portion 54, and the positioning structure is very stable. In addition, the upper connecting arm 51, the left positioning portion 521, the right positioning portion 531 and the lower positioning portion 54 are arranged at intervals from top to bottom, the upper connecting arm 51 and the lower positioning portion 54 can clamp the metal framework 5 in the Z-axis direction, and the positions of the left positioning portion 521, the right positioning portion 531 and the lower positioning portion 54 are arranged in a triangle, so that the problem that the metal framework 5 overturns during secondary injection molding is well solved, the position stability of the metal framework 5 during secondary injection molding is ensured, and the encapsulation quality of the encapsulation pull piece 4 is greatly improved.

Further, as shown in fig. 6 to 9, the left positioning portion 521 and the right positioning portion 531 are in a frustum shape, and the top end surfaces of the left positioning portion 521 and the right positioning portion 531 are small end surfaces of the frustum. The left positioning portion 521 and the right positioning portion 531 thus arranged can not only realize positioning in the X direction, but also reduce the exposure of the metal end surface as much as possible, which is beneficial to improving the aesthetic property of the encapsulated pull tab 4 after secondary injection molding.

Further, as shown in fig. 6 to 9, the upper connecting arm 51 is further provided with an upper step 511 protruding in the Z-axis direction, and the step surface of the upper step 511 is flush with the top surface of the lower positioning portion 54. This allows the step surface of the upper step 511 to be flush with the tip surface of the lower positioning portion 54, enabling the metal bobbin 5 to be placed in an injection mold smoothly. After the secondary injection molding is completed, the outer surface of the first plastic holding part 6 is substantially flush with the top end surfaces of the left positioning part 521, the right positioning part 531 and the lower positioning part 54, and the step surface of the upper connecting arm 51. This greatly improves the overall aesthetics of the encapsulated pull tab 4.

Further, as shown in fig. 6 and 8, a glue post through hole 55 is further provided at the lower end of the metal frame 5, and the glue post through hole 55 extends along the Z axis direction and penetrates through the lower end of the metal frame 5. When the secondary injection molding is performed, the plastic of the first plastic holding part 6 can fill the plastic column through holes 55 so as to connect the plastic coated on two sides of the lower end part of the metal framework 5 together, which is beneficial to improving the connection strength of the first plastic holding part 6 and the metal framework 5.

Further, as shown in fig. 7 and 8, the lower end portion of the first plastic holding portion 6 is provided with a T-shaped coupling portion 61, the coupling portion 61 is provided with a clamping hole 62, and the second plastic holding portion 7 is further included, and the second plastic holding portion 7 is connected to the first plastic holding portion 6 through the coupling portion 61. By arranging the second plastic holding part 7, the encapsulated pull tab 4 can realize multicolor collocation, and the holding comfort of the encapsulated pull tab 4 can be improved by using plastics with different hardness.

Claims

1. An encapsulated pull tab comprising a metal skeleton in the form of a sheet, the metal skeleton extending in an X-Y-Z direction and having a thickness in a Z-axis direction, as viewed in the X-Y-Z direction, wherein the length extending in the Y-axis direction is greater than the width extending in the X-axis direction; the upper end part of the metal framework is provided with a window, so that the upper end part of the metal framework is provided with an upper connecting arm, a left connecting arm and a right connecting arm which form the window; the first plastic holding part is used for covering the metal framework, but at least the middle section part of the upper connecting arm is not covered; the left connecting arm is provided with a left positioning part which protrudes and extends along the X axis direction, the right connecting arm is provided with a right positioning part which protrudes and extends along the X axis direction, and the left positioning part and the right positioning part protrude oppositely or protrude back to back; the lower end part of the metal framework is provided with a lower positioning part extending in a protruding mode along the Z axis direction, the positions of the left positioning part, the right positioning part and the lower positioning part are arranged in a triangular mode, and the top end faces of the left positioning part, the right positioning part and the lower positioning part are exposed out of the first plastic holding part.

2. The encapsulated pull tab of claim 1 wherein the left and right locating portions are frustoconical and the top end surfaces of the left and right locating portions are the small end surfaces of the frustoconical.

3. The encapsulated pull tab of claim 2 wherein the upper connecting arm is further provided with an upper step projecting in the Z-axis direction, the step surface of the upper step being flush with the top end surface of the lower locating portion.

4. The overmolded pull tab of claim 3 wherein the outer surface of the first plastic gripping portion is substantially flush with the top surfaces of the left and right and lower positioning portions and the stepped surface of the upper connecting arm.

5. The encapsulated pull tab of any one of claims 1-4, wherein a post through hole is further provided at a lower end of the metal skeleton, the post through hole extending along the Z-axis direction and penetrating through the lower end of the metal skeleton.

6. The overmolded pull tab of claim 5 wherein the lower positioning portion is shaped as a letter or pattern as viewed along the Z-axis.

7. The encapsulated pull tab of claim 5, wherein the lower end of the first plastic grip is provided with a T-shaped coupling portion having a clamping hole, and further comprising a second plastic grip connected to the first plastic grip by the coupling portion.

8. The utility model provides a pull head, includes slider main part, latch hook and lid, including upper plate and the hypoplastron of interval arrangement on the slider main part, form the chain tooth passageway between upper plate and the hypoplastron be provided with the hook hole on the upper plate, the link swing joint of latch hook in the upper plate, the lid connect in the upper plate and lid closes on the latch hook, its characterized in that still includes any one of claim 1~7 the rubber coating pulling-on piece, metal skeleton's upper connecting arm arrange in between upper plate and the latch hook, the locking end of latch hook can pass the window of metal skeleton upper end and the hook hole on the upper plate is inserted in the chain tooth passageway, through pulling the rubber coating pulling-on piece can drive the locking end of latch hook is from moving the chain tooth passageway.