Fiber composite material watch case, watch, and manufacturing method of watch case

Abstract

The invention discloses a fiber composite material watch case, a watch and a method for making the watch case, the method comprising: making an inner liner with a cavity extending through from top to bottom from a heat-resistant polymer material by injection molding; loading the inner liner into a fiber composite material forming mold, filling a fiber prepreg in a mold cavity between the outer side of the inner liner and the mold, pressing and molding under a preset temperature and a preset pressure for a preset time, and demolding after cooling to form a watch case blank consisting of a heat-resistant polymer material inner liner and a fiber composite material outer shell. The invention can not only reduce the weight of the watch, but also improve the bonding strength between the inner liner and the fiber composite material and reduce the inconsistency of thermal expansion; moreover, through the technology combining efficient and low-cost injection molding and molding, a waterproof structure is realized by the inner liner, and the outer fiber composite material realizes the appearance effect and the functions of wear resistance, corrosion resistance and aging resistance, and can be mass-produced.

Description

Technical Field

[0001] The invention relates to the field of watches, and in particular to a fiber composite material watch case, a watch and a manufacturing method of the watch case. Background Art

[0002] Fiber composite materials are composite materials formed by matrix materials and carbon fiber, glass fiber, metal fiber, ceramic fiber, etc., in which the matrix is ​​mainly epoxy resin. The specific modulus and specific strength of fiber composite materials are higher than those of steel, aluminum, and titanium, and they have good performance in wear resistance and pressure resistance. By adjusting the process, rich patterns and unique textures can also be presented. Although fiber composite materials have the above-mentioned excellent properties, the fibers will separate the matrix of the composite materials, so the fiber composite materials themselves are not dense enough and cannot play a waterproof role under pressure. When fiber composite materials are used as watch cases, they must withstand at least 30m water depth pressure. Failure of waterproofing will cause sweat to penetrate into the movement and corrode the movement.

[0003] In the prior art, fiber composite watch cases are made by adding a metal, ceramic or alloy liner to the inner layer of the fiber composite material, relying on a fully dense liner to isolate the movement from sweat and achieve a waterproof effect. The metal or alloy used as the liner is required to have high corrosion resistance. The materials used in the prior art are mainly stainless steel, but the density of stainless steel is close to 8 grams per cubic centimeter, which is much higher than the density of fiber composite materials of about 1 gram per cubic centimeter, causing the watch to partially lose the weight reduction effect brought by the use of fiber materials, affecting the wearing experience. There is also technology that uses industrial pure titanium or titanium alloy with a density of 4 to 5 grams per cubic centimeter as the liner, but the weight reduction effect is still limited.

[0004] In addition, in the prior art, the preparation of fiber composite parts requires precise pressing of the fiber composite material and the inner liner. During the pressing process, the inner liner will be subjected to high pressure and high temperature. In Patent ZL201720398044.3, the metal or alloy inner liner blank is first processed, and then the metal or alloy inner liner blank is placed in a mold, and then the carbon fiber composite material raw material is added to the mold, and then pressure and high temperature are applied to make the inner liner and the carbon fiber composite material tightly combined. Due to the poor affinity between metal or alloy and carbon fiber composite materials, the thermal expansion coefficients are greatly different. When the case is subjected to hot and cold shocks, the inconsistent expansion can easily cause the connection between the inner liner and the carbon fiber shell to loosen or crack. Patent application 201910422125.6 discloses an external component made of composite materials and a method for manufacturing the external component, wherein a reinforcement is made by additive manufacturing, and then the reinforcement is embedded in a synthetic material, wherein the reinforcement is a perforated structure, and the synthetic material is selected from fluorinated elastomers (FK, FFKM), polyurethane elastomers (PUR), polysiloxanes, thermoplastic elastomers (TPE) or thermosetting resins. When used as a watch, the inner layer reinforcement can only play a role in structural reinforcement due to its through-hole structure, and the outer layer synthetic material plays a waterproof role. However, it is well known that the above-mentioned synthetic materials are poor in color, wear resistance, strength, aging performance, etc. At the same time, the technical solution is made of reinforcements by additive manufacturing, which is inefficient and costly, and is not suitable for large-scale mass production. Summary of the invention

[0005] The technical problem to be solved by the present invention is that, in view of the above-mentioned defects of the prior art, in order to reduce the weight of the watch, simplify the preparation process of the watch case, improve the bonding strength between the liner and the fiber composite material, and improve the resistance to cold and hot shocks, a fiber composite material watch case, a watch and a method for making the watch case are provided.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] On the one hand, a method for manufacturing a watch case is constructed, the method comprising:

[0008] The heat-resistant polymer material is made into an inner container having a cavity that passes through from top to bottom by injection molding;

[0009] The inner liner is loaded into a fiber composite material forming mold, and the fiber prepreg is filled in the cavity between the outer side of the inner liner and the mold. The inner liner is pressed and formed at a preset temperature and a preset pressure for a preset time, and the mold is demolded after cooling to form a watch case blank consisting of a heat-resistant polymer material inner liner and a fiber composite material outer shell.

[0010] Preferably, the preset temperature is 150-160° C., the preset pressure is 20-200 MPa, and the preset time is 1-30 s.

[0011] Preferably, the heat-resistant polymer material is a polymer material that can withstand temperatures of 160° C. or above.

[0012] Preferably, the heat-resistant polymer material is PEK or PEEK or PPS.

[0013] Preferably, the fibers in the fiber composite material include one or more of carbon fibers, glass fibers, metal fibers, and ceramic fibers.

[0014] Preferably, the fiber composite material is a fiber epoxy resin composite material.

[0015] On the other hand, a fiber composite material watch case is constructed, which includes an inner liner injection-molded from a heat-resistant polymer material and a fiber composite material outer shell formed by attaching fiber prepreg to the outer side of the inner liner by molding.

[0016] On the other hand, a fiber composite material watch is constructed, including a bottom cover, a watch case, a movement and a dial assembly, wherein the watch case is provided with a cavity which passes through from top to bottom, the dial assembly and the bottom cover are respectively assembled with the upper and lower parts of the watch case and seal the cavity, the movement is arranged in the cavity, and the watch case includes an inner liner injection-molded from a heat-resistant polymer material and a fiber composite material outer shell formed by attaching fiber prepreg to the outer side of the inner liner by molding.

[0017] Preferably, at least one reinforcing connection structure for increasing the bonding strength between the inner liner and the fiber composite material is provided on the outer side of the inner liner.

[0018] Preferably, the reinforcing connection structure is a groove and / or a convex structure;

[0019] Preferably, the dial assembly includes an inner shadow ring, a dial, and a watch glass. The bottom cover is connected to the lower part of the watch case, and a first sealing ring is provided at the joint between the bottom cover and the watch case. The watch glass is pressed onto the upper part of the watch case through a second sealing ring. The inner shadow ring, the dial, and the movement are arranged in the cavity. The inner side of the inner tank is provided with a first boss for carrying the dial and a second boss for carrying the movement. The movement is located below the dial. The inner shadow ring is installed on the dial and below the watch glass. The inner side of the inner tank has an annular sealing groove for accommodating the first sealing ring at a position near the bottom, and the inner side of the inner tank is processed to form an annular groove at a position near the upper part to provide a deformation space for the second sealing ring.

[0020] Preferably, the watch case is provided with a handlebar mounting hole for mounting the handlebar, the handlebar is interference-fitted or glued to the handlebar mounting hole, a handle is inserted into the handlebar, a third sealing ring and a fourth sealing ring are respectively installed between the inner side of the handlebar and the handlebar, and between the outer side of the handlebar and the handlebar.

[0021] An annular groove for accommodating the third sealing ring is provided on the portion of the handle that is sleeved on the inner side of the handle tube; a boss is provided on the portion of the handle that is sleeved on the outer side of the handle tube, and an annular metal limiting plate is also sleeved on the outer side of the handle tube, and the fourth sealing ring is clamped between the metal limiting plate and the boss, and the metal limiting plate and the handle have an interference fit to prevent the sealing ring from detaching when the handle is pulled out.

[0022] The fiber composite material watch case, watch and method for making the watch case of the present invention have the following beneficial effects: the inner liner of the watch case of the present invention is injection molded from a heat-resistant polymer material, and a fiber prepreg is attached to the outer side of the inner liner by molding to form a fiber composite material outer shell, which not only reduces the weight of the watch, but also improves the bonding strength between the inner liner and the fiber composite material and reduces the inconsistency of thermal expansion; moreover, through the combination of efficient and low-cost injection molding and molding technology, a waterproof structure is achieved through the inner liner, and the outer fiber composite material achieves an appearance effect and wear-resistant, corrosion-resistant and anti-aging functions, which can be mass-produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without creative work:

[0024] Figure 1 is a schematic diagram of the structure of the watch of the present invention from different viewing angles;

[0025] Figure 2 is a cross-sectional view of the watch of the present invention;

[0026] Figure 3 It is a cross-section of the case;

[0027] Figure 4 This is the assembly diagram of the. DETAILED DESCRIPTION

[0028] In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Typical embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0029] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time. The terms "upper", "lower", "inner", "outer" and similar directional expressions used herein are for illustrative purposes only.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0031] Terms including ordinal numbers such as "first", "second" etc. used in this specification may be used to describe various constituent elements, but these constituent elements are not limited by these terms. The purpose of using these terms is only to distinguish one constituent element from other constituent elements. For example, without departing from the scope of the present invention, the first constituent element may be named as the second constituent element, and similarly, the second constituent element may also be named as the first constituent element. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0032] The general idea of ​​the present invention is: an inner liner with a cavity running through from top to bottom is made of a heat-resistant polymer material through injection molding, the inner liner is then loaded into a fiber composite material forming mold, fiber prepreg is filled in the cavity between the outer side of the inner liner and the mold, and the inner liner is pressed and formed at a preset temperature and a preset pressure for a preset time, and the outer liner is demolded after cooling to form a watch case blank composed of a heat-resistant polymer material inner liner and a fiber composite material outer shell, after which the watch case blank can be precision machined.

[0033] In order to better understand the above-mentioned technical scheme, the above-mentioned technical scheme will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical scheme of the present application, rather than limitations on the technical scheme of the present application. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0034] refer to Figure 1-2 The fiber composite material watch of the present invention comprises a bottom cover 1, a watch case 2, a movement 4 and a dial assembly 3. The watch case 2 is provided with a cavity which passes through from top to bottom. The dial assembly 3 and the bottom cover 1 are respectively assembled with the upper and lower parts of the watch case 2 and seal the cavity. The movement 4 is arranged in the cavity.

[0035] The watch case 2 of the present invention comprises an inner liner 21 formed by injection molding of a heat-resistant polymer material and a fiber composite material outer shell 22 formed by attaching fiber prepreg to the outer side of the inner liner 21 by molding.

[0036] Specifically, the present invention also provides a method for manufacturing the watch case 2, the method comprising:

[0037] S101: Forming an inner container 21 having a vertically penetrating cavity from a heat-resistant polymer material by injection molding;

[0038] Among them, the heat-resistant polymer material is recommended to be a polymer material that can withstand temperatures of 160° C. and above, such as PEK or PEEK or PPS, etc., preferably PEEK.

[0039] S102: Load the inner liner 21 into a fiber composite material forming mold, fill the fiber prepreg in the cavity between the outer side of the inner liner 21 and the mold, press and form at a preset temperature and preset pressure for a preset time, and demold after cooling to form a watch case blank composed of a heat-resistant polymer material inner liner 21 and a fiber composite material outer shell 22.

[0040] Wherein, the preset temperature is 150-160° C., the preset pressure is 20-200 MPa, and the preset time is 1-30 s.

[0041] Wherein, the fiber composite material is a fiber epoxy resin composite material. The fibers in the fiber composite material include one or more of carbon fiber, glass fiber, metal fiber and ceramic fiber.

[0042] Several specific embodiments of the present invention are described in detail below.

[0043] Embodiment 1

[0044] like Figure 1-2 The watch includes a case 2, a dial assembly 3, a movement 4, a handle 6, a handle 5, first to fourth sealing rings 71-74, etc. The dial assembly 3 includes an inner ring 32, a dial 31, a watch glass 33, and a watch hand 34.

[0045] The case 2 is provided with a cavity, the bottom cover 1 is connected to the lower part of the case 2, and a first sealing ring 71 is provided at the joint between the bottom cover 1 and the case 2. It can be understood that the bottom cover 1 can be pressed on the lower part of the inner liner 21 of the case 2, or connected to the inner liner 21 by threads or screws. The watch glass 33 is pressed on the upper part of the case 2 by the second sealing ring 72, and the inner ring 32, the dial 31, and the movement 4 are arranged in the cavity.

[0046] The dial 31 and the movement 4 are fixed in the cavity of the watch case 2 by screws. Specifically, the inner side of the inner tank 21 is provided with a first boss 214 for carrying the dial 31 and a second boss 215 for carrying the movement 4. The dial 31 and the movement 4 are respectively hung on the corresponding first boss 214 and second boss 215 and fixed to the first boss 214 and second boss 215 by screws. The movement 4 is located in the cavity and below the dial 31. The movement 4 and the dial 31 are fastened by screws. The inner shadow ring 32 is installed on the dial 31. The inner shadow ring 32 is located below the watch glass 33 and abuts against the watch glass 33 from top to bottom. The movement 4 axis passes through the dial 31 hole, and the watch hand 34 is located on the upper part of the dial 31 and fixed on the movement 4 axis (not shown). In this embodiment, the movement 4 is a mechanical or quartz movement. In other embodiments, the movement 4 can also be a smart watch movement.

[0047] refer to Figure 3 Preferably, the inner side of the inner liner 21 has an annular sealing groove 211 at the bottom for accommodating the first sealing ring 71. The inner side of the inner liner 21 has an annular groove 212 at the upper part for providing a deformation space for the second sealing ring 72. The cross section of the annular groove 212 is preferably wedge-shaped. In this embodiment, after the watch case blank is formed by demolding after cooling, only the annular groove 212 needs to be machined, and the other structures of the watch case 2 are formed during injection molding and molding.

[0048] Preferably, at least one reinforcing connection structure 213 is provided on the outer side of the inner liner 21 for increasing the bonding strength between the inner liner 21 and the fiber composite material shell 22. The reinforcing connection structure 213 is a groove and / or a protrusion structure. Figure 3 In this embodiment, the outer side of the inner liner 21 has two bosses, which are respectively located at the upper part and the middle part of the inner liner 21. In this way, the fiber composite material shell 22 and the inner liner 21 are connected in a concave-convex manner, which can increase the bonding strength. In other cases, the number of the strengthening connection structure 213 can be set to one or more according to the product appearance.

[0049] refer to Figure 2 and Figure 4, the handle tube 6 is connected to the watch case 2. Specifically, the watch case 2 is provided with a handle tube mounting hole 201 for mounting the handle tube 6. The handle tube 6 and the handle tube mounting hole 201 are interference fit or glued. The handle 5 is inserted into the handle tube 6. A third sealing ring 73 and a fourth sealing ring 74 are respectively installed between the inner side of the handle tube 6 and the handle 5 and between the outer side of the handle tube 6 and the handle 5. Specifically, an annular groove 52 is provided on the part where the handle 5 is sleeved on the inner side of the handle tube 6, and the third sealing ring 73 is embedded in the annular groove 52. A boss 53 is provided on the part where the handle 5 is sleeved on the outer side of the handle tube 6. An annular metal stopper 8 is also sleeved on the outer side of the handle tube 6. The fourth sealing ring 74 is stuck between the metal stopper 8 and the boss 53. The metal stopper 8 and the handle 5 are interference fit to prevent the sealing ring from detaching when the handle 5 is pulled out. A threaded hole 51 is provided in the handle 5, and the threaded hole 51 is used to connect with the time adjustment component of the movement 4.

[0050] It is understandable that, although only one handlebar mounting hole 201 is provided at the 3-hour position in this embodiment, a plurality of handlebar mounting holes 201 may be provided in other implementation cases.

[0051] The watch case 2 of this embodiment is made of PEEK as the inner liner 21 and carbon fiber composite material as the outer shell 22. The carbon fiber composite material is coated on the outside of the inner liner 21 to form the unique appearance effect of the fiber watch and the functions of anti-aging and wear resistance. The inner liner 21 is made of PEEK material because the temperature of the inner liner 21 needs to reach at least 160°C during the carbon fiber pressing process so that the carbon fiber prepreg has a better flow state and finally solidifies, and the heat resistance temperature of PEEK is above 250°C, which can better meet the requirements. In addition, the density of PEEK is only 1.3g / cm 3 About 1000 square meters, which can meet the beneficial effect of the overall light weight of the carbon fiber watch. Secondly, PEEK has a high density and can achieve the waterproof effect required by the watch. At the same time, PEEK has good forming properties. In addition, PEEK can also meet the requirements of sweat corrosion resistance and bio-friendliness.

[0052] Specifically, when making the watch case 2, the PEEK liner 21 is first prepared by injection molding, and then the liner 21 is loaded into a pressing mold of a carbon fiber composite material, and the carbon fiber prepreg is filled on the outside of the liner 21. The temperature is heated to 150-160°C, and a pressure of 20-100MPa is applied at the same time. The pressure is maintained for 1-15s, so that the carbon fiber prepreg is coated on the outside of the liner 21. After cooling, the carbon fiber composite material shell 22 is formed. In this way, a watch case blank formed by the liner 21 and the shell 22 can be obtained, and finally the annular groove 212 is machined.

[0053] The carbon fiber composite material shell 22 of this embodiment has a comprehensive density of 1.28 g / cm 3The waterproof performance reaches 50m and will not be corroded by sweat. The inner liner 21 and the carbon fiber composite material shell 22 have strong bonding strength and can withstand the cold and hot shock of -20℃ to 70℃ without loosening or cracking. The watch made of the watch case 2 has a lighter wearing experience and a beautiful appearance texture.

[0054] Embodiment 2

[0055] Different from the first embodiment, the present embodiment uses PEK as the inner liner 21 and a carbon fiber and glass fiber mixed fiber composite material as the outer shell to manufacture an ultra-light watch. The manufacturing method of the watch case 2 is the same as that of the first embodiment, except that the applied pressure is 20-50MPa and the holding time is 5s-15s, so that the glass fiber can flow in the resin to form a unique texture.

[0056] Embodiment 3

[0057] This embodiment uses PEEK as the inner liner 21 and a metal fiber composite material as the outer shell to manufacture an ultra-light watch. The manufacturing method of the watch case 2 is the same as that of the first embodiment, except that the applied pressure is 50-200MPa and the pressure holding time is 10s-15s, so that the metal fiber and the resin are fully wetted to form a good bonding strength.

[0058] Embodiment 4

[0059] This embodiment uses PPS as the inner liner 21 and ceramic fiber composite material as the outer shell to make an ultra-light watch. The manufacturing method of the solid watch case 2 is the same as that of the first embodiment, except that the applied pressure is 10-40MPa and the pressure holding time is 10s-30s.

[0060] It is understandable that, in addition to the above-mentioned implementation examples, other combinations can also be implemented within the protection scope of the present invention.

[0061] In summary, the beneficial effects of the present invention are as follows: compared with the existing fiber composite watches that use metal as the inner liner, the present invention uses a heat-resistant polymer material to make the inner liner as the inner liner, which can greatly reduce the weight brought by the original metal inner liner, and reduce the risks of parts loosening and cracking caused by the poor bonding strength of the metal inner liner and the fiber composite outer shell and the large difference in thermal expansion coefficients. In addition, the manufacture of the watch case adopts a composite process of inner liner injection molding and outer fiber molding, which can achieve high-precision and high-efficiency production; compared with the existing watch manufacturing scheme of making reinforcements through additive manufacturing and then embedding the reinforcements into synthetic materials, the outer layer of the present invention uses a fiber composite material, which has a unique texture effect on the appearance, and has better corrosion resistance, aging resistance, strength and other properties. At the same time, the inner liner is processed by injection molding on the reverse side, which can achieve mass and high-efficiency production.

[0062] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for manufacturing a watch case, characterized in that: The method comprises: The heat-resistant polymer material is made into an inner liner having a cavity that passes through from top to bottom by injection molding, and at least one reinforcing connection structure for increasing the bonding strength between the inner liner and the fiber composite material is provided on the outer side of the inner liner; The inner liner is loaded into a fiber composite material forming mold, and the fiber prepreg is filled in the cavity between the outer side of the inner liner and the mold, and the inner liner is pressed and formed at a preset temperature and a preset pressure for a preset time, and the outer liner is demolded after cooling to form a watch case blank composed of a heat-resistant polymer material inner liner and a fiber composite material outer shell; Among them, the preset temperature is 150-160°C, the preset pressure is 20-200MPa, the preset time is 1-30s, and the heat-resistant polymer material is a polymer material that can withstand temperatures of 160°C and above.

2. The method according to claim 1, characterized in that The heat-resistant polymer material is PEK or PEEK or PPS.

3. The method according to claim 1, characterized in that The fiber composite material is a fiber epoxy resin composite material, and the fibers in the fiber composite material include one or more of carbon fiber, glass fiber, metal fiber, and ceramic fiber.

4. A fiber composite material watch case, characterized in that: The watch case is made based on the method described in any one of claims 1 to 3, and includes an inner liner injection-molded from a heat-resistant polymer material and a fiber composite material outer shell formed by attaching fiber prepreg to the outer side of the inner liner by molding.

5. A fiber composite material watch, characterized in that: The invention comprises a bottom cover, a watch case, a movement and a dial assembly, wherein the watch case is provided with a cavity which passes through from top to bottom, the dial assembly and the bottom cover are respectively assembled with the upper part and the lower part of the watch case and seal the cavity, the movement is arranged in the cavity, the watch case is made based on the method described in any one of claims 1 to 3, the watch case comprises an inner liner which is injection molded from a heat-resistant polymer material and a fiber composite material outer shell which is formed by attaching fiber prepreg to the outer side of the inner liner by molding, and the outer side of the inner liner is provided with at least one reinforcing connection structure for increasing the bonding strength between the inner liner and the fiber composite material.

6. The watch according to claim 5, characterized in that: The strengthening connection structure is a groove and / or a protrusion structure; The dial assembly includes an inner shadow ring, a dial, and a watch glass. The bottom cover is connected to the lower part of the watch case, and a first sealing ring is provided at the joint between the bottom cover and the watch case. The watch glass is pressed onto the upper part of the watch case through a second sealing ring. The inner shadow ring, the dial, and the movement are arranged in the cavity. The inner side of the inner tank is provided with a first boss for carrying the dial and a second boss for carrying the movement. The movement is located below the dial. The inner shadow ring is installed on the dial and below the watch glass. The inner side of the inner tank has an annular sealing groove for accommodating the first sealing ring at a position close to the bottom, and the inner side of the inner tank is processed to form an annular groove for providing a deformation space for the second sealing ring at a position close to the upper part.

7. The watch according to claim 5, characterized in that: The watch case is provided with a handlebar mounting hole for mounting the handlebar, the handlebar is interference-fitted or glued to the handlebar mounting hole, a handle is inserted into the handlebar, a third sealing ring and a fourth sealing ring are respectively installed between the inner side of the handlebar and the handlebar, and between the outer side of the handlebar and the handlebar. An annular groove for accommodating the third sealing ring is provided on the portion of the handle that is sleeved on the inner side of the handle tube; a boss is provided on the portion of the handle that is sleeved on the outer side of the handle tube, and an annular metal limiting plate is also sleeved on the outer side of the handle tube, and the fourth sealing ring is clamped between the metal limiting plate and the boss, and the metal limiting plate and the handle have an interference fit to prevent the sealing ring from detaching when the handle is pulled out.

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