Manufacturing method and structure of leather racket frame

Abstract

The invention provides a manufacturing method and a structure of a pickup racket frame. The manufacturing method comprises the following steps: (a) impregnating a composite material with resin; (b) taking a racket-shaped core mold, and arranging an elastic body on at least one preset part outside the core mold to form an elastic body layer; winding and coating the elastomer layer with the composite material to form a composite material layer, and mutually winding to form a semi-finished product; (c) the semi-finished product is placed in a mold, the mold is heated to a preset temperature, the core mold is heated to expand, and internal pressure is formed in the semi-finished product; (d) stopping heating, and cooling the semi-finished product to be in a solidified state; (e) taking out a finished product of the leather racket from the mold; according to the manufacturing method, the integrated racket frame jointly formed by the core mold, the elastomer layer and the composite material layer is sequentially formed from inside to outside, the racket is light in weight and can maintain considerable strength and rigidity, the racket face of the racket has hitting elasticity, and meanwhile the damping effect is achieved.

Description

Technical Field

[0001] The present invention relates to a manufacturing method and structure of a racket frame, which is applied to a pickleball racket to achieve light weight, good controllability, and shock absorption effect. Background Art

[0002] Pickleball is a newly emerging ball sport in recent years, which is a mixed sport similar to tennis, badminton, and table tennis. Its playing method is closer to tennis. The pickleball court is the same as that of badminton, except that the net separating the middle is lower. The rules and playing methods of pickleball are similar to those of tennis.

[0003] The appearance of a pickleball racket is closer to that of a table tennis racket. It belongs to a racket structure without a woven net and is mainly composed of a striking part and a handle part. The striking part is flat, and both sides of the racket face are parts available for striking. These striking parts and handle parts are mostly integrally formed, but there are also applications of split technologies, such as a pickleball racket with a shock-absorbing grip disclosed in Chinese Patent CN213049277U.

[0004] In terms of material application of market pickleball rackets, most of them use carbon fiber material for the racket outer frame and plastic material inside the racket. According to various different requirements, such as frame strength, shock absorption, racket face resilience, racket face support, etc., there are further different technical applications and changes in the racket structure, material, and process.

[0005] For example, for the racket face part of a pickleball racket, if the shock absorption effect is better, the impact force of the pickleball will be absorbed by the racket face, the rebound force when hitting out will be smaller, the rebound sensitivity will be lower, the strength and hardness of the racket face will also be lower, and the feel when swinging the racket will be heavy and the control controllability will be low; on the contrary, when the shock absorption effect of the pickleball racket face is worse, the impact force of the pickleball is less absorbed by the racket face, the rebound force when hitting out is larger, the rebound sensitivity is relatively high, the strength and hardness of the racket face are also higher, the feel when swinging the racket is lighter, and the control controllability is high. Therefore, the racket structure and material affect many physical factors, and various pickleball rackets with different structures and materials are created, each with different characteristics and suitable for different users according to their preferences and physical conditions.

[0006] A shock-absorbing Pickleball racket disclosed in Chinese Patent CN114569990A, the structure of which includes a first shock-absorbing layer, a first reinforcing layer, a base layer, a second reinforcing layer and a second shock-absorbing layer arranged in sequence. The first shock-absorbing layer and the second shock-absorbing layer are made of buffer rubber. Among them, the buffer rubber is made by the following steps: putting natural rubber and reinforcing fibers into a mixer, kneading at 140°C for 7 minutes to obtain masterbatch rubber. At room temperature, mixing the masterbatch rubber, stearic acid, accelerator, antioxidant and sulfur, then vulcanizing at 143°C for 15-20 minutes, and then controlling the discharge temperature at 110-130°C, rolling, slicing at a thickness of 3 mm, and cooling to obtain the buffer rubber.

[0007] Another existing Pickleball racket frame structure, such as a Pickleball racket disclosed in Chinese Patent CN115155026A, is characterized in that: it includes a racket body and a handle, the handle is connected to one side of the racket body, and the racket body sequentially includes an upper panel, a lower panel and a composite inner panel sandwiched between the upper panel and the lower panel from top to bottom. The composite inner panel is sequentially composed of an upper honeycomb panel, a shock-absorbing layer and a lower honeycomb panel from top to bottom, and the upper honeycomb panel and the lower honeycomb panel are both provided with honeycomb structures; the upper panel and the lower panel are set as an integrally formed structure and evenly wrap the outside of the composite inner panel, and a edging strip is evenly arranged between the side edge of the composite inner panel and the upper panel and the lower panel.

[0008] There is also an existing Pickleball racket frame structure, such as a multi-layer composite Pickleball racket disclosed in Chinese Patent CN112870660A, which is characterized in that: it includes a racket board and a racket handle, the racket handle is connected to the racket board, and a composite inner core layer is arranged inside the racket board. The composite inner core layer at least includes a first inner core layer and a second inner core layer, the first inner core layer is bonded to the second inner core layer, and the first inner core layer and the second inner core layer are both provided with honeycomb structures.

[0009] The aforementioned patents are all prior arts related to Pickleball rackets. The first patent is about the technology of Pickleball rackets, and the second and third patents are about the structural technology of Pickleball rackets. Further analysis shows that the first and second patents are mainly technologies developed for strengthening shock absorption or vibration absorption functions, with a structure of shock-absorbing layers made of rubber materials stacked on the racket surface in multiple layers; inside the racket surfaces of the second and third patents, they are both in a honeycomb structure, which not only maintains the rigidity of the racket surface, but also the honeycomb structure has good durability and environmental resistance.

[0010] The above three patented technologies all focus on a multi-layer inner core structure to cushion the impact of the pique ball and achieve a better shock absorption effect. However, because the impact of the pique ball is consumed more, the player needs to use more force to make the pique ball fly the same distance. When the pique ball contacts the racket face, the racket face is deeply concave, resulting in large friction, making it more difficult to control the rebound direction of the ball. Moreover, the honeycomb structure is prone to produce different rebound forces due to hitting different positions on the honeycomb frame or honeycomb holes. On the other hand, a large number of buffer core layers will also increase the overall weight of the racket, causing a burden on the player's hands. Furthermore, a pique racket with enhanced shock absorption effect is not suitable for children and elderly users with less swinging power. In addition, the existing honeycomb core layer has a very high production cost and a relatively complicated process. Summary of the invention

[0011] In view of this, the manufacturing method of the pike racket frame disclosed in the present invention comprises the following steps: (a) impregnation with resin: impregnating a composite material with resin; (b) covering a core mold: taking a core mold in the shape of a racket, which is made of polymethacrylimide, and providing an elastomer at at least one preset position outside the core mold to form an elastomer layer; then winding the composite material around the elastomer layer to form a composite material layer, and the composite material layers are wound together to form a semi-finished product; (c) heating and pressurizing: placing the semi-finished product in a mold, and heating the mold to a preset temperature, and the core mold expands due to the heat after heating. Internal pressure is formed inside the semi-finished product; (d) cooling and solidification: heating is stopped to cool the semi-finished product to a solidified state; (e) finished product is formed; a finished racket frame is taken out from the mold; the manufactured pique racket frame is an integrated racket frame formed by a core mold, an elastomer layer and a composite material layer in sequence from the inside to the outside. In addition to utilizing the elastomer layer to achieve a shock-absorbing effect, the interior of the striking part is made of polymethyl methacrylate, which has relatively high strength and rigidity, and the racket face has better return elasticity. The overall racket is light in weight, and the handling feel is improved, which can also reduce the manufacturing cost.

[0012] The main purpose of the present invention is to provide a method for manufacturing a pike racket frame and its structure, wherein the core mold is made of polymethacrylimide (PMI) material, which expands when heated during the heating step and generates internal pressure to allow the semi-finished product to completely fill the mold cavity space without any pressurizing device, thereby effectively reducing the manufacturing cost.

[0013] Another object of the present invention is to provide a method for manufacturing a pike racket frame and its structure, wherein the core mold screen eliminates the honeycomb structure, so there is no need to carry out a processing flow for forming the core mold honeycomb structure, which effectively simplifies the process and saves manufacturing costs.

[0014] Another object of the present invention is to provide a manufacturing method and structure of a pick racket frame, in which the core mold is made of polymethacrylimide (PMI) material to replace the elastic layer of the existing honeycomb structure, so as to improve the support of the striking part, have higher hardness and rigidity, the racket face has better return elasticity, enhance the control feel of the hitting direction, but still has a shock absorption effect.

[0015] Another object of the present invention is to provide a manufacturing method and structure of a pick racket frame, with a core mold made of polymethacrylimide (PMI) material as the base body. Compared with the existing multi-layer elastic layer structure, the overall weight of the racket is lighter, effectively reducing the burden when swinging the racket, and is suitable for children or the elderly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a manufacturing flow chart of a preferred embodiment of the present invention.

[0017] Figure 2 It is a schematic diagram of covering the core mold in step (b) of a preferred embodiment of the present invention.

[0018] Figure 3 It is a schematic diagram of the mold and heating device of a preferred embodiment of the present invention.

[0019] Figure 4 It is a three-dimensional external view schematic diagram of the racket frame of a preferred embodiment of the present invention.

[0020] Figure 5 It is a schematic diagram of a plane cross-section of the racket frame of a preferred embodiment of the present invention.

[0021] Figure 6 It is a schematic diagram of a plane cross-section of the striking part of a preferred embodiment of the present invention.

[0022] Figure 7 It is a schematic diagram of a plane cross-section of the racket frame of the second embodiment of the present invention.

[0023] Figure 8 It is a schematic diagram of a plane cross-section of the racket frame of the third embodiment of the present invention.

[0024] Figure 9 It is a schematic diagram of a plane cross-section of the racket frame of the fourth embodiment of the present invention.

[0025] Figure 10 It is a schematic diagram of a plane cross-section of the racket frame of the fifth embodiment of the present invention.

[0026] DESCRIPTION OF REFERENCE NUMERALS 10: Core mold 11: Striking part 12: Handle part 20: Elastomer 20’: Elastomer layer 30: Composite material 30': Composite material layer 40: Mold 41: Mold cavity 42: Heating device 43: Heating device 50: Semi-finished product 60: Finished racket frame. Detailed implementation method

[0027] First, please refer to Figure 1 to FIG. 4. A manufacturing method of a Pickleball racket frame provided by the present invention includes the following steps: (a) Impregnating resin: Impregnating a composite material 30 with resin.

[0028] (b) Coating the core mold: Taking a core mold 10 in the shape of a racket, made of poly(methacrylimide) (PMI), the core mold 10 is solid and has a striking part 11 and a handle part 12; an elastomer 20 is provided at at least one preset position outside the core mold 10, mainly on both striking surfaces of the striking part 11, to form an elastomer layer 20'; then winding and coating the composite material 30 outside these core mold 10 and the elastomer layer 20' to form a composite material layer 30', and these mutually wound composite material layers 30', elastomer layer 20' and core mold 10 together form a semi-finished product 50.

[0029] (c) Heating and pressurizing: Placing the semi-finished product 50 into a mold 40 having a mold cavity 41, and heating the mold 40 to a preset temperature, which can be heated by using two heating devices 42, 43 provided on both sides of the mold 40; the heating temperature exceeds the melting point temperature of the composite material; the heating temperature value range is 120°C to 180°C; after heating, the core mold 10 expands due to heat and forms an internal pressure inside the semi-finished product 50.

[0030] (d) Cooling and curing: Stopping heating and cooling the semi-finished product 50 to a solidified state; (e) Finished product forming; Taking out a finished racket frame 60 from the mold.

[0031] For the finished racket frame 60 manufactured according to the aforementioned manufacturing method, please refer to FIGS. 4 to Figure 6 , and its structure includes: A core mold 10, made of poly(methacrylimide) (PMI) material, which integrally forms a striking part 11 and a handle part 12; the core mold 10 is solid.

[0032] An elastomer layer 20', made of a plastic material, is attached to the two striking surfaces of the striking part.

[0033] A composite material layer simultaneously wraps these mandrels and the elastomer layer, and forms an integrated racket frame for these striking parts and the handle part.

[0034] The Pickleball racket frame structure made by the above manufacturing method uses the mandrel 10 made of polymethacrylimide (PMI) material, combines with the elastomer layer 20' provided on the striking surface of the striking part 11, and then is completely wrapped by the composite material 30 in a winding manner. The integrated racket frame formed jointly can not only achieve the shock absorption effect by using the elastomer layer 20', but also has relatively high strength and rigidity due to the polymethacrylimide (PMI) material inside the striking part 11. The racket face has better return elasticity, the overall racket is light in weight, the handling feel is improved, and the manufacturing cost can be reduced. Therefore, it has high economic benefits and practicality.

[0035] To further understand the structural features, technical means and expected technical effects of the present invention, the usage method of the present invention will be described as follows: Please refer to Figure 1 and Figure 2 , for the manufacturing process of the present invention, first, in step (a), the resin impregnation step is to impregnate a composite material 30 with resin. The composite material 30 can be one of carbon fiber, glass fiber, graphene, etc. In step (b), the mandrel wrapping step is to paste an elastomer 20 on both striking surfaces of the polymethacrylimide (PMI)-material mandrel 10 in the shape of a racket to form an elastomer layer 20'. It can be completely pasted or partially pasted. The elastomer layer 20' can be one of thermoplastic rubber (TPR), thermoplastic polyurethane (TPU), thermoplastic elastomer (TPE), etc. Then, the composite material 30 is wound and wrapped outside these mandrels and the elastomer layer 20' to form a composite material layer 30', that is, the striking part 11 and the handle part 12 with the elastomer layer 20' pasted are both completely wound and wrapped by the composite material 30 to form a semi-finished product 50.

[0036] Please refer to FIG. 3. In step (c), heat and apply pressure. Place the semi-finished product 50 in the cavity 41 of the mold 40. After closing the mold, start heating the mold 40 using the heating devices provided on both sides of the mold 40. The heating temperature exceeds the melting point temperature of the composite material, approximately 120°C to 180°C. When heating, the core mold 10 expands due to heat and forms an internal pressure inside the semi-finished product 50, thereby causing the semi-finished product 50 to fill the entire cavity. When the heating exceeds the melting point temperature of the composite material, the composite material layer 30' softens and melts to completely cover the outside of the entire semi-finished product 50.

[0037] In step (d), cool and solidify. After stopping heating, first cool to a preset temperature to gradually solidify and form the semi-finished product 50 inside the mold. Please refer to FIG. 4. In step (e), form the finished product, that is, take out a finished badminton racket frame 60 from the mold 40.

[0038] Regarding the structure of the finished badminton racket frame (60) of the present invention, please refer to FIGS. 4 and 6. In the hitting part 11, from the inside to the outside, there are successively these core molds 10, the elastomer layer 20', and the composite material layer 30'; in the handle part 12, from the inside to the outside, there are successively these core molds 10 and the composite material layer 30'.

[0039] The badminton racket frame structure of the present invention is manufactured through five processes: (a) impregnating resin, (b) covering the core mold, (c) heating and applying pressure, (d) cooling and solidifying, and (e) forming the finished product. It forms an integrated badminton racket frame jointly formed by a core mold 10, an elastomer layer 20', and a composite material layer 30' in sequence from the inside to the outside, and can effectively achieve the following effects: First, in step (c) of heating and applying pressure, since the core mold 10 is made of polymethacrylimide (PMI) material, it gradually expands when heated and generates internal pressure, so that the semi-finished product 50 completely fills the space of the cavity 41 without setting any pressurizing devices or equipment, thus effectively reducing the manufacturing cost.

[0040] Second, the core mold 10 of the present invention is made of polymethacrylimide (PMI) material. In step (b) of covering the core mold, it is carried out in its original physical structure state without pre-processing the core mold 10 into a honeycomb structure. Compared with the existing technology using a honeycomb-shaped elastic layer, the present invention can effectively simplify the process and thus save the manufacturing cost of forming the honeycomb structure of the core mold.

[0041] Third, the core mold 10 of the present invention replaces the existing honeycomb structure elastic layer with polymethacrylimide (PMI) material. In contrast, the tissue density of the core mold 10 is more dense, and the resilience after contact with the badminton at various parts of the hitting part 11 is more consistent, solving the problem that the honeycomb structure is prone to generating different resilience when hitting different positions such as the honeycomb frame or the honeycomb nest.

[0042] Fourth, the core mold 10 of the present invention replaces the elastic layer of the existing honeycomb structure with polymethacrylimide (PMI) material. In addition to the shock-absorbing effect of the core mold 10 itself, the support of the striking part can be improved, and it has higher hardness and rigidity. The racket face has better return elasticity, which enhances the control feel of the hitting direction, and solves the problems of large friction caused by strengthening the shock-absorbing function in the prior art, and it is more difficult to control the rebound and flying direction of the ball.

[0043] 5. The core mold 10 made of polymethacrylimide (PMI) is used as the base, and the structural design occupies a larger volume of the overall racket frame. Compared with the existing multi-layer elastic layer structure, the overall racket is lighter, which effectively reduces the burden when swinging the racket and is suitable for children or the elderly.

[0044] Please refer to Figure 7 , which is the second embodiment of the present invention, wherein the core mold 10 is preliminarily formed into a solid striking portion 11 and a hollow grip portion 12 in an integrated manner before processing, and then the pike racket frame process of the present invention is started. The racket frame product 60 manufactured has the grip portion 12 in a closed hollow state.

[0045] Please refer to Figure 8 , which is the third embodiment of the present invention, wherein the core mold 10 is preliminarily formed into a hollow striking portion 11 and a solid grip portion 12 in an integrated manner before processing, and then the pike racket frame process of the present invention is started. The manufactured racket frame product 60 has the striking portion 11 in a closed hollow state.

[0046] Please refer to Figure 9 , which is the fourth embodiment of the present invention, wherein the core mold 10 is preliminarily formed with the hollow striking portion 11 and the hollow grip portion 12 in an integrated manner before processing, and then the pike racket frame process of the present invention is started. The manufactured racket frame product 60 has the striking portion 11 and the grip portion 12 in a closed hollow state. A preset number of spaces can also be formed in the core mold 10 as required.

[0047] The second, third and fourth embodiments mentioned above mainly utilize the internal structure of the core mold 10 to make changes. The hollow structure can make the weight of the entire racket lighter, and the hollow volume can be adjusted according to needs, thereby producing pique rackets of different weights, and having the technical effect of adjusting the racket weight. Other manufacturing methods, structures, assembly methods, technical applications, actions and usage states, and the expected technical effects are all exactly the same as those of the first embodiment mentioned above.

[0048] Please refer to Figure 10, which is the fifth embodiment of the present invention. The thickness of the core mold 10 is the thickest at the striking part 11 on the other side of the grip part 12 and gradually thins towards the grip part 12. In other words, the thickness at the uppermost end of the striking part 11 is D1, and the thickness at the lowermost end of the striking part 11 is D2, that is, the thickness at the connection part with the grip part 12 is D2. The thickness D1 at the upper end is greater than the thickness D2 at the lower end. The thickness of the striking part 11 tapers from the upper end (D1) towards the lower end (D2), making the hitting surface of the striking part 11 a slightly inclined plane.

[0049] This embodiment mainly provides a pick racket frame with another appearance state. This design of the tapering hitting surface can make the overall racket lighter, and the center of gravity position of the overall racket will be at different positions due to different degrees of tapering to meet the requirements of different racket center of gravity positions. Therefore, it has the technical effect of adjusting the center of gravity position of the racket. Other processes, structures, assembly methods, technical applications, operations, usage states, and expected technical effects of this embodiment are exactly the same as those of the foregoing first embodiment.

[0050] In summary, the manufacturing method and structure of the pick racket frame disclosed in the present invention are a pick racket frame structure manufactured through five processes: (a) impregnating resin, (b) covering the core mold, (c) heating and pressurizing, (d) cooling and curing, and (e) forming the finished product. It is an integrated racket frame formed by sequentially forming a core mold, an elastomer layer, and a composite material layer from the inside to the outside. In addition to achieving a shock absorption effect by using the elastomer layer, the inside of the striking part is made of polymethacrylimide (PMI) material, which has relatively high strength and rigidity. The hitting surface of the racket has better return elasticity, the overall racket is light in weight, the handling feel is improved, and the manufacturing cost can be reduced, making the overall truly have industrial practicability and cost - effectiveness.

[0051] The above are the specific embodiments of the present invention and the technical principles applied. If changes are made according to the concept of the present invention and the functions and effects generated still do not exceed the spirit covered by the specification and the drawings, they should all be within the scope of the present invention.

Claims

1. A manufacturing method of a pick racket frame, characterized in that, Comprising the following steps: (a) Impregnating with resin: Impregnating a composite material with resin; (b) Coating the core mold: Taking a core mold in the shape of a racket, made of polymethacrylimide, with an elastomer provided at at least one preset part outside the core mold to form an elastomer layer; then winding and coating the composite material around the core mold and the elastomer layer to form a composite material layer, and the mutually wound composite material layers, elastomer layer and core mold together form a semi-finished product; (c) Heating and pressurizing: Placing the semi-finished product into a mold having a cavity, and heating the mold to a preset temperature. After heating, the core mold expands due to heat and forms an internal pressure inside the semi-finished product; (d) Cooling and curing: Stopping heating and cooling the semi-finished product to a cured state; (e) Finished product forming: Taking out a finished racket frame from the mold.

2. The manufacturing method of the pick racket frame according to claim 1, characterized in that, The core mold has a striking part and a handle part; the elastomer is provided on the two striking surfaces of the striking part.

3. The manufacturing method of the pick racket frame according to claim 1, characterized in that, The core mold is in a solid shape or a hollow shape.

4. The manufacturing method of the pick racket frame according to claim 1, characterized in that, The heating temperature in step (c) exceeds the melting point temperature of the composite material; the heating temperature value range is 120°C to 180°C.

5. The manufacturing method of the pick racket frame according to claim 1, characterized in that, For the heating operation in step (c), two heating devices are provided on both sides of the mold for heating.

6. The manufacturing method of the pick racket frame according to claim 1, characterized in that, The elastomer material is TPR thermoplastic rubber, TPU thermoplastic polyurethane or TPE; the composite material is carbon fiber, glass fiber or graphene.

7. The manufacturing method of the pick racket frame according to claim 1, characterized in that, For the pressurizing operation in step (c), resin injection molding technology can be further applied.

8. The structure of a pick racket frame, characterized in that, Including: A core mold, made of polymethacrylimide material, having a striking part and a handle part formed integrally; An elastomer layer, made of a plastic material, attached to the two striking surfaces of the striking part; A composite material layer, simultaneously coating the core mold and the elastomer layer, and forming an integrated racket frame of the striking part and the handle part.

9. The structure of the pick racket frame according to claim 8, characterized in that, The core mold is in a hollow shape, a solid shape or a partially hollow shape.

10. The structure of the pick racket frame according to claim 8, characterized in that, The thickness of the core mold is the thickest at the striking part on the other side of the handle part and gradually thins towards the handle part.

11. The structure of the pick racket frame according to claim 8, characterized in that, Wherein the elastomer covers the handle part.

12. The structure of the pick racket frame according to claim 8, characterized in that, The elastomer layer is TPR thermoplastic rubber, TPU thermoplastic polyurethane or TPE; the composite material is carbon fiber, glass fiber or graphene.

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