A lawn rolling ball and a preparation process thereof

Abstract

The application relates to the technical field of sports product manufacturing, and discloses a lawn roll ball and a preparation process thereof, which comprises the following steps: blank pressing, cavity solidification forming, edge grinding treatment, polishing treatment, mark application and finished product inspection, so that the lawn roll ball is obtained. Through optimization of a production process flow and process innovation, the quality deviation of the continuously produced lawn roll ball is reduced, the mechanical processing deviation is avoided, the partial water absorption and shrinkage deviation of the ball body are reduced, the problem of the gravity center deviation of the lawn roll ball caused by the problem is effectively prevented, a solid foundation is laid for improving and ensuring the quality and stability of the lawn roll ball movement, the complex turning process step in the traditional process is completely replaced, the processing deviation caused by multiple clamping, tool wear, machine precision and the like is fundamentally avoided, the height consistency of each ball body shape is ensured, the mechanical processing deviation is eliminated, the production technical threshold is reduced, and convenience is provided for the popularization and application of the sports project.

Description

Technical Field

[0001] This invention relates to the field of sports equipment manufacturing technology, specifically to a lawn bowling ball and its preparation process. Background Technology

[0002] Lawn bowls is a competitive and recreational sport originating in the British court and boasting a history spanning centuries. A lawn bowl uses an asymmetrical, eccentrically shaped sphere. The surface consists of a rolling surface and two marked sides. Four balls of the same size, color, or pattern form a set. The game relies primarily on the eccentric structure to achieve the curved rolling motion. During the game, players take turns rolling their balls towards a pre-defined target ball. After all balls have been rolled, the nearest target ball is determined by visual inspection or measurement, and the score is calculated. Therefore, lawn bowls demand extremely high standards of uniform ball density, consistent shrinkage, precise eccentric contour, stable center of gravity, and repeatable trajectory.

[0003] In existing technologies, the production process of lawn bowling, such as the Australian process, involves "amino granules, preheating, curing in a universal mold, semi-finished ball blank, complex machining, grinding, polishing, marking, and inspection." This process has many inherent defects. The semi-finished ball blank made with a universal mold has uneven internal density. Due to differences in heat and pressure, the surface and core of the thermosetting plastic have significantly different shrinkage rates. To obtain the final eccentric ball, more than two complex machining processes are required. This introduces machining deviations such as machine tool positioning and fixture wear. An eccentric arc deviation exceeding 0.2mm will significantly change the trajectory. Furthermore, the secondary machining process is cumbersome, requires high operational skills, has low production efficiency, and high manufacturing costs, seriously hindering the popularization and promotion of the sport. Moreover, the uneven density within the semi-finished product leads to different water absorption and shrinkage rates in different parts. During use, the ball's center of gravity is easily shifted due to environmental temperature and humidity, seriously affecting the quality stability of the equipment and the fairness of the game.

[0004] In view of the shortcomings of the existing technology, there is an urgent need to develop a method for producing grass balls that can be formed in one cavity, has a stable center of gravity, and is produced at high efficiency and low cost. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a grass ball and its manufacturing process, which solves the problems of large machining deviations, uneven material shrinkage leading to unstable center of gravity, low production efficiency, and high costs in existing grass ball manufacturing processes.

[0006] (II) Technical Solution To achieve the above objectives, this invention discloses a process for preparing lawn bowls, comprising the following steps: Step 1: Pressing blanks: Weigh the amino granules quantitatively, and press them using a cold pressing blank mold to obtain spherical blanks of different specifications and sizes. Step 2, Cavity Curing and Shaping: The spherical blank is placed into a special mold for one-time molding in the cavity, and the cavity method is used for one-time thermosetting to obtain a shaped sphere; Step 3, edge grinding: Grind the edges of the shaped ball to remove the thin burrs on the parting line and control the dimensional and weight accuracy; Step 4: Polishing: Polish the surface of the sphere after edge grinding to make the surface color uniform and have a glossy texture. Step 5: Apply markings: Use multi-color paint to print specifications and production markings on the surface of the sphere; Step Six: Finished Product Inspection: Rolling trajectory detection is performed on standard special plastic lawn tracks, and qualified finished products are selected for warehousing.

[0007] Preferably, the amino granules in step one, by mass percentage, comprise the following components: urea-formaldehyde resin ≥67%, reinforcing wood fiber 26%, lubricant and release agent total 0.5%, adhesive 1.0%, volatile matter ≤4.5%, and pigment 0.5%.

[0008] Preferably, the preparation method of the amino granules includes the following steps: urea-formaldehyde resin, reinforcing wood fiber, lubricant, release agent, adhesive, and pigment are put into a kneader and mixed thoroughly, heated and vacuum dehydrated, and the volatile matter is controlled to be ≤4.5% to obtain a dried material. The dried material is crushed, standard particles are screened out, and the particles are fully mixed to obtain amino granules.

[0009] Preferably, the release agent comprises one or more of zinc stearate, stearic acid, microcrystalline wax, lignite wax, and ethylene bis-stearamide; the overall density of the grass ball is 1.563~1.575 g / cm³. 3 After molding, the continuous single-piece mass deviation is ≤±5g. The sphere has an asymmetrical structure with two eccentric semicircles. It is suitable for a series of specifications with diameters of 116~131mm and single sphere weights of 1.2~1.59kg.

[0010] Preferably, the different ball sizes in step one include any one of #2, #3, and #4 balls. The material usage for different ball sizes is as follows: #2 ball 1435~1450g, #3 ball 1490~1505g, and #4 ball 1555~1570g. The pressing process parameters for the cold-pressed blank are: pressure 20MPa and pre-press holding time 20~30s.

[0011] Preferably, the thermosetting molding process in step two is a tunnel press continuous pressing process, wherein the curing pressure is 25 MPa, the mold temperature is controlled in stages at 140~150℃, the preheating time is 60s, and the curing time is 120~150min.

[0012] Preferably, the edge grinding process in step three uses a belt grinding machine. Two small bearings with adjustable distance are set near the belt. The distance between the two bearings is such that when the grass ball is close to the bearing, the surface of the grass ball is in contact with the belt. During edge grinding, the grass ball is pressed tightly between the two bearings so that the edge of the ball contacts the rotating belt. When the grass ball and the belt reach a stable distance, the edge grinding of the grass ball is completed.

[0013] Preferably, after the edge grinding process, the thickness of the flash on the parting surface is 0.1~0.3mm, and the change in the mass of the sphere before and after edge grinding is <8g.

[0014] Preferably, the polishing process in step four includes the following steps: S1. Apply an appropriate amount of polishing wax to the rotating cloth wheel; S2. Hold the ball to be polished and bring it into contact with the polishing cloth wheel. The wax on the cloth wheel will make the surface of the ball shiny due to friction. S3. During the polishing process, the polishing parts of the sphere are continuously changed and adjusted to ensure that every part of the sphere is polished evenly, thereby achieving a uniform gloss effect.

[0015] Preferably, the rolling trajectory detection process in step six includes the following steps: In a space 25m long and approximately 150m² in area... 2On a horizontally laid lawn specifically designed for bowling, place the bowling balls on a standard inclined track and allow them to roll freely. Mark the position where the bowling balls stop rolling. Check if the deviation distance of the stopping point of bowling balls with the same serial number meets the standard allowable requirements. The method for judging the compliance of the stopping point distance deviation is as follows: With the track fixed, select a fixed point according to the stopping point of the bowling balls of the same specification and number. Using a circular target ball as a marker, draw a cross on the target point. Place the target ball at the intersection. Alternatively, set a circular target ball at the stopping point of the first bowling ball of the same specification and model. After setting the target ball, move the first bowling ball out of the test point and proceed... The second lawn bowls test is conducted. After the second lawn bowls stops moving, the distance between the lawn bowls and the target ball is measured. The smaller the distance between the lawn bowls and the target ball, the better. When the lawn bowls are about to collide with the target ball, the target ball can be moved aside to facilitate observation of the stopping point of the second lawn bowls. Before conducting the third lawn bowls test, the second ball should be moved out of the test point, and so on. The standard distance between the stopping point of the lawn bowls and the target ball is ≤15cm. When the stopping point of the lawn bowls occupies the position of the target ball, the stopping point distance of the lawn bowls is judged to be qualified. If the stopping point of the lawn bowls is >15cm after the lawn bowls have passed the position of the target ball, the stopping point distance of the lawn bowls is judged to be unqualified.

[0016] A type of lawn bowling ball is prepared using the aforementioned lawn bowling ball preparation process.

[0017] (iii) Beneficial technical effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The one-time molding process of grass ball using the cavity method in this invention consists of three parts: amino granules, grass ball shaping cavity mold, and grass ball curing molding process. The one-time molding of grass ball using the cavity method reduces the quality deviation of grass ball produced continuously by optimizing the production process and innovating the process, avoiding machining deviations, reducing the deviations in local water absorption and shrinkage of the ball, and effectively preventing the problem of grass ball center of gravity shift caused by these deviations. This lays a solid foundation for improving and ensuring the continuous stability of grass ball movement quality. The one-time molding using the shaping cavity mold designed according to the eccentric arc parameters completely replaces the complex machining steps in the traditional process, fundamentally avoiding the machining deviations introduced by multiple clamping, tool wear, machine tool precision, etc., ensuring the high consistency of the shape of each ball, and eliminating machining deviations.

[0018] (2) In this invention, by developing special density amino granules and combining them with cavity molding, the spheres are uniformly pressed and synchronously cured in the mold. The density distribution inside the material is uniform, eliminating the difference in shrinkage rate between the surface and the core. This effectively prevents the problem of center of gravity shift caused by different water absorption and shrinkage rates due to local density differences, and ensures the long-term performance stability of the equipment.

[0019] (3) This invention combines high-precision molds, specialized materials, and optimized curing parameters to control the quality deviation of continuously produced products within a very small range (±5g), and the trajectory and landing point deviation of the finished ball meet strict standards, ensuring product quality consistency and the fairness of the competition. Furthermore, the provided lawn bowling process is short, eliminating the most time-consuming and difficult mechanical processing steps, significantly reducing equipment investment and labor costs. Production efficiency can reach more than four times that of traditional Australian processes, creating favorable conditions for the popularization and promotion of lawn bowling. At the same time, it lowers the technical threshold for production, providing convenience for the promotion and application of the sport. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Example 1 The preparation method of #2 lawn bowling ball includes the following steps: (1) Preparation of No. 2 blank ball: Take a density of 1.57 g / cm³ 3 The grass rolling ball amino granules weigh 1435~1450g are cold-pressed into blank balls using a grass rolling ball blank cold pressing mold. The pressing process parameters for the cold-pressed blanks are: pressure 20Mpa, pre-pressing holding time 20~30s. (2) Place the No. 2 blank ball into the No. 2 grass ball shaping cavity mold, and then put the No. 2 shaping cavity mold containing the No. 2 blank ball into the tunnel-type grass ball curing molding press. According to the grass ball thermosetting molding process, the curing molding is carried out. After curing is completed, the part taken out is the grass ball semi-finished product. (3) Use a belt sander to remove the burrs from the No. 2 semi-finished grass ball to make the parting surface of the semi-finished grass ball flat and uniform. (4) Use a polishing machine to wax and polish the semi-finished ball after the flash has been removed, so that the surface of the ball has a uniform and soft luster; (5) Use a laser machine to engrave markings on the side of the polished grass ball according to the requirements of the production plan, and fill them with the corresponding color paint; (6) The grass ball with the markings made is placed on a special inclined track for motion trajectory inspection. The ball is rolled freely. The distance between the ball and the target ball after the ball stops rolling is inspected. If the distance meets the standard requirements, the ball is qualified and 2# grass ball is obtained.

[0022] The process parameters required for the preparation step in this embodiment are as follows: Tunnel-type press grass rolling ball cavity method one-time thermosetting molding process: Example 2 The preparation method of #3 lawn bowling ball includes the following steps: (1) Preparation of No. 3 blank ball: Take a density of 1.57 g / cm³ 3 The grass rolling ball amino granules weigh 1490~1505g. They are cold-pressed into blank balls using a grass rolling ball blank cold pressing mold. The pressing process parameters for the cold-pressed blanks are: pressure 20Mpa, pre-pressing holding time 60s. (2) Place the No. 3 blank ball into the No. 3 grass ball shaping cavity mold, and then put the No. 3 shaping cavity mold containing the No. 3 blank ball into the tunnel-type grass ball curing molding press. According to the grass ball thermosetting molding process, the curing molding is carried out. After curing is completed, the part taken out is the grass ball semi-finished product. (3) Use a belt sander to remove the burrs from the No. 3 semi-finished grass ball to make the parting surface of the semi-finished grass ball flat and uniform. (4) Use a polishing machine to wax and polish the semi-finished ball after the flash has been removed, so that the surface of the ball has a uniform and soft luster; (5) Use a laser machine to engrave markings on the side of the polished grass ball according to the requirements of the production plan, and fill them with the corresponding color paint; (6) The grass ball with the markings made is placed on a special inclined track for motion trajectory inspection. The ball is allowed to roll freely. The distance between the ball and the target ball after the ball stops rolling is inspected. If the distance meets the standard requirements, the ball's stopping distance is qualified.

[0023] The process parameters required for the preparation step in this embodiment are as follows: Tunnel-type press grass rolling ball cavity method one-time thermosetting molding process: Example 3 Preparation of #4 lawn bowling ball (1) Preparation of No. 4 blank ball: Take a density of 1.57 g / cm³ 3 The grass rolling ball amino granules weigh 1555~1570g. They are cold-pressed into blank balls using a grass rolling ball blank cold pressing mold. The pressing process parameters for the cold-pressed blanks are: pressure 20Mpa, pre-pressing holding time 60s. (2) Place the No. 4 blank ball into the No. 4 grass ball shaping cavity mold, and then put the No. 4 shaping cavity mold containing the No. 4 blank ball into the tunnel-type grass ball curing molding press. According to the grass ball thermosetting molding process, the curing molding is carried out. After curing is completed, the part taken out is the grass ball semi-finished product. (3) Use a belt sander to remove the burrs from the No. 4 semi-finished grass ball to make the parting surface of the semi-finished grass ball flat and uniform. (4) Use a polishing machine to wax and polish the semi-finished ball after the flash has been removed, so that the surface of the ball has a uniform and soft luster; (5) Use a laser machine to engrave the markings on the side of the polished grass ball according to the requirements of the production plan, and fill them with the corresponding color paint.

[0024] (6) The grass ball with the markings made is placed on a special inclined track for motion trajectory inspection. The ball is allowed to roll freely. The distance between the ball and the target ball after the ball stops rolling is inspected. If the distance meets the standard requirements, the ball's stopping distance is qualified.

[0025] The process parameters required for the preparation step in this embodiment are as follows: Tunnel-type press grass rolling ball cavity method one-time thermosetting molding process: Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A manufacturing process for lawn bowling balls, characterized in that: Includes the following steps: Step 1: Pressing blanks: Weigh the amino granules quantitatively, and press them using a cold pressing blank mold to obtain spherical blanks of different specifications and sizes. Step 2, Cavity Curing and Shaping: The spherical blank is placed into a special mold for one-time molding, and the spherical blank is thermo-cured and shaped in one step by cavity method to obtain a shaped sphere; Step 3, edge grinding: Grind the edges of the shaped ball to remove the thin burrs on the parting line and control the dimensional and weight accuracy; Step 4: Polishing: Polish the surface of the sphere after edge grinding to make the surface color uniform and have a glossy texture. Step 5: Apply markings: Use multi-color paint to print specifications and production markings on the surface of the sphere; Step Six: Finished Product Inspection: Rolling trajectory detection is performed on standard special plastic lawn tracks, and qualified finished products are selected for warehousing.

2. The preparation process of a lawn bowling ball according to claim 1, characterized in that: The amino granules in step one, by mass percentage, comprise the following components: urea-formaldehyde resin ≥67%, reinforcing wood fiber 26%, lubricant and release agent total 0.5%, adhesive 1.0%, volatile matter ≤4.5%, and pigment 0.5%.

3. The preparation process of a lawn bowling ball according to claim 2, characterized in that: The release agent includes one or more of zinc stearate, stearic acid, microcrystalline wax, lignite wax, and ethylene bis-stearamide; the overall density of the grass ball is 1.563~1.575 g / cm³. 3 After molding, the continuous single-piece mass deviation is ≤±5g. The sphere has an asymmetrical structure with two eccentric semicircles. It is suitable for a series of specifications with diameters of 116~131mm and single sphere weights of 1.2~1.59kg.

4. The preparation process of a lawn bowling ball according to claim 1, characterized in that: In step one, the different ball sizes include any one of #2, #3, and #4 balls. The material usage for different ball sizes is as follows: #2 ball 1435~1450g, #3 ball 1490~1505g, and #4 ball 1555~1570g. The pressing process parameters for the cold-pressed blank are: pressure 20MPa and pre-press holding time 20~30s.

5. The preparation process of a lawn bowling ball according to claim 1, characterized in that: The thermosetting molding process in step two is a continuous pressing process using a tunnel press, wherein the curing pressure is 25 MPa, the mold temperature is controlled in stages at 140~150℃, the preheating time is 60s, and the curing time is 120~150min.

6. The manufacturing process of a lawn bowling ball according to claim 1, characterized in that: In step three, the edge grinding process uses a belt grinding machine. Two small bearings with adjustable distance are set near the belt. The distance between the two bearings is such that when the grass ball is close to the bearing, the surface of the grass ball is in contact with the belt. During edge grinding, the grass ball is pressed tightly between the two bearings so that the edge of the ball contacts the rotating belt. When the grass ball and the belt reach a stable distance, the edge grinding of the grass ball is completed.

7. The preparation process of a lawn bowling ball according to claim 6, characterized in that: After the edge grinding process, the thickness of the flash on the parting surface is 0.1~0.3mm, and the change in the mass of the sphere before and after edge grinding is <8g.

8. The manufacturing process of a lawn bowling ball according to claim 1, characterized in that: The polishing process in step four includes the following steps: S1. Apply an appropriate amount of polishing wax to the rotating cloth wheel; S2. Hold the ball to be polished and bring it into contact with the polishing cloth wheel. The wax on the cloth wheel will make the surface of the ball shiny due to friction. S3. During the polishing process, the polishing parts of the sphere are continuously changed and adjusted to ensure that every part of the sphere is polished evenly, thereby achieving a uniform gloss effect.

9. The manufacturing process of a lawn bowling ball according to claim 1, characterized in that: The rolling trajectory detection process in step six includes the following steps: In a space 25m long and approximately 150m² in area... 2 On a horizontally laid lawn specifically designed for bowling, place the bowling balls on a standard inclined track and allow them to roll freely. Mark the position where the bowling balls stop rolling. Check if the deviation distance of the stopping point of bowling balls with the same serial number meets the standard allowable requirements. The method for judging the compliance of the stopping point distance deviation is as follows: With the track fixed, select a fixed point according to the stopping point of the bowling balls of the same specification and number. Using a circular target ball as a marker, draw a cross on the target point. Place the target ball at the intersection. Alternatively, set a circular target ball at the stopping point of the first bowling ball of the same specification and model. After setting the target ball, move the first bowling ball out of the test point and proceed... The second lawn bowls test is conducted. After the second lawn bowls stops moving, the distance between the lawn bowls and the target ball is measured. The smaller the distance between the lawn bowls and the target ball, the better. When the lawn bowls are about to collide with the target ball, the target ball can be moved aside to facilitate observation of the stopping point of the second lawn bowls. Before conducting the third lawn bowls test, the second ball should be moved out of the test point, and so on. The standard distance between the stopping point of the lawn bowls and the target ball is ≤15cm. When the stopping point of the lawn bowls occupies the position of the target ball, the stopping point distance of the lawn bowls is judged to be qualified. If the stopping point of the lawn bowls is >15cm after the lawn bowls have passed the position of the target ball, the stopping point distance of the lawn bowls is judged to be unqualified.

10. A type of lawn bowling, characterized in that: The grass ball is prepared using the preparation process described in any one of claims 1-9.

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