A dart body and a method of forming the same

Abstract

This invention discloses a dart body and its molding method, belonging to the field of competitive dart manufacturing. It aims to solve the shortcomings of traditional dart bodies with flexible O-rings, such as easy wear upon impact, difficulty in balancing feel and O-ring lifespan, and inability to adapt to different scenarios. The metal substrate of this dart body is divided into a smooth arc section at the dart head, a grip buffer section, and a tail section. The smooth dart head eliminates cutting wear during dart collisions. The grip section features an annular mounting groove with 0.4-1mm spacer ribs. The interference of the flexible O-ring is controlled within 0.05-0.1mm to achieve a balance between feel and wear resistance. The molding method first calibrates the basic dimensions of the substrate and O-ring, calculates the equivalent collision arc and critical groove depth based on the dart collision angle, selects the interference amount according to usage requirements to calculate the actual machining groove depth, then machines the groove and assembles the O-ring. Based on the interference amount, three types of products are categorized: long service life, products that balance service life and feel, and products with a strong feel, suitable for recreational, training, and professional competition scenarios.

Description

Technical Field

[0001] This invention belongs to the field of competitive darts manufacturing technology, specifically a dart body and its forming method. Background Technology

[0002] A dart generally consists of a needle, a shaft, a metal shaft body, and winglets. The needle is attached to the front of the shaft, and the winglets are attached to the rear of the shaft via the metal shaft body. The shaft, as the gripping part when throwing, plays a crucial role in the overall composition of a dart.

[0003] Currently, most anti-slip darts use tungsten alloy or brass as the base material, and achieve a non-slip grip through machined knurling, annular grooves, and other textured structures. However, simply adding textured structures can affect hand comfort. Therefore, some products also add flexible O-rings to the annular grooves on the dart body to optimize the grip feel.

[0004] In competitive darts, the rules stipulate that three darts are thrown per round. The later dart is highly likely to collide with the dart already fixed to the target, and it's extremely common for two darts to cross each other. When two darts collide, the curved tip of the later dart continuously scrapes against the flexible O-ring of the earlier dart. The textured tip of the dart acts like a miniature cutting edge, and repeated scraping and compression of the O-ring quickly causes it to crack, flake, and lose its elasticity. Currently, existing products in the industry only rely on thickening the flexible O-ring to slow down wear, failing to eliminate the cutting damage at the source of impact friction.

[0005] The thicker the flexible O-ring design, the more of its protruding annular groove, which, while improving the grip, significantly reduces its lifespan. Experiments have shown that when the interference (the amount of the flexible O-ring protruding from the annular groove) reaches 0.1mm, a simulated impact test with a 4800Hz fascia gun shows that the flexible O-ring shows significant damage in just 15 seconds (approximately 1200 impacts), and the wear no longer accelerates after 40 seconds.

[0006] It is evident that traditional knurled dart bodies without flexible O-rings have insufficient anti-slip properties due to shallow grooves, while deeper grooves and sharper textures can scratch fingers. At the same time, metal conducts heat quickly, making it cold to hold in low-temperature environments, which can easily cause hand soreness during long-term training. If a flexible O-ring is simply designed, it will suffer from collision wear and have a short service life. The two solutions are incompatible.

[0007] Therefore, existing products cannot accurately balance the grip feel with the lifespan of the flexible O-ring, and cannot make differentiated and standardized designs for different scenarios such as leisure, training, and professional competitions. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dart body and its forming method.

[0009] The technical problem solved by this invention is achieved through the following technical solution:

[0010] A dart body includes a metal dart body base and multiple flexible O-rings. The metal dart body base is divided into a head section, a grip buffer section, and a tail section along its axial direction. The head section has a smooth arc surface on its outer surface. The grip buffer section has several annular mounting grooves evenly distributed along its axial direction. An integrally formed spacer rib is formed between two adjacent annular mounting grooves. The width of the spacer rib is 0.4-1mm. A flexible O-ring is fitted inside the annular mounting groove. The flexible O-ring protrudes from the annular mounting groove by 0.05-0.1mm.

[0011] Moreover, the flexible O-ring has a surface with raised and recessed patterns.

[0012] Moreover, the flexible O-ring is made of rubber or soft plastic.

[0013] Furthermore, a chamfered structure is provided at the opening of the annular assembly groove.

[0014] A method for forming a dart body, characterized by comprising the following steps:

[0015] Step 1: Based on the selected metal dart body base, measure the outer diameter D1 of the front end of the dart head section, the outer diameter D2 of the metal dart body base, and the length La of the dart. At the same time, calibrate the axial radius Rn of the contact point and the base mating radius Rm=D1 / 2.

[0016] Step 2: Determine the basic dimensions of the flexible O-ring, including the inner diameter A1, axial width W1, and radial thickness B1.

[0017] Step 3: Define the assembly layout area for the flexible O-rings on the metal dart body base, and reserve the location for the annular assembly groove;

[0018] Step 4: Calculate the equivalent radius R of the collision contact arc based on the collision angle α between the two darts;

[0019] Step 5: Based on the calculated equivalent arc radius R of the collision contact, use the critical groove depth calculation formula to solve for the critical groove depth B at which the flexible O-ring just makes contact when the two darts collide.

[0020] Step 6: Select the interference amount between the annular assembly groove and the flexible O-ring assembly based on the product positioning;

[0021] Step 7: Calculate the actual machining groove depth of the metal dart body by combining the critical groove depth B with the selected interference amount;

[0022] Step 8: Design the spacer ribs between the flexible O-rings, and control the width P of the spacer ribs within the range of 0.4mm-1mm;

[0023] Step 9: Based on the inner diameter A1 of the flexible O-ring, the axial width W1, the actual machining groove depth, and the width of the spacer ribs, form an annular assembly groove on the metal dart body substrate.

[0024] Step 10: Install the flexible O-ring onto the annular assembly groove of the metal dart body, thus completing the forming process of the entire dart body.

[0025] Furthermore, the formula for calculating the equivalent radius R of the collision contact circle based on the included angle α between the two darts is as follows:

[0026]

[0027] Where Rn is the radius of the arc of the friction transition zone of the dart head section, α is the collision angle between the two darts, and Rm is the matrix mating radius.

[0028] Furthermore, the formula for calculating the critical trench depth is as follows:

[0029]

[0030] Where R is the equivalent radius of the collision contact arc, B1 is the radial thickness of the flexible O-ring, W is the width of the annular assembly groove, W=W1, and b is the depth of the groove chamfer.

[0031] Furthermore, the method for selecting the interference amount of the annular assembly groove and the flexible O-ring assembly based on product positioning is as follows:

[0032] Long service life: interference < 0, groove depth B is greater than the critical groove depth, there is an assembly gap between the flexible O-ring and the groove wall, and there is no squeezing wear upon collision;

[0033] Balancing lifespan and feel: 0.05mm≤interference≤0.1mm, balancing grip feel with the wear resistance and lifespan of flexible O-rings;

[0034] Excellent handling: interference ≥0.1mm, flexible O-ring protrudes from the dart body surface, maximizing damping and anti-slip effect.

[0035] Furthermore, the formula for calculating the actual machining groove depth is:

[0036] Actual machining groove depth = critical groove depth B - interference amount.

[0037] The advantages and positive effects of this invention are:

[0038] 1. This invention designs the dart head section as a smooth, rounded surface without any texture, completely eliminating the sharp protrusions of the cuttable flexible O-ring. The contact between darts is merely sliding friction on the smooth rounded surface, with no microscopic cutting action, thus completely eliminating the core wear-inducing factor of the flexible O-ring. Simultaneously, the smooth, rounded dart head avoids hard textures and scratches upon impact, preventing dense scratches from being left on the metal dart body surface during collision. Over long-term use, the metallic luster and integrity of the dart body are better maintained, simultaneously improving the product's appearance and durability.

[0039] 2. This invention combines the equivalent arc calculation formulas for the dart collision angle α, the dart head radius Rn, and the base radius Rm to accurately simulate the contact profile under arbitrary cross-impact conditions in real throwing. It precisely locates the critical boundary at which the flexible O-ring will make contact upon impact. All dimensions are designed to fit the forces experienced in real competitive throwing, rather than simply being derived from static dimensions, ensuring the design aligns with actual usage conditions. Based on the critical groove depth calculation formula, the ultimate groove depth benchmark for the flexible O-ring to just make contact upon dart impact is defined. Then, through a three-level standardized definition of interference, precise layered positioning of the product is achieved. The 0.4-1mm narrow range of spacer ribs is optimized, balancing structural strength and grip feel. Processing parameters are quantifiable and can be standardized for mass production. Different positioning products do not require re-deriving the entire structure; only the interference amount needs to be adjusted to achieve differentiated development, significantly reducing R&D, mold making, and processing trial-and-error costs.

[0040] 3. The present invention features a segmented arrangement of flexible O-rings. When gripped, the flexible material isolates the coldness of the metal and cushions the pressure on the hand, significantly reducing fatigue during long-term training. The surface of the rubber ring is further enhanced with circumferential arc-shaped ridges to improve anti-slip friction, eliminating the need to deepen the metal grooves and avoiding sharp metal textures from scratching the fingers.

[0041] 4. The flexible O-ring of this invention can be selected from a variety of colors such as red, blue, and black. It can be matched with alternating colors in segments and symmetrical two-color combinations. Without changing the structure of the metal base mold, multiple appearances can be achieved by simply changing the rubber ring, which enriches the product appearance. No additional mold opening is required, which controls the mass production cost while meeting the personalized appearance needs of consumers. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of the present invention;

[0043] Figure 2 for Figure 1 Sectional view along axis AA;

[0044] Figure 3 This is a schematic diagram illustrating the structure of the present invention in the state of throwing a dart;

[0045] Figure 4 This is a schematic diagram of the structure of the dart F2 of the present invention passing over the flexible O-ring of the dart F1 body;

[0046] Figure 5 This is a schematic diagram illustrating the arc structure at the impact point of the dart F2 according to the present invention;

[0047] Figure 6 This is a cross-sectional view of the metal dart body substrate of the present invention;

[0048] Figure 7 This is a schematic diagram of the structure of the flexible O-ring of the present invention;

[0049] Figure 8 This is a schematic diagram illustrating the structure of the dart impact point in this invention;

[0050] Figure 9 This is a top view illustrating the point of impact of the dart in this invention;

[0051] Figure 10 This is a schematic diagram illustrating the variation of the actual circular arc R at the impact point PO under the included angle α according to the present invention.

[0052] Figure 11 This is a schematic diagram of the structure of the dart F2 when the front arc of the dart F2 passes near the flexible O-ring of the dart F1;

[0053] Figure 12 The following is a comparison of the throwing effects of smooth and non-smooth dart head samples according to the present invention (Figure (a) is a photograph of the dart head sample with textured surface after actual throwing; Figure (b) is a photograph of the dart head sample with smooth outer surface after actual throwing).

[0054] Explanation of reference numerals in the attached figures

[0055] 1-Dart head section, 2-Grip buffer section, 3-Flexible O-ring, 4-Dart tail connection section, 5-Annular assembly groove, 6-Spacer rib, 7-Protruding ridge, 8-Metal dart body base. Detailed Implementation

[0056] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings:

[0057] like Figures 1-2 As shown, a dart body includes a metal dart body base 8 and multiple flexible O-rings 3. The metal dart body base is divided into a dart head section 1, a grip buffer section 2, and a dart tail connecting section 4 along its axial direction. Its innovation lies in the fact that the outer surface of the dart head section is free of knurling, grooves, and fine textures, and is a smooth arc surface. It is the reference area for dart impact contact. The smooth surface can eliminate the cutting friction of the flexible O-rings when darts collide, thereby reducing the wear of the flexible O-rings from the source.

[0058] Real-world testing data shows that after only 6666 throws and 5332 impacts, the textured darthead sample showed visible damage to its flexible O-ring; while the smooth-surfaced darthead sample showed almost no damage to its flexible O-ring after 44333 throws and 35466 impacts. Figure 12 As shown.

[0059] like Figure 6 , 7 As shown, several annular mounting grooves 5 are evenly distributed along the axial direction of the grip buffer section. An integrally formed spacer 6 is formed between adjacent annular mounting grooves. The width of the spacer 6 is 0.4-1mm. The smaller the width of the spacer 6, the stronger the grip damping feel. When the width of the spacer 6 is less than 0.4mm, the structural strength of the dart body is insufficient, making it prone to compression deformation. A flexible O-ring is fitted within the annular mounting groove, and the amount of the flexible O-ring protruding from the annular mounting groove (interference amount) is 0.05-0.1mm. The flexible O-ring has a surface with raised and recessed patterns. In this embodiment, it has a structure with raised ridges 7 spaced circumferentially along the outer surface of the ring body, and the cross-section of the raised ridges is arc-shaped. The flexible O-ring is made of rubber or soft plastic. The flexible O-ring can be in various colors such as red, blue, and black, with segmented color matching on the grip buffer section to achieve differentiated decoration of the dart body's appearance.

[0060] To enhance the durability of the dart body, a chamfered structure is provided at the opening of the annular assembly groove to reduce wear on the groove opening.

[0061] In dart design, given a fixed radial thickness B1 of the flexible O-ring, a fixed chamfer depth b, and a fixed groove width W or axial width W1 of the flexible O-ring, the critical condition for the groove depth B to contact the flexible O-ring on dart F1 is determined when the groove depth B meets the critical condition requirements. Based on this critical condition, the design can determine whether the flexible O-ring is completely protected or whether a certain amount of interference is allowed.

[0062] Because darts rules stipulate three darts are thrown each time, the first dart (F1) is already on the dartboard before the second and third darts are thrown. Therefore, there's a probability that the second dart (F2) will collide with the first dart (F1). The magnitude of this probability usually depends on the skill level of the thrower; for professional players, this probability is very high. And during the collision, there's a certain probability that something will happen... Figure 3 The state shown.

[0063] If the body of dart F2 then passes over the area where the flexible O-ring of dart F1 is located, the situation is as follows: Figure 4 As shown, the specific combination is as follows: Figure 5As shown, the arc (the arc at the impact point on dart F2), the width of the annular mounting groove on the body of dart F1, and the dimensional changes after the flexible O-ring mates with the annular mounting groove will all affect the specific effect.

[0064] In actual dart flight, there is usually an angle α between the darts, as shown in the reference. Figure 9 and reference to the pattern of change Figure 10 In summary, when the arc of the dart head of dart F2 passes near the flexible O-ring of dart F1, the following analysis should be performed: Figure 11 As shown. By Figure 11 It can be seen that the boundary conditions are met only when P2 (the contact point between the upper edges of the two side walls of the annular assembly groove of dart F2 and dart F1) is at the junction of the upper end of the groove side wall and the chamfer, and point P1 (the contact point between the front arc of dart F2 and the flexible O-ring) is at the uppermost end of the flexible O-ring. For R, when R increases, there is no collision contact between dart F2 and the flexible O-ring of dart F1; when R decreases, dart F2 and the flexible O-ring of dart F1 will collide. Since the collision will damage the flexible O-ring, the boundary conditions need to be analyzed. Figure 10 If the impact point is P0, D2 > D1 in general, so D1 can be taken as the boundary condition. In this case, the relationship between the dimensions is as follows: the matrix mating radius Rm = D1 / 2;

[0065] (1);

[0066] (2);

[0067] (3);

[0068] From equations (2) and (3), we can obtain (4);

[0069] (5);

[0070] From (4) and (5), we can obtain (6);

[0071] According to the Pythagorean theorem, (7);

[0072] From equations (1), (6), and (7), we can obtain (8);

[0073] From equation (8), we can obtain .

[0074] Where U is half the chord length of the intersection line of the equivalent circular arc R and the groove where the O-ring is located, B is the total groove depth of the groove where the O-ring is located, B1 is the thickness of the O-ring, b is the depth of the chamfer at the groove opening, B2 is the effective depth of the O-ring groove, X is the depth into the groove when the second dart passes through the groove opening of the O-ring, Y is the distance from the center of the equivalent circular arc R to the line where U is located, R is the equivalent radius when the second dart passes through the groove opening of the O-ring, and W is the groove width of the O-ring.

[0075] An innovative method for forming a dart body includes the following steps:

[0076] Step 1: Based on the selected metal dart body base, such as... Figure 8 As shown, measure the outer diameter D1 of the dart head section, the outer diameter D2 of the metal dart body base, and the dart length La. At the same time, calibrate the axial radius Rn of the contact point and the base mating radius Rm=D1 / 2.

[0077] Step 2: Determine the basic dimensions of the flexible O-ring, such as... Figure 7 As shown, it includes the inner diameter A1 of the flexible O-ring, the axial width W1, and the radial thickness B1;

[0078] Step 3: Define the assembly layout area for the flexible O-rings on the metal dart body base, and reserve the location for the annular assembly groove;

[0079] Step 4: As Figure 9 As shown, the equivalent radius R of the collision contact arc is calculated based on the collision angle α between the two darts.

[0080]

[0081] Where Rn is the radius of the arc of the friction transition zone of the dart head section, α is the collision angle between the two darts, and Rm is the matrix mating radius;

[0082] Step 5: Based on the calculated equivalent arc radius R of the collision contact, use the critical groove depth calculation formula to solve for the critical groove depth B at which the flexible O-rings just make contact when the two darts collide.

[0083] ;

[0084] Where R is the equivalent radius of the collision contact arc, B1 is the radial thickness of the flexible O-ring, W is the width of the annular assembly groove, W=W1, and b is the depth of the groove chamfer (only used when the groove is designed with a chamfer).

[0085] Step 6: Select the interference amount between the annular assembly groove and the flexible O-ring assembly based on the product positioning:

[0086] Long service life: interference < 0, groove depth B is greater than the critical groove depth, there is an assembly gap between the flexible O-ring and the groove wall, and there is no squeezing wear upon collision;

[0087] Balancing lifespan and feel: 0.05mm≤interference≤0.1mm, balancing grip feel with the wear resistance and lifespan of the flexible O-ring;

[0088] Excellent handling: interference ≥0.1mm, flexible O-ring protrudes from the dart body surface, maximizing damping and anti-slip effect;

[0089] Step 7: Calculate the actual machining groove depth of the metal dart body by combining the critical groove depth B with the selected interference amount:

[0090] Actual machining groove depth = critical groove depth B - interference amount;

[0091] Step 8: Design the spacer ribs between the flexible O-rings, and control the width P of the spacer ribs within the range of 0.4mm-1mm;

[0092] Step 9: Based on the inner diameter A1 of the flexible O-ring, the axial width W1, the actual machining groove depth, and the width of the spacer ribs, form an annular assembly groove on the metal dart body substrate.

[0093] Step 10: Install the flexible O-ring onto the annular assembly groove of the metal dart body, thus completing the forming process of the entire dart body.

[0094] This invention provides three embodiments to illustrate the molding of dart bodies that have a long service life, a good service life and feel, and a good feel when used.

[0095] Example 1: Long service life (interference less than or equal to 0, with reserved assembly gap)

[0096] Design goals: To maximize the lifespan of flexible O-rings, prevent wear and tear on flexible O-rings during dart collisions, and achieve decorative effects through multi-color designs of flexible O-rings.

[0097] The specific implementation steps are as follows:

[0098] Step 1: Base Dimension Calibration

[0099] The target weight of the competitive standard dart is set at 22g, and the total length of the dart body is 51mm; the outer diameter of the front end of the dart head is D1=3.4mm, the outer diameter of the metal dart body base is D2=6.45mm, the axial radius of the contact point of the dart head is Rn=10mm, and the base fitting radius is Rm=D1 / 2=1.7mm.

[0100] Step 2: Determine the size of the flexible O-ring

[0101] The flexible O-ring is made of food-grade silicone, with an inner diameter of A1=5.25mm, an axial width of W1=2mm, and a radial thickness of B1=0.5mm.

[0102] Step 3: Positioning and marking of flexible O-rings

[0103] At 28mm from the center of the metal dart body, a 14.5mm axially wide annular assembly groove is evenly distributed in the grip buffer section, with all flexible O-rings concentrated in the area where the hand grips and bears the force.

[0104] Step 4: Calculate the equivalent circular arc R of the collision based on the parameters in Step 1.

[0105] According to the formula Calculate the actual R value, where α is the angle between the two darts at impact:

[0106] Set the collision limit angle between the two darts to α = 19°, and substitute it into the calculation formula to obtain the equivalent radius of the collision arc R = 9.51 mm.

[0107] Step 5: Calculation of critical trench depth B

[0108] According to the formula Calculate the critical groove depth B at which two darts just make contact upon impact.

[0109] Substituting the constants b=0mm, W=2mm, and B1=0.5 into the critical groove depth formula, the critical groove depth B=0.55mm is calculated. (Dimensional sectional view)

[0110] Step 6: Selection of Interference Quantity

[0111] To achieve non-extrusion protection of the flexible O-ring, an interference value of -0.06mm is selected. The negative value indicates that there is a uniform assembly gap of 0.06mm between the annular assembly groove of the metal dart body and the flexible O-ring, with no extrusion stress.

[0112] Step 7: Calculation of actual machining groove depth

[0113] Actual machining groove depth = B - interference amount = 0.55 - (-0.06) = 0.61mm, and the machining groove depth of the metal dart body base is uniformly set to 0.61mm.

[0114] Step 8: Spacing Reinforcement Structure Design

[0115] The spacing rib between two adjacent flexible grooves is P=0.5mm, which ensures the structural strength of the groove without compromising the smoothness of the grip.

[0116] Step 9: Based on the inner diameter A1=5.25mm, axial width W1=2mm, actual machining groove depth=0.61mm and the width P=1mm of the spacer rib, form an annular assembly groove on the metal dart body substrate.

[0117] Step 10: Install the flexible O-rings (alternating red, blue, and black colors) onto the annular assembly groove of the metal dart body, thus completing the molding process of the entire dart body. This ensures the service life while achieving a differentiated appearance.

[0118] The beneficial effects of this embodiment 1 are as follows:

[0119] 1. The flexible O-ring has a uniform gap with the annular assembly groove. When the dart is hit or when force is applied by hand, the flexible O-ring does not undergo continuous compression deformation. The aging and cracking rate of the flexible O-ring is greatly reduced, and the service life is increased by more than 60%.

[0120] 2. No forced interference fit assembly, flexible O-rings are easy to install and remove, different colors can be freely changed, and the product appearance has strong expandability.

[0121] 3. Upon collision, the impact force is buffered by the gap, and the metal body of the dart remains free from rigid impacts and scratches, ensuring the dart's appearance remains intact for a long time.

[0122] Example 2: Combining service life and feel (0.05mm≤interference≤0.1mm)

[0123] Design goal: To balance the wear resistance and lifespan of flexible O-rings with the feel of grip damping, adapting to professional daily training and general competitive scenarios in clubs, and balancing the three requirements of protection, feel, and appearance.

[0124] The specific implementation steps are as follows:

[0125] Steps 1-5 are the same as in Example 1;

[0126] Step 6: Selection of Interference Quantity

[0127] An interference value of 0.08mm was selected, which falls within the optimal balance range of 0.05mm to 0.1mm, balancing damping feel and wear resistance life.

[0128] Step 7: Calculation of actual machining groove depth

[0129] Actual machining groove depth = B - interference amount = 0.55 - 0.08 = 0.47 mm, and the uniform machining depth of the groove in the metal dart body is 0.47 mm.

[0130] Step 8: Spacing Reinforcement Structure Design

[0131] The spacing rib width P=0.5mm balances structural strength and grip smoothness.

[0132] Step 9: Based on the inner diameter A1=5.25mm of the flexible O-ring, the axial width W1=2mm, the actual machining groove depth=0.47mm and the width P=1mm of the spacer rib, form an annular assembly groove on the metal dart body substrate.

[0133] Step 10: Install the flexible O-ring (using a two-color symmetrical design) onto the annular assembly groove of the metal dart body, thus completing the molding process of the entire dart body. This achieves both longevity and a good feel, while also creating a distinctive decorative appearance.

[0134] Beneficial effects of Example 2

[0135] 1. 0.08mm micro-interference interference, the flexible ring slightly protrudes when holding the dart to form stable damping, the non-slip grip is clear, and the throwing force is not easy to slip;

[0136] 2. The interference amount does not exceed the upper limit of 0.1mm. The long-term extrusion deformation of the flexible O-ring is small. Under daily training scenarios, the wear resistance life of the flexible part meets the requirements of more than 12 months of use.

[0137] 3. The flexible O-ring absorbs the impact slightly upon impact, which avoids rigid impact damage to the metal dart body and prevents the grip from being loose due to excessive gaps, making it suitable for most competitive use scenarios.

[0138] Example 3: Strong tactile feedback (interference ≥ 0.1 mm)

[0139] Design goals: To maximize grip friction and damping feedback, adapt to high-intensity professional competitions and heavy throwing training scenarios, prioritize throwing feel, and be suitable for throwers with large force amplitude and prone to losing their grip.

[0140] The specific implementation steps are as follows:

[0141] Steps 1-5 are the same as in Example 1;

[0142] Step 6: Selection of Interference Quantity

[0143] An interference amount of 0.12mm was selected to achieve high-strength interference fit and maximize the height of the flexible O-ring protrusion.

[0144] Step 7: Calculation of actual machining groove depth

[0145] Actual machining groove depth = B - interference amount = 0.55 - 0.12 = 0.43 mm, and the machining depth of the groove in the metal dart body base is 0.43 mm.

[0146] Step 8: Spacing Reinforcement Structure Design

[0147] The width of the rib is P=0.5mm. The rib enhances the resistance of the groove to extrusion deformation and is suitable for high interference assembly stress.

[0148] Step 9: Based on the inner diameter A1=5.25mm, axial width W1=2mm, actual machining groove depth=0.43mm and the width P=1mm of the spacer rib, form an annular assembly groove on the metal dart body substrate.

[0149] Step 10: Install the flexible O-ring (colored rubber ring) onto the annular assembly groove of the metal dart body, thus completing the molding process of the entire dart body. This ensures the service life while achieving a differentiated appearance.

[0150] Beneficial effects of Example 3

[0151] 1. The 0.12mm high interference makes the flexible O-ring protrude significantly from the dart body surface, forming a continuous ring anti-slip damping band, which greatly improves the grip friction and completely prevents slippage during high-intensity throwing.

[0152] 2. The flexible O-ring buffers the impact of collisions, so there is no harsh metallic impact sound when multiple darts collide with the target, resulting in excellent noise reduction.

[0153] 3. Only a small portion of the lifespan of the flexible O-ring is sacrificed in exchange for an ultimate grip feel, specifically meeting the detailed needs of professional athletes in high-intensity competitions and specialized throwing training.

[0154] To facilitate improvements to the appearance of darts, grooves can be made on any component of the dart, such as the body, shaft, needle, or wing, and different colored rubber bodies can be embedded in the grooves.

[0155] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A dart body, comprising a metal dart body base and a plurality of flexible O-rings, wherein the metal dart body base is sequentially divided along its axial direction into a head section, a grip buffer section, and a tail section, characterized in that: The outer surface of the dart head section is a smooth arc surface. Several annular mounting grooves are evenly distributed along its axial direction at the grip buffer section. An integrally formed spacer rib is formed between two adjacent annular mounting grooves. The width of the spacer rib is 0.4-1mm. A flexible O-ring is installed in the annular mounting groove. The flexible O-ring protrudes from the annular mounting groove by 0.05-0.1mm.

2. The dart body according to claim 1, characterized in that: The flexible O-ring has a surface with raised or recessed patterns.

3. The dart body according to claim 1, characterized in that: The flexible O-ring is made of rubber or soft plastic.

4. A dart body according to claim 1, characterized in that: A chamfered structure is provided at the opening of the annular assembly groove.

5. A method for forming a dart body, characterized in that: This method for forming the dart body as described in any one of claims 1-3 includes the following steps: Step 1: Based on the selected metal dart body base, measure the outer diameter D1 of the front end of the dart head section, the outer diameter D2 of the metal dart body base, and the length La of the dart. At the same time, calibrate the axial radius Rn of the contact point and the base mating radius Rm=D1 / 2. Step 2: Determine the basic dimensions of the flexible O-ring, including the inner diameter A1, axial width W1, and radial thickness B1. Step 3: Define the assembly layout area for the flexible O-rings on the metal dart body base, and reserve the location for the annular assembly groove; Step 4: Calculate the equivalent radius R of the collision contact arc based on the collision angle α between the two darts; Step 5: Based on the calculated equivalent arc radius R of the collision contact, use the critical groove depth calculation formula to solve for the critical groove depth B at which the flexible O-ring just makes contact when the two darts collide. Step 6: Select the interference amount between the annular assembly groove and the flexible O-ring assembly based on the product positioning; Step 7: Calculate the actual machining groove depth of the metal dart body by combining the critical groove depth B with the selected interference amount; Step 8: Design the spacer ribs between the flexible O-rings, and control the width P of the spacer ribs within the range of 0.4mm-1mm; Step 9: Based on the inner diameter A1 of the flexible O-ring, the axial width W1, the actual machining groove depth, and the width of the spacer ribs, form an annular assembly groove on the metal dart body substrate. Step 10: Install the flexible O-ring onto the annular assembly groove of the metal dart body, thus completing the forming process of the entire dart body.

6. The method for forming a dart body according to claim 5, characterized in that: The formula for calculating the equivalent radius R of the collision contact circle based on the collision angle α between the two darts is as follows: Where Rn is the radius of the arc of the friction transition zone of the dart head section, α is the collision angle between the two darts, and Rm is the matrix mating radius.

7. The method for forming a dart body according to claim 5, characterized in that: The formula for calculating the critical trench depth is as follows: Where R is the equivalent radius of the collision contact arc, B1 is the radial thickness of the flexible O-ring, W is the width of the annular assembly groove, W=W1, and b is the depth of the groove chamfer.

8. The method for forming a dart body according to claim 5, characterized in that: The method for selecting the interference amount of the annular assembly groove and the flexible O-ring assembly based on product positioning is as follows: Long service life: interference < 0, groove depth B is greater than the critical groove depth, there is an assembly gap between the flexible O-ring and the groove wall, and there is no squeezing wear upon collision; Balancing lifespan and feel: 0.05mm≤interference≤0.1mm, balancing grip feel with the wear resistance and lifespan of flexible O-rings; Excellent handling: interference ≥0.1mm, flexible O-ring protrudes from the dart body surface, maximizing damping and anti-slip effect.

9. The method for forming a dart body according to claim 5, characterized in that: The formula for calculating the actual machining groove depth is: Actual machining groove depth = critical groove depth B - interference amount.

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