TW202402556A - Spoke reinforcing method and spoke reinforcing structure achieving the effects of reducing the chance of spoke fracture and prolonging the service life of a spoke - Google Patents

Abstract

This invention relates to a spoke reinforcing method and a spoke reinforcing structure. The spoke reinforcing method includes the following steps: preparing a spoke body with a head end portion and a threaded portion at two ends respectively; disposing a neck portion below the head end portion, wherein the neck portion is forged at least two times to increase a cross-sectional area of the neck portion and improve the density and the strength of metal grains therein; and forging a reinforcing structure in a form of a hexagonal column under the high-density neck portion, and absorbing a high-frequency lateral stress on a lower part of the high-density neck portion by utilizing characteristics of best compressive strength and bending strength of the hexagonal column. The spoke reinforcing structure fabricated by the method can achieve the effects of reducing the chance of spoke fracture and prolonging the service life of a spoke.

Description

A spoke strengthening method and spoke strengthening structure

The present invention relates to a method for strengthening spokes and manufacturing spokes with a strengthened structure. In other words, it refers to a method for strengthening spokes and a spoke strengthening structure that can increase the compression and bending strength of spokes, reduce the probability of breakage, and extend the service life.

Please refer to Figure 1. As shown in Figure 1, the traditional spoke (6) has a spoke body, and a head (61) and a threaded portion (62) are respectively provided at both ends of the spoke body, and the head (61) and A curved neck (63) is formed at the junction of the spoke bodies. Since the neck of traditional spokes often breaks during implementation, the industry began to improve it and developed a modified spoke (7), as shown in Figure 2 As shown, in addition to having the basic structure of the head (71), threaded portion (72) and neck (73) of the aforementioned spoke, a method is particularly proposed that uses at least two forgings at the neck (73) position of the spoke body. A unique forging processing method is used to improve the shortcoming that traditional spokes (6) often break at the neck (63). This modified spoke did perform quite successfully in tensile and fatigue tests, and the laboratory data was satisfactory. However, in actual use, unexplained fractures occasionally occur, and the fractures are almost always at the spokes on the non-driving side (N) of the rear wheel. This was a fatal flaw, and when this spoke broke it could jam the wheel, causing injury to the rider. However, it is abnormal for the spokes on the non-driving side (N) to break first, because this is the low-tension end (low-stress end). We know from experience that during use, the drive side (D) spokes that are subjected to high tension, high pulling force and high torsion should break first, as shown in Figure 3. Over the years, we have repeatedly conducted “tensile experimental tests” and “anti-fatigue experimental tests”. "Test", this kind of reinforced spoke can still obtain excellent data, but the cause of the fracture can only be dealt with as an unknown reason, and the case cannot be closed.

Why does the commonly used improved spoke (7) have good laboratory data, but fractures continue to occur? After tracing the cause, it was determined that the laboratory's testing method had a blind spot. The conventional tensile test (shown in Figure 4) and fatigue test (shown in Figure 5) of the modified spokes (7) are both vertical tests in which the force is applied straight up and down. However, whether the wheel set is in the process of assembling the wheel or in actual use, it will not only receive vertical force, but also lateral force. In particular, the spokes between the hub and the rim have an inclination angle. In order to obtain more accurate experimental data, the test method needs to be changed. Simulate the assembly method with different angles on both sides of the wheel. Different hubs are matched with different wheel diameters, which will approximately produce an inclination angle of about 4°~10° between the modified spokes and the hub (using a 26-inch bicycle rear wheel drive side of about 4° °, about 10° on the non-driving side). The tensile testing machine and fatigue testing machine were changed from the standard vertical angle test to the inclined angle and re-tested. In the new tensile test, the test results of the "inclined angle" and the "standard vertical angle" were compared, and it was found that the tensile strength of the improved spokes was The values vary little. When the improved spoke has an inclination angle of 10°, the tensile value only decreases by 1~2% (as shown in Figure 6). However, in the new fatigue test, comparing the test results of "tilt angle" and "standard vertical angle" (as shown in Figure 7), it was found that the life span of the spokes has great variation. Spokes are significantly more likely to break when they are tilted. When the spokes have an inclination angle of 10°, the fatigue test life drops by nearly 50%. It can be seen that this improved spoke processing method may be beneficial to low-speed but high-load vehicles (the spokes of this process have a high tensile value), but there is a high risk of breakage for high-speed vehicles (the spokes of this process are not conducive to high-frequency vibration fatigue). If not improved, improved spokes produced by this processing method will continue to cause accidents.

Further exploring this issue, we found through walking test and fatigue test that the habitual The fracture points of improved spokes mostly occur within 3mm directly below the forged strengthening area. However, after being assembled with the wheel set, and under normal tension of the modified spokes, observing the shape of the conventional modified spokes, it can be seen that there is stress bending (change in the direction of force) about 1~5mm directly below the forged strengthening area. This stressed bending point is where the bending stress is concentrated and is also the breaking point (B) of the fatigue test results (as shown in Figure 8). This breaking point (B) shows that the conventionally modified spoke uses forging to strengthen the neck. It does not deform due to work hardening (close to the steel body), but causes the direction of the force below to change, deform due to lateral force, and at high frequencies Under the vibration, fatigue hot zone/fracture hot zone is formed. The analysis of this fatigue hot zone/fracture hot zone is that at the junction of the forged strengthening zone and the non-forged zone of the modified spoke, the metal density is inconsistent, there are faults, and the grain interface is too different (as shown in Figure 9), causing bending Stress is concentrated in non-forged areas with lower metal density, reducing fatigue life.

In view of this, the inventor of this case is looking for a solution. Relying on the professional knowledge and manufacturing experience accumulated in manufacturing spokes for many years, through continuous experiments, trial production and improvements, he finally came up with the spoke strengthening method and spoke strengthening structure of the present invention to enhance the industrial efficiency. Competitiveness and added value.

The purpose of the present invention is to provide a method for strengthening spokes and a spoke strengthening structure, whereby an improved construction method is further proposed to address the shortcomings of conventional ordinary spokes or even strengthened improved spokes, in the fracture hot zone of the ordinary/improved spokes. According to the correct processing steps, a hexagonal cylindrical reinforced section is forged to replace the original cylindrical structure, and the fatigue fracture hot zone of the spoke must be avoided to obtain the best compressive strength and bending strength, and reduce the The fracture probability in the fatigue fracture hot zone achieves the effect of increasing the spoke life.

In order to achieve the above object, the present invention provides a method for strengthening spokes, the steps of which include: straightening and cutting, straightening and cutting the unprocessed spokes into required lengths; In the first forging, one end of the spoke is stamped by a first stamping unit to form an initial head and neck; in clamping forming, the head, neck and spoke body are assembled from the initially formed spoke using a clamping die. Clamping, while clamping and fixing, completes the shape forging of the reinforced part; for the second forging, a second stamping unit is used to punch the spokes fixed by the same clamping die to form a head and a neck. And the spoke reinforcement structure of the reinforced part; thread rolling, the above-mentioned spoke is thread rolled relative to the other end of the head to form a threaded part.

In one embodiment, a bending step can be added between the second forging and thread rolling steps to bend the neck of the formed spoke.

A spoke strengthening structure is produced based on the above spoke strengthening method. The spoke includes: a spoke body. One end of the spoke body is provided with a head, a neck, and a reinforcing part in order from the end edge, and the other end is provided with a threaded part.

In one embodiment, the length of the reinforced portion of the spoke reinforced structure is at least 5 mm.

In one embodiment, the cross-sectional shape of the reinforced portion is any of various polygons.

In one embodiment, the cross-sectional shape of the reinforced part is hexagonal.

In one embodiment, the cross-sectional shape of the reinforced portion is rectangular.

In one embodiment, the spoke patterns include straight pull spokes and elbow spokes.

Idiom:

(6):Traditional spokes

(61):Head

(62): Threaded part

(63):Neck

(7):Improved spokes

(71):Head

(72): Threaded part

(73):Neck

(D): Drive side

(N):Non-drive side

(B): Breaking point

The present invention:

(001): straight cut

(002):First forging

(003): clamping forming

(004):Second forging

(005):Bending

(006):Rolling teeth

(1):Spoke

(2):Head

(3): Neck

(4): Strengthening Department

(5): Threaded part

Figure 1 is a traditional spoke appearance.

Figure 2 shows the appearance of a conventional reinforced spoke.

Figure 3 is a schematic diagram of the conventional modified spokes installed on the wheel.

Figure 4 is a schematic diagram of a conventional modified spoke tensile test.

Figure 5 is a schematic diagram of a conventional modified spoke fatigue test.

Figure 6 is a schematic diagram of the tensile test of conventionally modified spokes with improved inclination angle.

Figure 7 is a schematic diagram of the fatigue test of conventionally modified spokes with improved inclination angle.

Figure 8 is a schematic diagram of the fracture point of a conventional improved spoke.

Figure 9 is a schematic diagram of the grain density of a conventional modified spoke.

Figure 10 shows the appearance of the spoke reinforcement structure of the present invention from different perspectives.

Figure 11 (A) (B) is a flow chart of the method for different spokes of the present invention.

Figure 12 (A) and (B) are schematic diagrams 1 and 2 of the actual manufacturing process of the spoke strengthening method for different spokes according to the present invention.

Figure 13 is a diagram showing an application example of the spoke strengthening method of the present invention.

Figure 14 is a schematic diagram of the grain density of the spoke reinforced structure of the present invention.

Figure 15 is a graph showing the fatigue test results of the reinforced spoke structure of the present invention, traditional general spokes, and conventional improved spokes at different tilt angles.

Please refer to Figures 10 to 14, which disclose a method for strengthening spokes in a preferred embodiment of the present invention. First, an elbow spoke drawn from a metal material into a required diameter is used as an example. The metal Materials include but are not limited to: stainless steel, carbon steel, titanium alloy, aluminum alloy, etc. The manufacturing method of the spokes includes straight-pull spokes and elbow spokes. Taking the manufacturing method of elbow spokes as an example, as shown in Figure 11 (B), the steps include: straight cutting (001), cutting the already drawn spokes. The shaped spokes (1) are straightened and cut to the required length; the first forging (002), One end of the spoke (1) is punched by a first stamping unit to form an initial head (2) and neck (3); clamping and forming (003) is performed, and the initially formed spoke (1) is formed using a The clamping die clamps the head (2), neck (3) and spoke (1) body, and completes the shape forging of the reinforced portion (4) while clamping and fixing. In this embodiment, a hexagonal column is used as an example ( It can also include but is not limited to: triangular prism, quadrilateral prism or any polygonal prism); second forging (004), and then use a second stamping unit to stamp the spokes (1) clamped by the clamp. To form the final head (2), neck (3) and reinforced part (4); bend (005), bend the neck (3) of the formed spoke (1); roll the teeth ( 006), roll the other end of the above-mentioned spoke (1) relative to the head (2) to form a threaded portion (5), thus completing a spoke reinforced structure, as shown in Figure 10.

As for the manufacturing method of straight-pull spokes, as shown in Figure 11 (A), the steps omit the bending (005) process, including: straight cutting (001), first forging (002), Clamping forming (003), second forging (004) and thread rolling (006).

The clamping forming (003) in the above reinforced spoke manufacturing method includes the second forging (004) process. It should be noted that the neck (3) and the reinforced part (4) of the spoke (1) must be in the same clamping mold Internal forging is completed to ensure that the crystal material density of the processed head (2), neck (3) and reinforced part (4) of the spoke (1) is continuous without faults, as shown in Figure 14.

Please refer to Figure 10. The spoke strengthening structure manufactured according to the above spoke strengthening method includes: a spoke (1) body, at one end of the spoke (1) body, a head (2) and a neck are arranged in sequence from the end edge. part (3) and reinforced part (4), and the other end is provided with a threaded part (5). In particular, the cross-sectional shape of the reinforced part (4) is hexagonal (or rectangular, or other polygonal shapes) Structural type, and experimentally proven to have the best compressive strength and bending strength while using the minimum amount of material.

Please refer to Figure 15 again, which discloses the fatigue test results chart of the spokes of the present invention, traditional spokes, and conventional improved spokes; the left side is the fatigue test (times), and PK below represents the traditional spoke, PSR represents the improved spoke, and PHR It is the spoke reinforced structure of the present invention. The left side of each bar diagram is 0 degrees (standard vertical fatigue test) and the right side is 10 degrees (oblique angle fatigue test). The same test conditions are used, the same raw material and the same production equipment are used. , the same testing equipment, the same set of fixtures, etc., were used to conduct fatigue tests (180Kgf, 10Hz) on traditional spokes, improved spokes and spoke reinforced structures; it can be clearly seen from the chart that the spoke reinforced structure of the present invention exhibits Data, whether it is 0 degrees (standard vertical fatigue test) or 10 degrees (tilt angle fatigue test), the performance is better than that of traditional spokes and conventional modified spokes. Through the support of experimental data, the weak points of conventional modified spokes can indeed be greatly improved after being modified into a hexagonal columnar reinforced part structure according to correct processing steps.

From the above description, it can be seen that the spoke strengthening method of the present invention is mainly aimed at the fatigue/fracture hot zone 1~3mm below the neck thickened by multiple forging processes. It is proposed to forge a reinforced portion ( Hexagonal cylinder or rectangular) are connected to each other to replace the conventional cylindrical spokes without forging at the joints. The reinforced part designed in this shape has the best compressive strength and bending strength characteristics to buffer the neck of high-density grains. It can reduce the high-frequency lateral stress on the connection below the spoke and improve the endless fracture accidents. At the same time, it can further reduce the probability of spoke fracture and increase the spoke life.

Although the present invention has been disclosed above through embodiments, it is not intended to limit the present invention. Anyone with ordinary skill in the art can, without departing from the spirit and scope of the present invention, Some modifications and embellishments may be made, so the protection scope of the present invention shall be defined by the appended patent application scope.

(1):Spoke

(2):Head

(3): Neck

(4): Strengthening Department

(5): Threaded part

Claims (8)

A spoke-strengthening method that includes the following steps: Straightening and cutting: Straighten and cut the extracted spokes to the required length; In the first forging, one end of the spoke is punched by a first stamping unit to form an initial head and neck; Clamping forming: use a clamping die to clamp the head, neck and spoke body of the initially formed spoke, and complete the shape forging of the reinforced part while clamping and fixing; For the second time, a second stamping unit is used to stamp the spokes clamped by the same clamp to form the final head, neck and reinforced part; Thread rolling: rolling the spokes relative to the other end of the head to form a threaded portion. In the spoke strengthening method described in claim 1, a bending step can be added between the second forging and thread rolling steps to bend the neck of the formed spoke. The spoke strengthening method according to claim 1, wherein the cross-sectional shape of the strengthening part is any one of polygons. The spoke strengthening method according to claim 1, wherein the cross-sectional shape of the strengthening part is hexagonal or rectangular. The spoke strengthening method of claim 1, wherein the length of the strengthening portion is at least 5 mm. A spoke reinforcement structure includes: a spoke body, a head, a neck and a reinforcement part are provided in order from the end edge at one end of the spoke body, and a threaded part is provided at the other end. The spoke reinforcement structure according to claim 6, wherein the cross-sectional shape of the reinforcement part is hexagonal or rectangular. The spoke reinforcement structure of claim 6, wherein the spoke type includes straight-pull spokes and elbow spokes.

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