A method for manufacturing a synchronizer thin-wall claw part

Abstract

The application discloses a preparation method of a synchronizer thin-wall claw part, which comprises the following steps: step one, material selection; step two, forging; step three, machining; and step four, heat treatment. The synchronizer thin-wall claw part is placed in a positioning fixture, the machined synchronizer thin-wall claw part is fixed in the working area of an inductor through the positioning fixture, alternating current is input into the inductor to generate an alternating magnetic field, and the surface temperature is increased; when the predetermined temperature is reached, the synchronizer thin-wall claw part is rapidly cooled to form a hardened layer, and quenching treatment is completed; the medium-carbon steel with a certain content of V, B and Ti elements is adopted to improve the hardenability of the material, the blowing cooling mode is adopted, the overall hardness of the part reaches the effect of quenching + high-temperature tempering treatment, and the quenching and tempering treatment process is reduced; through the back-to-back stacking type rotary induction process method, nine pawls are simultaneously inductively quenched, one-time induction quenching of two parts is realized, and the production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of machining technology, and specifically to a method for preparing a thin-walled claw-type part for a synchronizer. Background Technology

[0002] The company has developed a new three-cone synchronizer, which includes a thin-walled claw-like component in the assembly. A schematic diagram of the component is shown below. Figure 1 As shown, this synchronizer thin-walled claw part is generally a rotating part with nine pawls. The pawls are evenly or non-evenly distributed along the circumference in a certain proportion. The pawls have an irregular shape, with a width of 22mm and a thickness of only 2.5mm. To meet the requirements for wear resistance and strength of the pawl surface, this part is currently made of medium carbon alloy steel. The process is as follows: blanking—ring rolling—forging—quenching and tempering—rough machining—finish machining—nitriding—finish machining—finished product. This process uses forging, quenching and tempering, machining, and nitriding to ensure the strength and performance of the part, but it has the following drawbacks:

[0003] 1. The cost of raw materials is relatively high. An analysis of the cost of this part shows that raw materials account for 18%, which is a relatively high percentage.

[0004] 2. Forging and machining costs are high. The material blank is prone to overheating and burning during the forging process. Currently, forging is done by ring rolling and forging. The blank of the part cannot be forged to have 9 pawls, resulting in a large machining allowance and long time for subsequent machining.

[0005] 3. This material has high hardenability, and there is a risk of quenching cracks during the tempering process. Nitriding is a costly and time-consuming process.

[0006] These drawbacks have led to long processing cycles and high costs for this type of part. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for manufacturing thin-walled claw-type parts for synchronizers, thereby solving the problems of long processing cycle and high cost of such parts in the existing technology.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for preparing a thin-walled claw-type part for a synchronizer, comprising the following steps:

[0009] Step 1: Material Selection: Medium carbon steel with a C content of 0.37-0.49%, a Si content of 0.15-0.38%, and a Mn content of 0.90-1.40% is used. The medium carbon steel also contains V, B, and Ti, with V content of 0.05-0.20%, B content of 0.0001-0.0006%, and Ti content of 0.003-0.020%.

[0010] Step 2: Forging: Using the medium carbon steel from Step 1, the part blank is forged using a hot die forging press. Utilizing the residual heat after forging, the forged part blank is stacked in a staggered manner in a metal frame and transferred to the blank air cooling process. Subsequently, it is naturally cooled until room temperature. After rough turning and precision forging, the part blank after rough turning and precision forging is obtained.

[0011] Step 3: Machining: Machining the blanks of the parts after rough turning and precision forging in Step 2, without drilling holes, to obtain the synchronizer thin-walled claw parts to be heat treated.

[0012] Step 4: Heat Treatment: Perform heat treatment on the thin-walled claw-type parts of the synchronizer after machining in Step 3, specifically including:

[0013] Place the machined synchronizer thin-walled claw parts from step three into a positioning fixture. Fix the machined synchronizer thin-walled claw parts in the working area of ​​the sensor using the positioning fixture, ensuring that the gap between the parts and the sensor is 1.5-2.5mm. Pass an alternating current through the sensor to generate an alternating magnetic field, thereby generating an induced current inside the synchronizer thin-walled claw parts, causing the surface temperature to rise.

[0014] During the induction heating process, the synchronizer thin-walled claw parts are kept rotating by the positioning fixture. When the synchronizer thin-walled claw parts reach the predetermined temperature, they are quickly cooled by spraying quenching medium to form a hardened layer, thus completing the quenching process and obtaining the synchronizer thin-walled claw parts.

[0015] Step 5: Drilling:

[0016] Drill holes in the heat-treated synchronizer thin-walled claw parts obtained in step four to obtain synchronizer thin-walled claw parts.

[0017] The positioning fixture includes a positioning support platform and a cone handle installed on one side of the positioning support platform.

[0018] The positioning support platform includes a disc-shaped positioning support plate and a positioning support ring installed on one side of the positioning support plate.

[0019] The positioning support ring is circular, with one end mounted on the positioning support plate, and the diameter of the positioning support ring is smaller than the diameter of the positioning support plate.

[0020] A positioning support boss is formed between the outer edge of the positioning support plate and the positioning support ring.

[0021] The present invention also has the following technical features:

[0022] Step two specifically includes:

[0023] The part blank is forged using a hot forging press. The forging heating temperature is 1100-1300℃, and the blank is left with a 2-2.5mm allowance. The final forging temperature is 910-960℃. The forged part blanks are stacked in a staggered manner in a metal frame and then transferred to the blank air cooling process. In the blank air cooling process, a cold air fan is used to intermittently circulate air around the frame at a frequency of 20-60Hz for a cycle time of 160-200s. After the air cooling process is completed, the part temperature is 470-550℃. Then, it is transferred to natural cooling until room temperature.

[0024] The rough-machined blank has a allowance of 1-2mm, and then it is precision forged using a screw press. The end face allowance of the blank is 0.5-1mm, and the dimensions of the pawl part meet the requirements of the drawing, thus obtaining the part blank after rough machining and precision forging.

[0025] The upper surface of the positioning support boss is also provided with a slag storage tank with a width and depth of 2mm.

[0026] The positioning support plate is also provided with through holes.

[0027] Compared with the prior art, the present invention has the following technical effects:

[0028] (I) The present invention provides a method for preparing a thin-walled claw part of a synchronizer. It uses medium carbon steel with a certain amount of V, B and Ti elements added, which has the effect of improving the hardenability of the material. By using air cooling to cool the part, the overall hardness of the part reaches the effect of quenching + high temperature tempering treatment, reducing the tempering process in the production process of the part.

[0029] (II) This invention provides a method for manufacturing thin-walled claw-type parts for synchronizers. Through a rotary induction process, it achieves simultaneous induction hardening of nine claws and two parts simultaneously using one fixture. A 2-3mm thin aluminum alloy ring is placed between the back-to-back stacked parts on a positioning fixture to ensure uniform heating of the two parts during the 1-2 second induction process and uniform cooling during the 3-5 second quenching process. This improves production efficiency. The rotation of the parts during induction hardening ensures uniformity and consistency, improving product quality. The design of the positioning fixture makes part positioning more accurate and convenient, further improving operational efficiency. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a positioning fixture structure for a method of preparing a synchronizer thin-walled claw-type part according to the present invention.

[0031] Figure 2 This is a schematic diagram illustrating the specific process of the present invention.

[0032] Figure 3 This is a structural diagram of the thin-walled claw-type part of the synchronizer manufactured according to the present invention.

[0033] The meanings of the labels in the attached diagram are as follows:

[0034] 1-Positioning support platform, 2-Conical shank, 3-Through hole, 4-Thin-walled claw-like part of synchronizer to be quenched, 5-Circular sensor, 6-Quenching fluid pipeline, 7-Cooling water pipeline.

[0035] 1-1-Positioning support plate, 1-2-Positioning support ring, 1-3-Positioning support boss, 1-4-Slag storage tank.

[0036] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0037] Unless otherwise specified, all components in this invention are components known in the prior art.

[0038] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0039] Example 1:

[0040] This embodiment provides a method for manufacturing a thin-walled claw-type part for a synchronizer, including the following steps:

[0041] Step 1: Material Selection: Medium carbon steel with a C content of 0.37-0.49%, a Si content of 0.15-0.38%, and a Mn content of 0.90-1.40% is used. The medium carbon steel also contains V, B, and Ti, with V content of 0.05-0.20%, B content of 0.0001-0.0006%, and Ti content of 0.003-0.020%.

[0042] Step 2: Forging: Using the medium carbon steel from Step 1, the part blank is forged using a hot die forging press. Utilizing the residual heat after forging, the forged part blank is stacked in a staggered manner in a metal frame and transferred to the blank air cooling process. Subsequently, it is naturally cooled until room temperature. After rough turning and precision forging, the part blank after rough turning and precision forging is obtained.

[0043] Step 3: Machining: Machining is performed on the blank parts after rough turning and precision forging in Step 2, including machining the end face and internal cone, etc. Drilling is not performed at this time, to obtain the synchronizer thin-walled claw parts to be heat treated.

[0044] Step 4: Heat Treatment: Perform heat treatment on the thin-walled claw-type parts of the synchronizer to be heat-treated in Step 3, specifically including:

[0045] Place the machined synchronizer thin-walled claw parts from step three into a positioning fixture. Fix the machined synchronizer thin-walled claw parts in the working area of ​​the sensor using the positioning fixture, ensuring that the gap between the parts and the sensor is 1.5-2.5mm. Pass an alternating current through the sensor to generate an alternating magnetic field, thereby generating an induced current inside the synchronizer thin-walled claw parts, causing the surface temperature to rise.

[0046] During the induction heating process, the synchronizer thin-walled claw parts are kept rotating by the positioning fixture. When the synchronizer thin-walled claw parts reach the predetermined temperature, they are quickly cooled by spraying quenching medium to form a hardened layer, thus completing the quenching process and obtaining the synchronizer thin-walled claw parts.

[0047] The heating time for the thin-walled claw-type parts of the synchronizer is 1-3 seconds, and the quenching medium spraying time is 3-5 seconds, based on a frequency of 200-250kHz.

[0048] Step 5: Drilling:

[0049] Drill holes in the heat-treated synchronizer thin-walled claw-like parts obtained in step four to obtain synchronizer thin-walled claw-like parts, such as... Figure 3 As shown.

[0050] If the hole is drilled before step four, the induction hardening process will cause thermal effects on the hole, resulting in hole shrinkage. By machining the hole after step four, the hole dimensions can be fully guaranteed.

[0051] like Figure 1 As shown, the positioning fixture includes a positioning support platform 1 and a cone handle 2 installed on one side of the positioning support platform 1.

[0052] The positioning support platform 1 includes a disc-shaped positioning support plate 1-1 and a positioning support ring 1-2 installed on one side of the positioning support plate 1-1.

[0053] The positioning support ring 1-2 is circular, with one end mounted on the positioning support plate 1-1, and the diameter of the positioning support ring 1-2 is smaller than the diameter of the positioning support plate 1-1.

[0054] A positioning support boss 1-3 is formed between the outer edge of the positioning support plate 1-1 and the positioning support ring 1-2.

[0055] Adding a certain amount of V, B and Ti elements to medium carbon steel can improve the hardenability of the material. By using air cooling to cool the parts, the overall hardness of the parts can achieve the effect of quenching + high temperature tempering treatment, reducing the tempering process in the parts production process.

[0056] In application, the synchronizer thin-walled claw-like parts machined in step three are fitted onto the outside of the positioning support ring 1-2 and placed on the positioning support boss 1-3. The fitting gap is 0.04-0.10mm. This ensures that the parts are smoothly and stably placed into the fixture during the production process, and also ensures that the parts can rotate smoothly during induction hardening without eccentric shaking.

[0057] The taper shank 2 has a Morse taper of 3#, which facilitates connection with the machine tool motor drive. The fit is an interference fit. The drive device drives the taper shank 2 to rotate, thereby rotating the part.

[0058] This invention can also achieve the simultaneous processing of two synchronizer thin-walled claw parts by attaching two machined synchronizer thin-walled claw parts to the outside of the positioning support ring 1-2. By adjusting the height of the inductor and the placement of the parts, the two parts are stacked back to back, with a thin aluminum alloy ring with the same inner and outer diameters as the end face ring of the parts and a thickness of 2-3 mm placed between the two parts. This ensures uniform induction heating and quenching cooling of the parts' pawls within a short time, enabling simultaneous induction quenching of both parts. The ratio of the inductor height to the pawl thickness, h / a, is 2.2-2.6.

[0059] As a preferred embodiment:

[0060] Step two specifically includes:

[0061] The part blank is forged using a hot forging press. The forging heating temperature is 1100-1300℃, and the blank is left with a 2-2.5mm allowance. The final forging temperature is 910-960℃. Using the residual heat after forging, the forged part blanks are stacked in a staggered manner in a metal frame and then transferred to the blank air cooling process. In the blank air cooling process, a cold air fan is used to intermittently circulate air around the frame at a frequency of 20-60Hz for a cycle time of 160-200s. After the air cooling process is completed, the part blank temperature is 470-550℃. Subsequently, it is transferred to natural cooling until room temperature.

[0062] After the above steps, the hardness range of the part blank is 240-280 HB. The metallographic structure of the part blank after residual heat pretreatment should be pearlite + network ferrite + a small amount of intragranular ferrite, with no continuous ferrite bands allowed, and the width not exceeding 60 μm. If discontinuous ferrite bands are present, the width should not exceed 70 μm. This process ensures both the hardness and metallographic structure of the part, while also reducing the processing cost of the blank pretreatment.

[0063] The rough-machined blank has a allowance of 1-2mm, and then it is precision forged using a screw press. The end face allowance of the blank is 0.5-1mm, and the dimensions of the pawl part meet the requirements of the drawing, thus obtaining the part blank after rough machining and precision forging.

[0064] As a preferred embodiment:

[0065] The upper surface of the positioning support boss 1-3 is also provided with a slag storage trough 1-4 with a width and depth of 2mm.

[0066] The positioning support plate 1-1 is also provided with a through hole 3.

[0067] The purpose of the slag collection tanks 1-4 is to collect the small impurities of the parts into the tanks, which facilitates collection and prevents the small impurities from affecting the positioning of the parts.

[0068] The positioning support plate 1-1 also has 5 through holes 3, which not only reduces weight but also facilitates water drainage during the production process and makes it easier to place parts and more accurate in positioning.

[0069] like Figure 2 As shown, in order to ensure the flow rate and pressure of the quenching medium sprayed onto the surface of the part during quenching, two sets of quenching fluid pipelines 6 are designed on the upper end face of the annular sensor 5. The quenching fluid pipelines 6 are symmetrically distributed in a circumferential direction of 180°.

[0070] After the part is heated, quenching liquid is injected into the two quenching liquid pipelines 6 at the same time. The quenching liquid quickly fills the inductor cavity. The inner wall of the circular inductor 5 has three rows of water spray holes with a diameter of 1-3 mm, which are evenly arranged at an angle of 45° and horizontally spaced 2-3 mm. The quenching liquid is instantly sprayed onto the nine pawl parts to ensure the quenching effect.

[0071] The quenching fluid concentration is 1-3%. Selecting this concentration range ensures the quenching effect of the parts, achieving a hardness value of over 55 HRC and a certain depth of hardened layer. On the other hand, it reduces the deformation of the pawl part and prevents the parts from cracking during quenching.

[0072] Two sets of cooling water pipes 6 are also designed on the upper surface of the circular sensor 5 for cooling the circular sensor 5.

[0073] For this type of part, equipment with a frequency of 200-250kHz and a power of 60-100KW was selected. A rotary induction hardening process was used to achieve simultaneous induction hardening of nine pawls, and two parts could be induction hardened at a time. The induction heating time was 1-3 seconds, and the quenching water spray time was 3-5 seconds, improving production efficiency. The rotation of the part during induction hardening ensured uniformity and consistency, improving product quality. The design of the positioning fixture made part positioning more accurate and convenient, further improving operational efficiency.

[0074] During the part placement process, one part is placed first, followed by another in the opposite direction, so that the two parts are stacked back-to-back. Crucially, a thin aluminum alloy ring with the same inner and outer diameters as the end face ring of the first part and a thickness of 2-3 mm is placed on its upper surface. This ring improves the heating efficiency and heat uniformity of the parts, preventing localized heating obstruction between the two parts within a short period (1-3 seconds). It also improves the cooling uniformity during the quenching process. This allows for the processing of two parts at once, doubling production efficiency.

[0075] The manufactured parts were inspected, and the hardened layer depth, surface hardness, metallographic structure, and dimensions all met the product requirements.

[0076]

[0077] The above technical solutions are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived by those skilled in the art within the scope of the technology disclosed in the present invention without creative effort are covered within the scope of protection of the present invention.

Claims

1. A method of manufacturing a synchronizer thin-wall pawl type part, characterized by, Includes the following steps: Step 1: Material Selection: Medium carbon steel with a C content of 0.37-0.49%, a Si content of 0.15-0.38%, and a Mn content of 0.90-1.40% is used. The medium carbon steel also contains V, B, and Ti, with V content of 0.05-0.20%, B content of 0.0001-0.0006%, and Ti content of 0.003-0.020%. Step 2: Forging: Using the medium carbon steel from Step 1, the part blank is forged using a hot die forging press. Utilizing the residual heat after forging, the forged part blank is stacked in a staggered manner in a metal frame and transferred to the blank air cooling process. Subsequently, it is naturally cooled until room temperature. After rough turning and precision forging, the part blank after rough turning and precision forging is obtained. Step 3: Machining: Machining is performed on the blanks of the parts after rough turning and precision forging in step two, without drilling, to obtain the synchronizer thin-walled claw parts to be heat treated; Step Four: Heat treatment: The thin-walled claw-type parts of the synchronizer to be heat-treated in step three are subjected to heat treatment, specifically including: The machined synchronizer thin-walled claw parts from step three are placed in a positioning fixture. The positioning fixture is used to fix the machined synchronizer thin-walled claw parts in the working area of ​​the sensor, ensuring that the gap between the parts and the sensor is 1.5-2.5mm. An alternating current is passed through the sensor to generate an alternating magnetic field, thereby generating an induced current inside the synchronizer thin-walled claw parts, which raises the surface temperature. During the induction heating process, the synchronizer thin-walled claw parts are kept rotating by the positioning fixture. When the synchronizer thin-walled claw parts reach the predetermined temperature, they are quickly cooled by spraying quenching medium to form a hardened layer, thus completing the quenching treatment and obtaining the heat-treated synchronizer thin-walled claw parts. Step 5: Drilling: Drill holes in the heat-treated synchronizer thin-walled claw parts obtained in Step 4 to obtain synchronizer thin-walled claw parts. The positioning fixture includes a positioning support platform (1) and a cone handle (2) installed on one side of the positioning support platform (1). The positioning support platform (1) includes a disc-shaped positioning support plate (1-1) and a positioning support ring (1-2) installed on one side of the positioning support plate (1-1). The positioning support ring (1-2) is circular, with one end mounted on the positioning support plate (1-1), and the diameter of the positioning support ring (1-2) is smaller than the diameter of the positioning support plate (1-1). A positioning support boss (1-3) is formed between the outer edge of the positioning support plate (1-1) and the positioning support ring (1-2). Step two specifically includes: The part blank is forged using a hot die forging press. The forging heating temperature is 1100-1300℃, and the part blank is reserved with a 2-2.5mm allowance. The final forging temperature is 910-960℃. The forged part blanks are stacked in a staggered manner in a metal frame and then transferred to the blank air cooling process. In the blank air cooling process, a cold air fan is used to intermittently circulate air around the frame at a frequency of 20-60Hz and a circulation time of 160-200s. After the air cooling process is completed, the part temperature is 470-550℃. Then, it is transferred to natural cooling until room temperature. The rough-machined blank has a allowance of 1-2mm, and then it is precision forged using a screw press. The end face allowance of the blank is 0.5-1mm, and the dimensions of the pawl part meet the requirements of the drawing, thus obtaining the part blank after rough machining and precision forging.

2. The method for manufacturing a synchronizer thin-walled claw-like part as described in claim 1, characterized in that, The upper surface of the positioning support boss (1-3) is also provided with a slag storage trough (1-4) with a width and depth of 2mm. The positioning support plate (1-1) is also provided with a through hole (3).

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