Cam piece and heat treatment method thereof

Abstract

The invention relates to a cam piece and a heat treatment method thereof. The heat treatment method of the cam piece comprises the following steps: a temperature rising stage: rising the furnace temperature to a quenching temperature, and controlling the carbon potential in the furnace to be a first preset value; a loading stage: hoisting the to-be-treated cam sheet and then loading into a furnace; a heat preservation stage: raising the furnace temperature to the quenching temperature after charging, controlling the carbon potential to be a first preset value, and carrying out heat preservation treatment for a first preset time; quenching stage: carrying out static oil quenching on the to-be-treated cam sheet for a second preset time by adopting quenching oil of which the initial temperature is the first preset temperature, and controlling the oil outlet temperature of the to-be-treated cam sheet to be the second preset temperature, so as to obtain the heat-treated cam sheet; the second preset temperature is higher than the first preset temperature. The invention further provides the cam piece obtained through the heat treatment method. The heat treatment method solves the problem that an existing heat treatment method of the cam piece easily causes deformation of the cam piece, and meanwhile it is guaranteed that the hardness of the cam piece meets the set requirement.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment, and in particular to a cam piece and a heat treatment method thereof. Background Art

[0002] The cam is a key component in a mechanical transmission system. It controls the timing and movement of the mechanical movement by contacting the follower. In automated production equipment, the cam can control the movement trajectory of the robot arm to achieve accurate grabbing and placement of materials. The cam has good wear resistance and high strength and can withstand high impact and pressure. In order to improve the performance of the cam, heat treatment methods such as carburizing and quenching are usually used to enhance its surface hardness, wear resistance and corrosion resistance. However, during the heat treatment process, due to organizational changes, parts are prone to deformation after heat treatment. In order to ensure the stability of product quality and reduce deformation after heat treatment, a processing method that can effectively control the heat treatment deformation of the cam is urgently needed. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a cam piece and a heat treatment method thereof to solve the problem that the existing heat treatment method of the cam piece is prone to cause deformation of the cam piece, while ensuring that the hardness of the cam piece meets the set requirements and improving the stability of the cam piece quality.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A heat treatment method for a cam piece comprises the following steps:

[0006] Heating stage: the furnace temperature is raised to the quenching temperature, and the carbon potential control range in the furnace is the first preset value;

[0007] Loading stage: hoist the cam pieces to be processed and load them into the furnace;

[0008] Insulation stage: after loading the furnace, the furnace temperature is raised to the quenching temperature, the carbon potential control range is the first preset value, and the insulation treatment is performed for the first preset time;

[0009] Quenching stage: using quenching oil with a starting temperature of a first preset temperature to perform static oil quenching on the cam piece to be processed for a second preset time, controlling the oil outlet temperature of the cam piece to be processed to be the second preset temperature, and obtaining a cam piece after heat treatment;

[0010] The second preset temperature is greater than the first preset temperature.

[0011] According to the above technical means, by raising the furnace temperature to the quenching temperature before loading the furnace, it is effectively ensured that the cam piece to be processed can be heated up in time after loading the furnace, thereby avoiding the increase of the heating time of the parts due to too slow heating, thereby increasing the "self-weight deformation" of the parts during the heating process; by adopting a hoisting method to clamp the cam piece to be processed, it is effectively ensured that the cam piece to be processed can be cooled evenly and quickly during the quenching stage, and at the same time, it is avoided that the product is damaged when the furnace is loaded; by performing insulation treatment on the cam piece to be processed, the uniformity of the heating of the parts is effectively guaranteed, and the thermal stress deformation of the parts during the quenching process is reduced; by using static oil quenching to uniformly quench the cam piece to be processed, the deformation of the cam piece to be processed during the re-quenching process is greatly reduced.

[0012] Among them, the furnace temperature raising and the cam piece to be processed can be hoisted at the same time. By adding methanol and combining equipment instrument monitoring, the carbon potential in the furnace can be accurately controlled.

[0013] After long-term research and analysis, the inventors of this case found that the main factors affecting the deformation of the cam plate during heat treatment are: 1) Heating temperature: If the heating temperature is too high, the proportion of each phase in the steel will change greatly, the thermal stress and structural stress will increase, and it is easy to cause deformation of the parts; 2) Cooling speed: If the cooling speed is too fast, the uneven cooling of the surface and core of the part will increase, and the generated thermal stress and structural stress will also increase, resulting in aggravated deformation. If the cooling speed is too slow, the hardness of the part may be insufficient or the expected quenching effect may not be achieved; 3) Quenching method: Quenching methods such as vertical quenching and preset quenching have an impact on the deformation of the parts. Reasonable quenching methods can make the parts more evenly heated and cooled during the quenching process and reduce deformation. Therefore, choosing appropriate process methods, clamping methods and cooling methods is a key technology to control the deformation of the cam plate.

[0014] Based on long-term related experiments, comparative tests were carried out with different quenching temperatures, holding times, quenching methods and clamping methods to obtain the heat treatment method for the cam piece of the present invention, which solves the problem of large deformation of the existing cam piece after heat treatment, and controls the deformation of the part to less than 0.4mm, which fully meets the technical requirements.

[0015] Preferably, the quenching temperature is 790°C to 805°C.

[0016] Preferably, the quenching temperature is 795°C.

[0017] Experiments have shown that by precisely controlling the quenching temperature, the proportion changes of each phase, thermal stress and structural stress can be effectively reduced, thereby ensuring the hardness of the parts after heat treatment.

[0018] Preferably, the first preset value is 0.6-0.8%.

[0019] Preferably, the furnace loading time is within 5 minutes.

[0020] Preferably, the hoisting method is vertical hoisting, and the hoisting interval between adjacent cam pieces to be processed is 120-180 mm.

[0021] By cleverly adopting a vertical hoisting method to clamp the cam pieces to be processed and cleverly controlling the hoisting spacing of adjacent cam pieces to be processed, it is effectively ensured that the cam pieces to be processed can be cooled quickly and evenly during the re-quenching stage, while avoiding damage to the product when it is loaded into the furnace, thereby effectively ensuring the various performances of the cam pieces after heat treatment.

[0022] Preferably, the first preset time is 40 minutes to 60 minutes.

[0023] Experiments have proven that by cleverly controlling the duration of the insulation phase, the problem of "self-weight deformation" of parts can be effectively avoided and part deformation can be minimized.

[0024] Preferably, the first preset time is 50 minutes.

[0025] Preferably, the first preset temperature is 60°C to 80°C.

[0026] Preferably, the quenching oil needs to be stirred for 2 to 3 minutes before quenching.

[0027] Experiments have shown that stirring the quenching oil for 2 to 3 minutes before quenching can effectively ensure the uniformity of the quenching oil temperature, thereby achieving uniform quenching of the cam piece to be processed.

[0028] Preferably, the second preset time is 15 to 20 minutes.

[0029] Preferably, the second preset temperature is 80°C to 110°C.

[0030] By precisely controlling the oil outlet temperature of the cam piece to be processed, it is ensured that the parts are fully quenched while not being completely cooled, thereby effectively controlling the quenching deformation of the parts and ensuring the surface hardness of the parts after quenching.

[0031] Preferably, the composition content of the cam plate includes, by mass percentage: 0.17% to 0.23% carbon (C), 0.17% to 0.37% silicon (Si), 0.60% to 0.95% manganese (Mn), ≤0.035% sulfur (S), ≤0.035% phosphorus (P), 0.40% to 0.70% chromium (Cr), 0.35% to 0.75% nickel (Ni), 0.20% to 0.30% molybdenum (Mo) and ≤0.30 copper (Cu). It is commonly known as 20CrNiMo cam plate.

[0032] The present invention also provides a cam piece processed by the heat treatment method of the present invention.

[0033] Preferably, the hardness of the cam piece is 58-61HRC, and the deformation of the cam piece is ≤0.4mm.

[0034] Preferably, the deformation of the cam piece is ≤0.2 mm.

[0035] Beneficial effects of the present invention:

[0036] The heat treatment method of the cam piece of the present invention can make the parts more evenly heated and cooled during the quenching process and reduce deformation by cleverly setting the furnace loading method. By cleverly controlling the time of the heat preservation stage, the problem of "self-weight deformation" of the parts is effectively avoided, and the deformation of the parts is reduced to the greatest extent. By cleverly controlling the various process parameters in the quenching stage, the proportion change of each phase, thermal stress, quenching stress and tissue stress are effectively reduced, thereby reducing the deformation of the parts after quenching. The hardness and deformation of the processed cam piece meet the product quality requirements, and the stability of the cam piece quality is effectively improved.

[0037] The cam piece of the present invention has been tested to have a deformation of ≤0.4mm after quenching and a surface hardness of 58-62HRC, which fully meets the process requirements of the cam piece, thereby broadening the application of the cam piece and having promotion and application value in the field of cam piece heat treatment technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a physical picture of the cam piece hoisting;

[0039] Figure 2 This is a physical picture of the cam piece after heat treatment;

[0040] Figure 3 It is a structural schematic diagram of the existing cam piece after heat treatment;

[0041] Figure 4 is a cross-sectional view of a cam piece after existing heat treatment;

[0042] Among them, 1-cam piece, 2-deformation part. DETAILED DESCRIPTION

[0043] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0044] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0045] The present invention intends to disclose a cam piece and a heat treatment method thereof, so as to solve the problem that the existing heat treatment method of the cam piece easily causes the cam piece to deform, while ensuring that the hardness of the cam piece meets the set requirements.

[0046] A heat treatment method for a cam piece includes the following steps:

[0047] Heating stage: the furnace temperature is raised to the quenching temperature, and the carbon potential control range in the furnace is the first preset value;

[0048] Loading stage: hoist the cam pieces to be processed and load them into the furnace; the cam pieces to be processed should be loaded into the furnace evenly, the loading spacing should be precisely controlled, the number of pieces loaded into each furnace should be ≤13 pieces, and the product is clamped by hoisting; this stage mainly ensures that the parts can be cooled evenly and quickly during the quenching stage, and at the same time ensures that there are no bumps when the products are loaded into the furnace; the furnace should be loaded quickly, the loading time should be controlled within 5 minutes, and the parts should be heated up in time after loading;

[0049] Insulation stage: after loading the furnace, the furnace temperature is raised to the quenching temperature, the carbon potential control range is the first preset value, and the insulation treatment is performed for the first preset time;

[0050] Quenching stage: using quenching oil with a starting temperature of a first preset temperature to perform static oil quenching on the cam piece to be processed for a second preset time, controlling the oil outlet temperature of the cam piece to be processed to be the second preset temperature, and obtaining a cam piece after heat treatment;

[0051] The second preset temperature is greater than the first preset temperature.

[0052] By raising the furnace temperature to the quenching temperature before loading the furnace, it is effectively ensured that the cam piece to be processed can be heated up in time after loading the furnace, thereby avoiding the increase of the heating time of the parts due to too slow heating, thereby increasing the "self-weight deformation" of the parts during the heating process; by adopting the hoisting method to clamp the cam piece to be processed, it is effectively ensured that the cam piece to be processed can be cooled evenly and quickly during the quenching stage, and at the same time, it is avoided that the product is damaged when loading the furnace; by heat-insulating the cam piece to be processed, the uniformity of the heating of the parts is effectively guaranteed, and the thermal stress deformation of the parts during the quenching process is reduced; by adopting the static oil quenching method to uniformly quench the cam piece to be processed, the deformation of the cam piece to be processed during the re-quenching process is greatly reduced.

[0053] Among them, the furnace temperature raising and the cam piece to be processed can be hoisted at the same time. By adding methanol and combining equipment instrument monitoring, the carbon potential in the furnace can be accurately controlled.

[0054] The influence of clamping on quenching deformation: After many quenching tests, it was found that the clamping method, clamping position and number of clamping parts have a certain influence on the quenching deformation of parts. Implementation of the plan: (1) Clamping method: After process test verification, the method of hoisting parts is the clamping method with the smallest deformation, while the deformation of other clamping methods (such as horizontal placement or vertical placement on the tooling) is greater than hoisting. Therefore, during the loading process, the parts are hoisted by wire, and the fixed position of the wire must be the base circle of the cam piece. (2) Clamping position: The test found that the cooling rate of the outer ring of the cam piece is inconsistent with the cooling rate of the inner ring, resulting in the deformation of the outer ring of the cam piece being inconsistent with the deformation of the inner ring, thereby affecting the consistency of the product. Therefore, after many tests, the spacing between adjacent parts during part hoisting can be accurately controlled to effectively reduce the difference in cooling rate between the outer and inner rings of the parts. (3) Loading quantity: For commonly used furnaces, it is best to load 9 to 13 parts. If too many parts are loaded, uneven quenching or too fast cooling will inevitably occur, resulting in uneven quenching of parts and increased deformation of parts. The main purpose of optimizing the number of parts loaded is to improve the uniformity of part quenching, make the cooling speed of parts almost consistent, and take into account the deformation of parts.

[0055] Change the quenching method of parts: mainly change the cooling method of parts, change "oil cooling stirring" to "static oil" cooling, which can reduce the cooling speed of parts to a certain extent, thereby reducing the deformation of parts.

[0056] The specific implementation method is: modify the process to adjust the cooling method to static oil quenching; during the test quenching process, before the parts enter the oil for cooling, turn off the compressed air, then enter the parts into the oil, and cool the parts in the quenching oil for 15 to 20 minutes. Measure the surface temperature of the parts after they are out of the oil. The surface temperature of the parts should be ≤110°C. This can ensure that the parts are fully quenched and control the parts from being completely cooled, thereby effectively controlling the quenching deformation of the parts.

[0057] In some embodiments, the quenching temperature is 790°C to 805°C.

[0058] Exemplarily, the quenching temperature is 795°C.

[0059] In some embodiments, the first preset value is 0.6-0.8%.

[0060] In some embodiments, the time to load the furnace is within 5 minutes.

[0061] Exemplarily, the hoisting method is vertical hoisting, and the hoisting interval between adjacent cam pieces to be processed is 120 to 180 mm.

[0062] By cleverly adopting a vertical hoisting method to clamp the cam pieces to be processed and cleverly controlling the hoisting spacing of adjacent cam pieces to be processed, the difference in cooling speed between the outer and inner rings of the parts is effectively reduced, effectively ensuring that the cam pieces to be processed can be cooled quickly and evenly during the re-quenching stage, while avoiding damage to the product when it is loaded into the furnace, thereby effectively ensuring the various performances of the cam pieces after heat treatment.

[0063] In some embodiments, in order to avoid the problem of "self-weight deformation" of parts and minimize deformation of parts, the first preset time is controlled to be 40 minutes to 60 minutes.

[0064] Exemplarily, the first preset time is 50 minutes.

[0065] In some embodiments, the first preset temperature is 60°C to 80°C.

[0066] In some embodiments, in order to ensure the uniformity of the quenching oil temperature and thus achieve uniform quenching of the cam piece to be processed, the quenching oil needs to be stirred for 2 to 3 minutes before quenching.

[0067] In some embodiments, the second preset time is 15 to 20 minutes.

[0068] In some embodiments, the second preset temperature is 80°C to 110°C.

[0069] In some embodiments, the composition content of the cam plate includes, by mass percentage: 0.17% to 0.23% carbon (C), 0.17% to 0.37% silicon (Si), 0.60% to 0.95% manganese (Mn), ≤0.035% sulfur (S), ≤0.035% phosphorus (P), 0.40% to 0.70% chromium (Cr), 0.35% to 0.75% nickel (Ni), 0.20% to 0.30% molybdenum (Mo) and ≤0.30% copper (Cu). It is commonly known as 20CrNiMo cam plate.

[0070] In some embodiments, a cam piece processed by the heat treatment method of any of the above embodiments is also provided.

[0071] Among them, through test determination, the hardness of the cam piece processed by the above heat treatment method is 58-61HRC, and the deformation of the cam piece is ≤0.4mm. Among them, the hardness requirement for the cam piece in the actual production process is 58-62HRC.

[0072] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the heat treatment method of the cam piece of the present invention will be further described in detail below in combination with specific embodiments and drawings. Obviously, the specific embodiments described are only part of the embodiments of the present application, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation to the present application and its application. Based on the specific embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present application.

[0073] If no specific techniques or conditions are specified in the specific embodiments, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0074] Example 1

[0075] A heat treatment method for a 20CrNiMo cam sheet comprises the following steps:

[0076] S1, heating stage: the furnace temperature is raised to the quenching temperature of 790°C, and the carbon potential in the furnace is controlled in the range of 0.6-0.8%;

[0077] S2, loading stage: hoist the cam pieces to be processed, the spacing between adjacent cam pieces to be processed is between 120 and 180 mm, and the furnace is loaded after hoisting. The number of pieces loaded in each furnace should be ≤ 13. The actual picture after hoisting is as follows Figure 1 As shown;

[0078] S3, insulation stage: after loading the furnace, the furnace temperature is raised to 790°C, the carbon potential is controlled between 0.6 and 0.8%, and the insulation treatment is carried out for 50 minutes;

[0079] S4, quenching stage: stir the quenching oil for 3 minutes, then use the quenching oil with a starting temperature of 70°C to perform static oil quenching on the cam piece to be treated for 16 minutes, control the oil outlet temperature of the cam piece to be treated to be 100°C, and obtain the cam piece after heat treatment, such as Figure 2 shown.

[0080] Example 2

[0081] A heat treatment method for a 20CrNiMo cam sheet comprises the following steps:

[0082] S1, heating stage: the furnace temperature is raised to the quenching temperature of 795°C, and the carbon potential in the furnace is controlled in the range of 0.6-0.8%;

[0083] S2, loading stage: hoist the cam pieces to be processed, the spacing between adjacent cam pieces to be processed is between 120 and 180 mm, and the furnace is loaded after hoisting. The number of pieces loaded in each furnace should be ≤ 13. The actual picture after hoisting is as follows Figure 1 As shown;

[0084] S3, insulation stage: after loading the furnace, the furnace temperature is raised to 795°C, the carbon potential is controlled between 0.6 and 0.8%, and the insulation treatment is carried out for 50 minutes;

[0085] S4, quenching stage: stir the quenching oil for 3 minutes, then use the quenching oil with a starting temperature of 70°C to perform static oil quenching on the cam piece to be treated for 16 minutes, control the oil outlet temperature of the cam piece to be treated to be 100°C, and obtain the cam piece after heat treatment, such as Figure 2 shown.

[0086] Example 3

[0087] A heat treatment method for a 20CrNiMo cam sheet comprises the following steps:

[0088] S1, heating stage: the furnace temperature is raised to the quenching temperature of 805°C, and the carbon potential in the furnace is controlled in the range of 0.6-0.8%;

[0089] S2, loading stage: hoist the cam pieces to be processed, the spacing between adjacent cam pieces to be processed is between 120 and 180 mm, and the furnace is loaded after hoisting. The number of pieces loaded in each furnace should be ≤ 13. The actual picture after hoisting is as follows Figure 1 As shown;

[0090] S3, insulation stage: after loading the furnace, the furnace temperature is raised to 805°C, the carbon potential is controlled between 0.6% and 0.8%, and the insulation treatment is carried out for 50 minutes;

[0091] S4, quenching stage: stir the quenching oil for 3 minutes, then use the quenching oil with a starting temperature of 70°C to perform static oil quenching on the cam piece to be treated for 16 minutes, control the oil outlet temperature of the cam piece to be treated to be 100°C, and obtain the cam piece after heat treatment, such as Figure 2 shown.

[0092] Comparative Example 1

[0093] A conventional heat treatment method for a cam piece comprises the following steps:

[0094] S1, heating stage: the furnace temperature is raised to the quenching temperature of 820°C, and the carbon potential in the furnace is controlled in the range of 0.6-0.8%;

[0095] S2, loading stage: hoist the cam pieces to be processed, the spacing between adjacent cam pieces to be processed is ≥80mm, and the furnace is loaded after the hoisting is completed. The number of pieces loaded in each furnace should be ≤13. The actual picture after hoisting is as follows Figure 1 As shown;

[0096] S3, insulation stage: after loading the furnace, the furnace temperature is raised to 820°C, the carbon potential is controlled between 0.6% and 0.8%, and the insulation treatment is carried out for 70 minutes;

[0097] S4, quenching stage: the quenching oil is stirred for 3 minutes, and then the quenching oil with a starting temperature of 70° C. is used to stir and quench the cam piece to be treated for 16 minutes to obtain a cam piece after heat treatment.

[0098] The structural schematic diagram of the cam piece 1 obtained by the above heat treatment method is as follows: Figure 3 and Figure 4 As shown. Due to the bending deformation of the parts after quenching, these parts (such as Figure 3 The deformed part circled in the middle 2) has a size deviation and is along Figure 4 The middle shear head is deformed and black skin is present after grinding, which results in the cam piece 1 being unqualified.

[0099] Detection and analysis

[0100] The cam pieces obtained by heat treatment in Example 1, Example 2 and Example 3 were subjected to hardness test and deformation test.

[0101] The hardness test was conducted using a Rockwell hardness tester. The deformation test was conducted by placing the heat-treated cam piece horizontally and using a feeler gauge to test the deformation on both sides of the part. The test results are shown in Table 1.

[0102] Table 1 Cam plate hardness and deformation test results

[0103]

[0104] Each hardness value in Table 1 represents the average value obtained by testing the same part of all parts in this batch, and the three hardness values ​​represent three different parts of the parts. From the analysis of Table 1, it can be seen that, except for one unqualified part in Example 3, the deformation of the cam pieces obtained after heat treatment in other Examples 1 to 3 is less than or equal to 0.4 mm, and the hardness is between 58 and 62 HRC, which meets the process setting requirements.

[0105] In summary, a heat treatment method for a cam piece of the present invention firstly ensures the uniformity of heating and cooling of the parts during the quenching process by accurately controlling the loading method and quantity of the parts, thereby reducing deformation. Secondly, the quenching temperature and holding time of the parts are strictly controlled to reduce the proportional changes of each phase and reduce thermal stress and tissue stress. Thirdly, by shortening the holding time, the self-weight deformation of the parts during the holding stage can be effectively reduced. Fourthly, by changing the quenching method, the starting temperature of the quenching oil is set at 60-80°C, and the oil is stirred for 2-3 minutes before quenching to ensure that the quenching liquid temperature is uniform. Finally, the "static oil" quenching technology is used during the quenching process to minimize the deformation of the parts. The parts are cooled in the quenching oil for 15-20 minutes, and the oil outlet temperature is controlled at 80-110°C. Slowing down the cooling rate helps to reduce the quenching stress, thereby reducing the deformation after quenching. This method broadens the application range of the cam piece, especially in the field requiring high dimensional accuracy and high wear resistance, and has significant promotion and application value.

[0106] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or change made by a person skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A heat treatment method for a cam piece, characterized in that: The following steps are involved: Heating stage: the furnace temperature is raised to the quenching temperature, and the carbon potential control range in the furnace is the first preset value; Loading stage: hoist the cam pieces to be processed and load them into the furnace; Insulation stage: after loading the furnace, the furnace temperature is raised to the quenching temperature, the carbon potential control range is the first preset value, and the insulation treatment is performed for the first preset time; Quenching stage: using quenching oil with a starting temperature of a first preset temperature to perform static oil quenching on the cam piece to be processed for a second preset time, controlling the oil outlet temperature of the cam piece to be processed to be the second preset temperature, and obtaining a cam piece after heat treatment; The second preset temperature is greater than the first preset temperature.

2. The heat treatment method according to claim 1, characterized in that The quenching temperature is 790°C to 805°C.

3. The heat treatment method according to claim 1, characterized in that: The first preset value is 0.6~0.8%.

4. The heat treatment method according to claim 1, characterized in that: The time for loading the furnace is within 5 minutes; And / or, the hoisting method is vertical hoisting, and the hoisting interval between adjacent cam pieces to be processed is 120-180 mm.

5. The heat treatment method according to claim 1, characterized in that: The first preset time is 40 minutes to 60 minutes.

6. The heat treatment method according to claim 1, characterized in that: The first preset temperature is 60°C to 80°C; And / or, the quenching oil needs to be stirred for 2 to 3 minutes before quenching.

7. The heat treatment method according to claim 1, characterized in that: The second preset time is 15 to 20 minutes; And / or, the second preset temperature is 80°C~110°C.

8. The heat treatment method according to claim 1, characterized in that: The components of the cam plate include, by mass percentage, 0.17% to 0.23% carbon, 0.17% to 0.37% silicon, 0.60% to 0.95% manganese, ≤0.035% sulfur, ≤0.035% phosphorus, 0.40% to 0.70% chromium, 0.35% to 0.75% nickel, 0.20% to 0.30% molybdenum and ≤0.30 copper.

9. A cam piece, characterized in that: The product is obtained by the heat treatment method according to any one of claims 1 to 8.

10. The cam piece according to claim 9, characterized in that: The hardness of the cam piece is 58-61HRC, and the deformation of the cam piece is ≤0.4mm.

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