Accurate calculation method for quantitative heat treatment shape coefficient

Abstract

The invention belongs to the technical field of part manufacturing, and particularly relates to an accurate calculation method for a quantitative heat treatment shape coefficient. The method specifically comprises the following steps that 1, the thickness direction of a to-be-treated part is determined according to the structural form of the to-be-treated part; 2, the thickness size, determined in the step 1, of the to-be-processed part in the thickness direction serves as a unit, and the sizes of other dimensions of the to-be-processed part are converted into the proportion value of the thickness size; 3, according to the structural form and the thickness size of the to-be-treated part, the heating rate coefficient of the to-be-treated part is obtained through calculation; and 4, calculating the shape coefficient of the to-be-processed part by using the heating rate coefficient of the standard shape and the heating rate coefficient of the to-be-processed part calculated in the step 3. The method has the advantages that simple calculation is used, qualitative analysis of the part heat treatment shape coefficient determination method is converted into quantitative calculation, the size parameters of the part serve as variables, the corresponding relation is established through the expressions of the shape coefficient, the part surface area and the volume, and the part heat treatment shape coefficient determination method is obtained. The accurate numerical value of the heat treatment shape coefficient can be directly calculated according to the relational expression.

Description

Technical Field

[0001] The invention belongs to the technical field of parts manufacturing, and in particular relates to an accurate calculation method for a quantitative heat treatment shape coefficient. Background Art

[0002] Heat treatment refers to a metal heat processing process in which materials are heated, kept warm, and cooled in a solid state to achieve the desired organization and performance. The heat treatment process can be simplified into one or more heating-keeping-cooling processes, in which the control of temperature and time is the key factor. Condition thickness is a common method for calculating the heat treatment holding time of steel parts. Condition thickness is the actual thickness (wall thickness) multiplied by the shape coefficient. The shape coefficients of parts with different structural forms are different. The difference in shape coefficients will affect the size of the condition thickness, thereby affecting the selection of heat treatment holding time, and further affecting the heat treatment process.

[0003] However, the shape coefficients of the same part structure still vary greatly in different industries and even different editions of heat treatment standards. The shape coefficients set by the standards are repeatedly adjusted without significant basis. For example, in aviation and aerospace related standards, the shape coefficients of spheres and cubes are generally set to 0.75, but in some aerospace standards, they were set to 0.5-0.75. For example, the shape coefficient of plates is set to 1.5, 1.75 and 2 respectively according to the width-to-thickness ratio of the section in most standard documents, but in the 2011 edition of the standard "Heat Treatment of Stainless Steel for Aviation", it is uniformly set to 2 regardless of the width-to-thickness ratio. In the same standard, the shape coefficients of parts with complex surfaces are set to 1.5, 1.75 and 2 respectively according to the size ratio of the thickest part. The thickest part in the standard is obviously based on the plate. In addition to the repeated adjustment of the numerical settings without basis, the restrictions on part shapes in various standards are relatively broad, and the applicability to some parts is poor. Taking plates as an example, in most standards, when the plate width b is less than or equal to twice the plate thickness a (i.e. b≤2a), the shape factor is 1.5, but this range includes the possibility that the plate width is equal to the plate thickness (i.e. b=a). At this time, the actual structural form of the part is a square bar, and the shape factor should be 1, which conflicts with the shape factor of the square bar. Taking round bars as an example, the conditional thickness is set to 1 in each standard, but the aspect ratio of the round bar is not limited in the standard. When the length of the round bar is much smaller than the diameter, the bar is essentially a cake material, which is closer to a plate part from the perspective of heat treatment.

[0004] In order to accurately calculate the heat treatment holding time of steel parts and avoid excessive deviation of the heat treatment holding time due to inaccurate calculation of the shape coefficient and differences in conditional thickness calculation, a theoretical calculation method is needed to optimize the existing shape coefficient, calculate the shape coefficient according to the size and shape of the specific parts, avoid conflicts caused by different structures, and accurately control the heat treatment holding time of the parts. Summary of the invention

[0005] Purpose of the invention: The purpose of the invention is to provide a precise evaluation method for quantitative heat treatment shape coefficient. The method can be used to accurately calculate the shape coefficient of steel parts during heat treatment, and further accurately obtain the condition thickness and insulation time of the heat treatment process, so as to ensure the quality of the heat treatment product and avoid energy waste caused by excessive insulation.

[0006] Technical solution of the present invention: In order to achieve the above-mentioned invention objectives, the present invention adopts the following technical solution: a method for accurately calculating the shape coefficient of quantitative heat treatment, which takes the specific dimensional parameters of different parts as variables, establishes a corresponding relationship between the structural dimensional parameters and the shape coefficient, and in actual production, the precise value of the thickness of the heat treatment condition can be directly obtained according to the relationship.

[0007] According to a first aspect of the present invention, a method for accurately calculating a shape coefficient of a quantitative heat treatment is proposed, which specifically comprises the following steps: Step 1: determining the thickness direction of the part to be treated according to the structural form of the part to be treated; Step 2: taking the thickness dimension in the thickness direction of the part to be treated determined in the step 1 as a unit, converting other dimensions of the part to be treated into proportional values ​​of the thickness dimension; Step 3: calculating the heating rate coefficient of the part to be treated according to the structural form and thickness dimension of the part to be treated; Step 4: calculating the shape coefficient of the part to be treated using the heating rate coefficient of the standard shape and the heating rate coefficient of the part to be treated calculated in step 3.

[0008] In a possible embodiment, in step 1, the thickness direction of the plate is the shortest axis, the thickness direction of the sphere is the diameter, the thickness direction of the rod is the diameter, and the thickness direction of the cake is the cake thickness.

[0009] In a possible embodiment, in step 3, the heating rate coefficient of the part to be processed is calculated by the following formula:

[0010]

[0011] Where A is a fixed coefficient, which is related to the thermal conductivity and heat capacity of the material itself.

[0012] In a possible embodiment, when the structure of the part to be processed is a sphere with a diameter a,

[0013] In a possible embodiment, the part structure to be processed is a circle with a diameter a and a length b.

[0014]

[0015] In a possible embodiment, when the part structure to be processed is a cube with a side length of a,

[0016]

[0017] In a possible embodiment, the structure of the part to be processed is a pipe with openings at both ends, an outer diameter of 2R, a wall thickness of a, and a length of b.

[0018]

[0019] In a possible embodiment, in step 4, the heating rate of the standard shape is calculated according to the following formula:

[0020] Use a standard tensile test bar, the bar diameter is the thickness a, the length b = xa,

[0021] but Usually the aspect ratio x of the standard tensile test bar is ≥10.

[0022] Preferably, x=10, that is

[0023] In a possible embodiment, in step 4, the shape coefficient of the part to be processed is calculated according to the following formula:

[0024]

[0025] The advantages of the present invention are: the advantages of the present invention are that the method for determining the heat treatment shape coefficient of the part is transformed from qualitative analysis to quantitative calculation by using simple calculations, the size parameters of the part are used as variables, and the expressions of the shape coefficient, the surface area and the volume of the part are used to establish a corresponding relationship, and the precise value of the heat treatment shape coefficient can be directly calculated according to the relationship. The method can be used to refine the heat treatment control accuracy, accurately hold the temperature, and avoid unnecessary energy loss caused by excessively long heat treatment holding time of the part due to qualitative determination of the shape coefficient based on the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of the method of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of a sphere and a cube;

[0028] Figure 3 It is a schematic diagram of the structure of a cylinder (cake, stick);

[0029] Figure 4 It is a schematic diagram of a tube structure with two ends open;

[0030] Explanation of the numbers in the figure: 1 diameter of the sphere, 2 side length of the cube, 3 thickness of the cake, 4 diameter of the cake, 5 diameter of the rod, 6 length of the rod, 7 wall thickness of the tube, 8 length of the tube, 9 diameter of the tube. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific settings and methods proposed below, but covers any improvements, replacements and modifications of structures, methods, devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0033] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0034] like Figure 1 As shown, a method for accurately calculating the shape factor of a quantitative heat treatment comprises the following steps:

[0035] Step 1: Determine the thickness direction of the part according to the structural form of the part to be processed;

[0036] For example, the shortest axis is for the plate, the diameter is for the sphere, the diameter is for the rod, and the thickness is for the cake.

[0037] Step 2: Taking the thickness dimension of the part to be processed in the thickness direction determined in step 1 as a unit, convert other dimensions of the part to be processed into proportional values ​​of the thickness dimension;

[0038] If the part to be processed is a plate with a length, width and thickness of 150 mm, 60 mm and 20 mm respectively, according to step 1, the thickness dimension in the thickness direction is 20 mm, then 20 mm is taken as the unit a, and the length, width and thickness are expressed as 7.5a, 3a and a respectively.

[0039] Step 3: Calculate the heating rate coefficient of the part to be processed according to the structure and thickness of the part to be processed;

[0040] The rate at which a part is heated is proportional to its surface area and inversely proportional to its volume. The heating rate of the part to be processed can be expressed as: Where A is a fixed coefficient, which is related to the thermal conductivity and heat capacity of the material itself. The structural form of the parts is different (rectangle, sphere, cylinder, tube, etc.). The expressions are different.

[0041] A sphere with diameter a,

[0042] A round bar with diameter a and length b,

[0043] A cube with side length a,

[0044] The cross section is a square with side length a, and the length of the square rod is b.

[0045]

[0046] The outer diameter of the pipe with two ends open is 2R, the wall thickness is a, and the length is b.

[0047]

[0048] Step 4: Calculate the shape coefficient of the part to be processed by using the heating rate coefficient of the standard shape and the heating rate coefficient of the part to be processed calculated in step 3;

[0049] The greater the heating rate, the shorter the required heat treatment holding time and the smaller the shape coefficient. The ratio of the shape coefficient to the heating rate of two parts X and Y with different shapes can be expressed as:

[0050]

[0051] Since the heat treatment process test and the heat treatment holding time are determined by the tensile test bar test, the shape coefficient is determined based on the conventional tensile test bar as the standard, and its shape coefficient is set to 1. The shape coefficient of the part to be determined is calculated using the following formula:

[0052]

[0053] In the formula Using standard tensile test bar dimensions, the bar diameter is thickness a, length b = xa, then It can be expressed as Usually the standard tensile test bar aspect ratio x ≥ 10, when calculating the shape factor of the part to be determined, it is recommended that x = 10 for safety, that is, (According to the formula, the smaller x is, the larger the calculated shape coefficient is. Since the standard tensile test rod size is variable, it is recommended to follow the larger value when converting other structural shape coefficients. In this case, it is recommended to choose a smaller value for x).

[0054] Substitute the proportional values ​​of other dimensional parameters converted in step 2 with thickness as the unit into the above formula to calculate the shape coefficient of the part to be determined.

[0055] The following is an example:

[0056] Example 1

[0057] A sphere with diameter a is Figure 2 Shown as a sphere;

[0058] The thickness of the sphere is the diameter a of the sphere, and the structural parameter of the sphere is only the diameter length a. At this time, the standard shape factor is a round bar with an aspect ratio of 10. Calculate the shape coefficient of the sphere to be processed, which is

[0059] Example 2

[0060] A cube with side length a is Figure 2 As shown in the cube;

[0061] The thickness of the cube is the side length a, and the length, width and height of the cube are all converted to proportional values. At this time, the standard shape coefficient is calculated according to the rod with an aspect ratio of 20. Then the shape coefficient of the part to be processed is calculated as

[0062] Example 3

[0063] The round cake structure is Figure 3 As shown by the cylinder (pie);

[0064] The diameter of the round cake is 50mm and the length is 20mm. The thickness dimension is 20mm. Taking the thickness as the unit a, the ratio of the diameter dimension to the thickness dimension is b = 2.5a. At this time, the standard shape coefficient is based on a round bar with an aspect ratio of 10. Pending Calculate the shape coefficient of the part to be processed as

[0065] Example 4

[0066] Round rod structure Figure 3 The cylinder (rod) is shown;

[0067] The diameter of the round bar is 50mm, the length is 400mm, and the thickness dimension is 50mm. If the thickness is a, the length-to-thickness dimension ratio is b=8a. At this time, the standard shape coefficient is based on a round bar with an aspect ratio of 10. Pending Calculate the shape coefficient of the part to be processed as

[0068] Example 5

[0069] The structure of the open-ended tube is as follows: Figure 4 shown.

[0070] The pipe diameter is 60mm, the wall thickness is 5mm, the pipe length is 90mm, and the thickness dimension is set to 5mm. Taking the thickness dimension as the unit a, convert the pipe length and pipe diameter as the proportional value, then the pipe length b = 18a, and the pipe diameter 2R = 12a. At this time, the standard shape coefficient is based on a round bar with an aspect ratio of 30. Pending Calculate the shape coefficient of the part to be processed as

[0071] The above describes the specific embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also fall within the scope of protection of the present invention.

Claims

1. A method for accurately calculating the shape factor of a quantitative heat treatment, characterized in that: The specific steps include: Step 1: Determine the thickness direction of the part to be processed according to the structural form of the part to be processed; Step 2: Taking the thickness dimension of the part to be processed in the thickness direction determined in step 1 as a unit, convert the other dimensions of the part to be processed into a proportional value of the thickness dimension; Step 3: Calculate the heating rate coefficient of the part to be processed according to the structural form and thickness dimension of the part to be processed; Step 4: Calculate the shape coefficient of the part to be processed using the heating rate coefficient of the standard shape and the heating rate coefficient of the part to be processed calculated in step 3.

2. A method for accurately calculating a quantitative heat treatment shape coefficient according to claim 1, characterized in that: In step 1, the thickness direction of the plate is the shortest axis, the thickness direction of the sphere is the diameter, the thickness direction of the rod is the diameter, and the thickness direction of the cake is the cake thickness.

3. The method for accurately calculating the shape coefficient of quantitative heat treatment according to claim 1, characterized in that: In step 3, the heating rate coefficient of the part to be processed is calculated by the following formula: Among them, A is a fixed coefficient, which is determined by the thermal conductivity and heat capacity of the material itself.

4. A method for accurately calculating a quantitative heat treatment shape coefficient according to claim 3, characterized in that: When the structure of the part to be processed is a sphere with a diameter a, 5. The method for accurately calculating the shape coefficient of quantitative heat treatment according to claim 3, characterized in that: When the structure of the part to be processed is a round bar with a diameter of a and a length of b, 6. A method for accurately calculating a quantitative heat treatment shape coefficient according to claim 3, characterized in that: When the structure of the part to be processed is a cube with a side length of a, 7. The method for accurately calculating the shape coefficient of quantitative heat treatment according to claim 3, characterized in that: The structure of the part to be processed is a pipe with openings at both ends, an outer diameter of 2R, a wall thickness of a, and a length of b.

8. A method for accurately calculating a quantitative heat treatment shape coefficient according to any one of claims 3 to 7, characterized in that: In step 4, the heating rate of the standard shape is calculated according to the following formula: Use a standard tensile test bar, the bar diameter is the thickness a, the length b = xa, but Usually the standard tensile test bar aspect ratio x ≥ 10.

9. A method for accurately calculating a quantitative heat treatment shape coefficient according to any one of claims 3 to 7, characterized in that: In step 4, the shape coefficient of the part to be processed is calculated according to the following formula:

10. A non-transitory storage medium that non-transitory stores computer-executable instructions, wherein: When the computer executable instructions are executed by at least one processor, the computing method according to any one of claims 1 to 9 is implemented.

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