Silicon carbide crystal cutting liquid supply device and silicon carbide crystal cutting process

Abstract

The invention discloses a silicon carbide crystal cutting liquid supply device and a silicon carbide crystal cutting process, and relates to the technical field of silicon carbide machining.The silicon carbide crystal cutting liquid supply device comprises a liquid supply system, a control module and a first liquid supply pipeline used for spraying mortar to a cutting wire net; the second liquid supply pipeline is used for spraying mortar to the silicon carbide crystals; the nozzles B of the second liquid supply pipeline are positioned obliquely above the two sides of the cutting crystal; wherein the radius of the silicon carbide crystal is R, the transverse distance from the nozzle B of the second liquid supply pipeline to the cutting center is R + 20 mm to R + 200 mm, and the distance from the nozzle B of the second liquid supply pipeline to the vertical direction of the cutting center is R + 20 mm to R + 150 mm; and the first liquid supply pipeline and the second liquid supply pipeline are separately and independently controlled by the control module. The problems that in the existing silicon carbide crystal cutting process, the temperature control capability is insufficient, abrasive supply is insufficient, the cutting surface type quality is poor, and the productivity efficiency is low are solved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon carbide processing, and in particular to a silicon carbide crystal cutting liquid supply device and a silicon carbide crystal cutting process. Background Art

[0002] Silicon carbide substrate is one of the most commonly used base materials in semiconductor manufacturing, which has high purity and excellent electronic properties. In the process of preparing single-crystal silicon carbide substrate, the silicon carbide rod crystal needs to be cut and processed to obtain the desired particle or wafer shape.

[0003] Silicon carbide is difficult to cut due to its high hardness and brittleness. The most mature and mass-produced cutting method is the cutting method using diamond powder slurry and steel wire. During the cutting process of the slurry cutting equipment, there are only two liquid supply devices above the left and right groove wheels to spray slurry on the cutting steel wire. Therefore, the cooling and grinding of the crystal rod during the cutting process depends on the slurry brought by the fast-moving steel wire.

[0004] The inventors found that the existing cutting method has the following defects: during the cutting process, the temperature control ability and abrasive supply ability of the silicon carbide crystal rod are low, which will cause defects such as large thermal stress, large warping, and surface line marks on the cut substrate, while limiting the efficiency and capacity of silicon carbide crystal cutting. The above problems will be more prominent for the cutting of large-sized and long silicon carbide crystal rods, and the production efficiency will be lower. Summary of the invention

[0005] The embodiments of the present application provide a silicon carbide crystal cutting liquid supply device and a silicon carbide crystal cutting process, thereby solving the problems of insufficient temperature control capability and insufficient abrasive supply in the existing silicon carbide crystal cutting process, resulting in poor cutting surface quality and low production efficiency, while improving the cutting quality and production capacity of large-size and long-length silicon carbide crystals.

[0006] To solve the above technical problems, the present invention adopts the following technical scheme: a silicon carbide crystal cutting liquid supply device, comprising a liquid supply system, a control module, and a first liquid supply pipeline for spraying mortar onto a cutting wire mesh, and also comprising a second liquid supply pipeline for spraying mortar onto silicon carbide crystals; the nozzle B of the second liquid supply pipeline is located obliquely above both sides of the cutting crystal; the radius of the silicon carbide crystal is R, the lateral distance from the nozzle B of the second liquid supply pipeline to the cutting center is R+20mm~R+200mm, and the vertical distance from the nozzle B of the second liquid supply pipeline to the cutting center is R+20mm~R+150mm; the first liquid supply pipeline and the second liquid supply pipeline are independently controlled by the control module.

[0007] The device adds a second liquid supply pipeline, and the nozzle B of the second liquid supply pipeline can directly spray slurry on the crystal, which can more directly and efficiently take away the heat generated during the cutting process. At the same time, the second liquid supply pipeline sprays slurry on the crystal, which increases the supply path of abrasives. Compared with the traditional method of only relying on steel wire to carry materials, the second liquid supply pipeline can deliver more abrasives to the cutting area, making the cutting smoother, reducing the cutting resistance, and thus improving the grinding efficiency. Therefore, the liquid supply device can significantly improve the ability to control the temperature of the crystal rod during the cutting process, while increasing the grinding efficiency, thereby improving the surface quality of the silicon carbide substrate. In addition, the cutting length of this device is also greatly increased on the basis of ensuring the quality of the cutting surface. It is more beneficial to the cutting of large-size (6&8 inches) and long-length silicon carbide crystal rods, which can improve the cutting capacity efficiency, reduce costs, and ensure the surface quality of the substrate after cutting.

[0008] As a further improvement of the above scheme, the liquid supply system includes an online detection mechanism and a temperature measuring mechanism. Two online detection mechanisms are provided, one of which is connected to the first liquid supply pipeline, and the other is connected to the second liquid supply pipeline. Through the two online detection mechanisms, the mortar flow, density, temperature and other parameters of the first liquid supply pipeline and the second liquid supply pipeline can be monitored in real time respectively.

[0009] As a further improvement of the above scheme, the liquid supply system also includes a mortar liquid storage barrel, the mortar liquid storage barrel is connected to a mortar cooler, and the first liquid supply pipeline and the second liquid supply pipeline are respectively connected to the mortar cooler; the mortar temperature can be effectively reduced by the mortar cooler, thereby controlling the temperature during the cutting process and reducing the thermal stress of the silicon carbide crystals and mortar caused by high temperature.

[0010] As a further improvement of the above scheme, a temperature measuring mechanism is placed at the axial end and the outside of the circumference of the silicon carbide crystal; thereby, the temperature change can be measured quickly and accurately through the temperature measuring mechanism, and the temperature data can be transmitted to the control system in real time, so as to determine whether the temperature field of the crystal and mortar during the cutting process is within the allowable range.

[0011] As a further improvement of the above solution, the second liquid supply pipeline is connected to the feeding and swinging mechanism of the fixed crystal, and the angle adjustment range of the nozzle B in the second liquid supply pipeline is 0 to 30°; thereby ensuring that the nozzle B can be aligned with the crystal when the flow rate is adjusted.

[0012] The present invention also discloses a silicon carbide crystal cutting process, which uses the silicon carbide crystal cutting liquid supply device as described above and includes the following steps: a. Set cutting parameters and cutting fluid parameters; b. The first liquid supply pipeline supplies liquid to the cutting wire mesh, and the second liquid supply pipeline supplies liquid to the silicon carbide crystal; c. Monitor the crystal cutting process, including detecting the silicon carbide crystal and the temperature field data of the mortar in this area; d. Process the data to determine whether the temperature is within the allowable range of 20°C ± 5°C. If not, the control module adjusts the process parameters of the first liquid supply pipeline and the second liquid supply pipeline.

[0013] As a further improvement of the above scheme, the cutting parameters include: cutting line speed of 5 to 50 m / s, cutting line tension of 10 to 45 N, crystal feed speed of 0.1 to 5 mm / h, crystal swing angle range of 0 to 7°, and swing speed of 0 to 720 deg / min.

[0014] As a further improvement of the above scheme, the cutting fluid parameters include: the mortar flow rate of the first liquid supply pipeline is 1000~4000L / h, the mortar temperature is 10℃~25℃, and the density is 0.53kg / L; the mortar flow rate of the second liquid supply pipeline is 1000~3000L / h, the mortar temperature is 10℃~20℃, and the density is 0.53kg / L.

[0015] As a further improvement of the above scheme, under the condition that the cutting position has not reached the last 10mm range, when the temperature of the temperature field is detected to be too high, the mortar flow rate of the second liquid supply pipeline is increased and the mortar temperature is lowered first, and then the first liquid supply pipeline is adjusted and compensated, the mortar flow rate is increased, and the mortar temperature is lowered; then, one or several process parameter adjustments are made by reducing the workpiece feed speed, increasing the cutting line speed, increasing the cutting line tension and reducing the swing angle in this order until the temperature field returns to the set range.

[0016] As a further improvement of the above scheme, when the cutting position is within the last 10mm range, the mortar flow rate in the second liquid supply pipeline is adjusted to 1000L / h. If the temperature of the temperature field is detected to be too high during this time, the mortar temperature of the first liquid supply pipeline and the second liquid supply pipeline is preferentially reduced, and then one or several process parameters are adjusted in the order of reducing the workpiece feed speed and reducing the swing angular velocity until the temperature field returns to the set range.

[0017] It can be seen from the above technical solutions that the present invention has at least the following technical effects or advantages: This device adds a second liquid supply pipeline, and the nozzle B of the second liquid supply pipeline can directly spray mortar on the crystal, which can more directly and efficiently remove the heat generated during the cutting process. At the same time, the second liquid supply pipeline sprays mortar on the crystal, which increases the supply path of abrasives. Compared with the traditional method of relying solely on steel wire to carry materials, the second liquid supply pipeline can deliver more abrasives to the cutting area, making the cutting smoother, reducing cutting resistance, and thus improving grinding efficiency. Therefore, the ability to control the temperature of the crystal rod during the cutting process can be significantly improved through this liquid supply device, while increasing grinding efficiency, thereby improving the surface quality of the silicon carbide substrate.

[0018] In addition, the cutting length of this device is greatly increased while ensuring the quality of the cutting surface. It is more beneficial for cutting large-size (6 & 8 inches) and long silicon carbide crystal rods, which can improve cutting efficiency, reduce costs, and ensure the surface quality of the substrate after cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the description. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work: Figure 1 It is a schematic diagram of the structure of the liquid supply device for cutting silicon carbide crystals in the present invention; Figure 2 This is a flow chart of the liquid supply process for cutting silicon carbide crystals in the present invention; Figure 3 Comparison of cutting process parameters and cutting surface results in the present invention Figure 1 ; Figure 4 Comparison of cutting process parameters and cutting surface results in the present invention Figure 2 .

[0020] Explanation of the accompanying drawings: 1. First liquid supply pipeline, 2. Second liquid supply pipeline, 3. Online detection mechanism, 4. Mortar liquid storage barrel, 5. Agitator, 6. Mortar cooler, 7. Nozzle A, 8. Nozzle B. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments in this patent, other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this patent.

[0022] Embodiment 1 This embodiment discloses a liquid supply device for cutting silicon carbide crystals, which includes a liquid supply system, a control module, a first liquid supply pipeline 1 and a second liquid supply pipeline 2. The first liquid supply pipeline 1 and the second liquid supply pipeline 2 are both connected to the control module and can be controlled separately and independently. The first liquid supply pipeline 1 is used to spray mortar on the cutting wire net, and the second liquid supply pipeline 2 is used to spray mortar on the silicon carbide crystal.

[0023] The liquid supply system includes an online detection mechanism 3 and a temperature measurement mechanism. The online detection mechanism 3 is provided with two, such as Figure 1 As shown, two online detection mechanisms 3 are respectively connected to the first liquid supply pipeline 1 and the second liquid supply pipeline 2. The flow rate, density and other parameters of the mortar in the first liquid supply pipeline 1 and the second liquid supply pipeline 2 can be monitored in real time through the online detection mechanism 3. The relevant parameter information can be converted into a digital signal through an analog-to-digital conversion circuit. After the digital signal is processed and analyzed, it can be transmitted to the control module through a communication interface, thereby providing data support for the adjustment of subsequent process parameters. It should be understood that the control module and the online detection mechanism 3 can adopt existing technologies, which are well known to those skilled in the art, so they are not described in detail. The temperature measuring mechanism can be set in the axial and circumferential directions of the crystal (not shown in the figure). The temperature measuring mechanism can adopt a high-precision temperature sensor. The temperature measuring mechanism can quickly and accurately measure the temperature change, and transmit the temperature data to the control system in real time, so as to judge whether the temperature field of the crystal and mortar during the cutting process is within the allowable range.

[0024] In addition, the liquid supply system also includes a mortar liquid storage tank 4, which is equipped with a filter, a sedimentation tank, an agitator 5 and a circulation pump to ensure the quality and stability of the mortar. The mortar liquid storage tank 4 is connected to the first liquid supply pipeline 1 and the second liquid supply pipeline 2 through a mortar cooler 6, and the mortar cooler 6 can realize cooling control of the mortar.

[0025] Specifically in this embodiment, Figure 1 As shown, the nozzle A7 of the first liquid supply pipeline 1 is installed above the left and right wheel grooves and connected to the fixed platform to ensure the stability of its position. The circulating pump draws the mortar from the mortar storage barrel 4 and first sends it to the mortar cooler 6 to control the mortar temperature within the range of 10°C to 25°C. The cooled mortar then passes through the online detection mechanism 3 to measure and monitor the temperature and flow of the mortar, and finally flows to the nozzle A7 through the first liquid supply pipeline 1 to spray on the cutting wire mesh. The flow rate is maintained at 1000-4000L / h and the density is 0.5-3kg / L.

[0026] The second liquid supply pipeline 2 is connected to the feeding and swinging mechanism of the fixed crystal. The angle adjustment range of the nozzle B8 in the second liquid supply pipeline 2 is 0-30°, which can ensure that the nozzle B8 can be aligned with the crystal when the flow rate is adjusted. The circulating pump draws mortar from the mortar storage tank 4, and also passes through the cooling system to stabilize the mortar temperature at 10°C-20°C, then passes through the online detection mechanism 3, and finally flows to the corresponding nozzle B8 through the second liquid supply pipeline 2 and sprays on the cut crystal, wherein the mortar flow rate is 1000-3000L / h and the density is 0.5-3kg / L. In addition, the lateral distance from the nozzle B8 of the second liquid supply pipe to the center of the cut crystal is set to R+20mm-R+200mm, and the vertical distance is R+20mm-R+150mm (R is the radius of the silicon carbide crystal) to ensure the spraying effect.

[0027] Embodiment 2 This embodiment discloses a silicon carbide crystal cutting process, which uses the silicon carbide crystal cutting liquid supply device as described above. Figure 2 As shown, the specific steps are as follows: a. Set cutting parameters and cutting fluid parameters. Set appropriate cutting parameters and cutting fluid parameters according to cutting requirements. Cutting parameters include cutting line speed, cutting line tension, crystal feed speed, crystal swing angle and swing speed, etc. Cutting fluid parameters include mortar flow rate, mortar temperature and density of the first liquid supply pipeline 1 and the second liquid supply pipeline 2, etc.

[0028] In a specific embodiment of the present invention, the cutting parameters can be set as follows: the cutting line speed is 5 to 50 m / s, the cutting line tension is 10 to 45 N, the crystal feed speed is 0.1 to 5 mm / h, the crystal swing angle range is 0 to 7°, and the swing speed is 0 to 720 deg / min. The cutting liquid parameters can be set as follows: the mortar flow rate of the first liquid supply pipeline 1 is 1000 to 4000 L / h, the mortar temperature is 10°C to 25°C, and the density is 0.5 to 3 kg / L; the mortar flow rate of the second liquid supply pipeline 2 is 1000 to 3000 L / h, the mortar temperature is 10°C to 20°C, and the density is 0.5 to 3 kg / L.

[0029] b. The first liquid supply pipeline 1 supplies liquid to the cutting wire mesh, while the second liquid supply pipeline 2 supplies liquid to the silicon carbide crystal, and then cutting is performed. In this process, through the precise control of the control module, the flow rates in the first liquid supply pipeline 1 and the second liquid supply pipeline 2 can be independently adjusted to meet the needs of different cutting stages.

[0030] c. Real-time monitoring of the crystal cutting process, including detection of the temperature field data of the silicon carbide crystal and the mortar in this area.

[0031] d. Process the monitored data to determine whether the temperature is within the allowable range of 20℃±5℃. If the temperature exceeds the allowable range, the control module will adjust the process parameters of the first liquid supply pipeline 1 and the second liquid supply pipeline 2 according to the preset algorithm, such as mortar flow rate, mortar temperature, etc., to ensure the stability of the cutting process and the cutting quality.

[0032] Specifically in this implementation, under the condition that the cutting position has not reached the last 10mm range, when the temperature of the temperature field is detected to be too high, the mortar flow rate of the second liquid supply pipeline 2 is increased and the mortar temperature is reduced, and then the first liquid supply pipeline 1 is adjusted and compensated, the mortar flow rate is increased, and the mortar temperature is reduced; then, one or several process parameters are adjusted in the order of reducing the workpiece feed speed, increasing the cutting line speed, increasing the cutting line tension and reducing the swing angle until the temperature field returns to the set range.

[0033] When the cutting position is within the last 10mm range, adjust the mortar flow rate in the second liquid supply pipeline 2 to 1000L / h. If the temperature of the temperature field is detected to be too high during this time, give priority to reducing the mortar temperature of the first liquid supply pipeline 1 and the second liquid supply pipeline 2, and then adjust one or several process parameters in the order of reducing the workpiece feed speed and reducing the swing angular velocity until the temperature field returns to the set range.

[0034] In order to verify the effectiveness and reliability of the present invention, multiple cutting experiments were conducted. Figure 3 , Figure 4 shown.

[0035] Figure 3 and Figure 4 The results of cutting process parameters and cutting surface shape are shown in Figure 1. The temperature range detected by Scheme 1 is 33~49℃, and the cutting surface shape is poor. The reasons are analyzed as follows: first, the liquid supply system only sprays mortar on the wire mesh, the amount of steel wire material is limited, and the efficiency is low; second, the mortar flow rate is low and the mortar temperature is high, resulting in insufficient cooling capacity. Schemes 2 and 3 respectively verify that lowering the mortar temperature and increasing the mortar flow rate can improve the cooling capacity and improve the surface shape quality. Scheme 4 increases the cutting length of the silicon carbide crystal, generates more heat during cutting, and the detected temperature range is higher, resulting in a poor surface shape. This shows that the temperature field of cutting silicon carbide crystals affects the surface shape quality of the cutting substrate.

[0036] Scheme 5 uses the liquid supply device of the present invention, adds a second liquid supply pipeline 2, improves the cooling capacity and abrasive supply capacity, reduces the cutting temperature field temperature, and significantly improves the cutting surface quality. Schemes 6, 7, and 8 increase the crystal feed speed, increase the line speed, and increase the swing angle on the basis of Scheme 5 to increase the grinding efficiency. It is found that the detection temperature increases, resulting in poor surface quality. Schemes 9 and 10 use the liquid supply device of the present invention to increase the mortar flow rate and reduce the mortar temperature, providing sufficient cooling capacity and abrasive supply capacity for cutting large-size (6 & 8-inch) silicon carbide crystals, so that the cutting length of the silicon carbide crystal can be increased to 200 mm, while maintaining a lower temperature field temperature, so the cutting surface value is also smaller.

[0037] The experimental results show that the cutting surface quality can be significantly improved when the silicon carbide crystal cutting liquid supply device and cutting process provided by the present invention are used for cutting. At the same time, the cutting length of the device is greatly increased on the basis of ensuring the cutting surface quality. It is more beneficial for cutting large-size (6&8 inches) and long silicon carbide crystal rods, which can improve cutting efficiency, reduce costs, and ensure the surface quality of the substrate after cutting.

[0038] In the description of the present invention, the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "vertical", "horizontal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the purpose of describing the present invention rather than requiring the present invention to be constructed or operated in a specific position, and therefore should not be construed as limiting the present invention. The terms "connected" and "connected" in the present invention should be understood in a broad sense, for example, it can be a connection or a detachable connection; it can be a direct connection or an indirect connection through an intermediate component. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0039] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in their embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novelties disclosed herein.

Claims

1. A liquid supply device for cutting silicon carbide crystals, comprising a liquid supply system, a control module and a first liquid supply pipeline (1) for spraying mortar onto a cutting wire mesh, characterized in that: It also includes a second liquid supply pipeline (2) for spraying mortar onto the silicon carbide crystal; the nozzle B (8) of the second liquid supply pipeline (2) is located obliquely above both sides of the cut crystal; the radius of the silicon carbide crystal is R, the lateral distance from the nozzle B (8) of the second liquid supply pipeline (2) to the cutting center is R+20mm to R+200mm, and the vertical distance from the nozzle B (8) of the second liquid supply pipeline (2) to the cutting center is R+20mm to R+150mm; the first liquid supply pipeline (1) and the second liquid supply pipeline (2) are independently controlled by the control module.

2. A silicon carbide crystal cutting liquid supply device according to claim 1, characterized in that: The liquid supply system comprises an online detection mechanism (3) and a temperature measurement mechanism. Two online detection mechanisms (3) are provided, one of which is connected to the first liquid supply pipeline (1) and the other is connected to the second liquid supply pipeline (2).

3. A silicon carbide crystal cutting liquid supply device according to claim 2, characterized in that: The liquid supply system further comprises a mortar liquid storage barrel (4), the mortar liquid storage barrel (4) is connected to a mortar cooler (6), and the first liquid supply pipeline (1) and the second liquid supply pipeline (2) are respectively connected to the mortar cooler (6).

4. A silicon carbide crystal cutting liquid supply device according to claim 2, characterized in that: The temperature measuring mechanism is placed at the axial end and the outside of the circumference of the silicon carbide crystal.

5. The silicon carbide crystal cutting liquid supply device according to claim 1, characterized in that: The second liquid supply pipeline (2) is connected to the feeding and swinging mechanism of the fixed crystal, and the angle adjustment range of the nozzle B (8) in the second liquid supply pipeline (2) is 0 to 30 degrees.

6. A silicon carbide crystal cutting process, characterized in that: The silicon carbide crystal cutting liquid supply device according to any one of claims 1 to 5 comprises the following steps: a. Set cutting parameters and cutting fluid parameters; b. The first liquid supply pipeline (1) supplies liquid to the cutting wire mesh, while the second liquid supply pipeline (2) supplies liquid to the silicon carbide crystal; c. Monitor the crystal cutting process, including detecting the silicon carbide crystal and the temperature field data of the mortar in this area; d. Process the data to determine whether the temperature is within the allowable range of 20°C ± 5°C. If not, the control module adjusts the process parameters of the first liquid supply pipeline (1) and the second liquid supply pipeline (2).

7. A silicon carbide crystal cutting process according to claim 6, characterized in that: The cutting parameters include: cutting line speed of 5 to 50 m / s, cutting line tension of 10 to 45 N, crystal feed speed of 0.1 to 5 mm / h, crystal swing angle range of 0 to 7°, and swing speed of 0 to 720 deg / min.

8. A silicon carbide crystal cutting process according to claim 6, characterized in that: The cutting fluid parameters include: the mortar flow rate of the first liquid supply pipeline (1) is 1000-4000 L / h, the mortar temperature is 10°C-25°C, and the density is 0.53 kg / L; the mortar flow rate of the second liquid supply pipeline (2) is 1000-3000 L / h, the mortar temperature is 10°C-20°C, and the density is 0.53 kg / L.

9. A silicon carbide crystal cutting process according to claim 6, characterized in that: Under the condition that the cutting position has not reached the last 10 mm range, when it is detected that the temperature of the temperature field is too high, the mortar flow rate of the second liquid supply pipeline (2) is increased and the mortar temperature is reduced, and then the first liquid supply pipeline (1) is adjusted and compensated, the mortar flow rate is increased, and the mortar temperature is reduced; then, one or more process parameters are adjusted in the order of reducing the workpiece feed speed, increasing the cutting line speed, increasing the cutting line tension and reducing the swing angle until the temperature field is restored to the set range.

10. A silicon carbide crystal cutting process according to claim 6, characterized in that: When the cutting position is within the last 10 mm, the mortar flow rate in the second liquid supply pipeline is adjusted to be reduced to 1000 L / h. If the temperature of the temperature field is detected to be too high during this time, the mortar temperature of the first liquid supply pipeline (1) and the second liquid supply pipeline (2) is preferentially reduced, and then one or more process parameters are adjusted by reducing the workpiece feed speed and the swing angular velocity in sequence until the temperature field is restored to the set range.

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