A method for intermittently processing threads of quenched materials

Abstract

This invention discloses a method for intermittent thread machining in hardened materials. During roughing, the tool's inclination angle is negative 8 to 12 degrees, and the machining process is performed in layers. The spindle speed is selected at a medium to low speed, and the cutting depth decreases layer by layer by C, based on the initial thread height E. Three cuts are made per layer, and roughing is completed when the thread height E-N*C equals 0. During finishing, the spindle speed is selected at a high speed, and the cutting depth decreases layer by layer by C, based on the initial thread height E. Two cuts are made per layer, and finishing is completed when the thread height E-N*C equals 0. Compared to thread machining by grinding, this method can improve efficiency by 3 to 5 times and reduce machining costs by 2 to 3 times.

Description

Technical Field

[0001] The invention relates to a technology for intermittently processing threads of high-strength materials, and in particular to a method for intermittently processing threads of quenched materials. Background Art

[0002] In CNC machining, threads are often produced on the outer diameter and inner bore of hardened materials (hardness HRC 55-62). Thread cutting is categorized into continuous and interrupted cutting. Continuous threading on the outer diameter and inner bore of workpieces with high hardness (HRC 55-62) is already challenging. The wind power industry, which has recently gained momentum, features large workpieces requiring intermittent threading on the outer diameter and inner bore of high-hardness (HRC 55-62). In practice, the large size of the workpieces creates significant impact, weakening the tool tip and causing it to easily chip, making normal cutting impossible. While thread grinding is typically the preferred process in the industry, it is inefficient and costly, with fragmented processing steps and high equipment investment, making it difficult to meet the high efficiency and low cost requirements. A more efficient and cost-effective alternative to thread grinding is currently needed. After extensive technical research, a turning-instead-of-grinding method has been developed. Summary of the Invention

[0003] The present invention designs a method for intermittent thread processing of quenched materials. Compared with thread processing by grinding, the processing method of the present invention can improve efficiency by 3 to 5 times and reduce processing costs by 2 to 3 times.

[0004] The technical solution disclosed in the present invention is as follows: A method for intermittently processing threads of quenched materials, comprising:

[0005] (1) Rough machining

[0006] (1) Tool selection;

[0007] (2) The tool edge inclination angle is negative -8 to -12 degrees.

[0008] (3) For layered processing, the spindle speed should be medium or low;

[0009] (3.1) The tool is positioned in the "X" direction to the outside of the workpiece outer diameter A, and in the "Z" direction to the outside of the right end face of the workpiece B. The distance between B and the right end face of the workpiece is at least greater than one pitch. Then, in the "X" direction, the tool is positioned away from the outer diameter - cutting depth C, and the thread processing program is started to process the first cut.

[0010] (3.2) The tool is retracted in the "X" direction to the workpiece outer diameter A, and positioned in the "Z" direction to the distance from the right end face of the workpiece to the distance from the outer diameter to the cutting depth C. The thread processing program is started to process the second cut;

[0011] (3.3) The tool is retracted in the "X" direction to the workpiece outer diameter A, and positioned in the "Z" direction to the distance from the right end face of the workpiece to the distance from the outer diameter to the cutting depth C. The thread machining program is started to process the third cut;

[0012] (3.4) The tool is retracted in the "X" direction to the outer diameter A of the workpiece, and positioned in the "Z" direction to the right end face B of the workpiece. The first layer of processing is completed.

[0013] Wherein, H=tanD*(EN*C), D is the tooth profile angle / 2, and E is the tooth profile height;

[0014] Repeat steps 3.1-3.4 to process the second to Nth layers. According to the initial tooth profile height E, the cutting depth decreases layer by layer by C, with 3 cuts per layer. When the tooth profile height EN*C=0, the roughing is completed.

[0015] (2) Finishing

[0016] (1) Tool selection, tool change and tool setting;

[0017] (2) During machining, select high spindle speed.

[0018] (2.1) The tool is quickly positioned in the "X" direction to the outside of the workpiece outer diameter F, and in the "Z" direction to the point Z = G + H + allowance from the right end face of the workpiece. The "X" direction is then positioned to the outer diameter, and the thread processing program is started, and the first cut is completed;

[0019] (2.2) Retract in the “x” direction to the outer diameter F of the workpiece, and in the “z” direction to the right end face of the workpiece where Z=GH-allowance, and then reposition in the “x” direction to the outer diameter. Start the machine tool processing button to execute the thread processing program, and the second cut is completed;

[0020] (2.3) The tool is withdrawn in the “x” direction to the outer diameter F of the workpiece, and in the “z” direction to the right end face of the workpiece at Z=G+H+allowance.

[0021] Repeat steps 2.1-2.3 to process the second to Nth layers. According to the initial tooth profile height E, the cutting depth decreases layer by layer by C, with 2 cuts per layer. When the tooth profile height EN*C=0, the finishing is completed.

[0022] Based on the above scheme, as a preferred method, in rough machining, the tool material is YG6X and the coating is WTIN.

[0023] On the basis of the above scheme, as a preferred embodiment, in finishing, the tool material is CBN and the coating is WTIN.

[0024] Based on the above solution, as a preferred embodiment, during rough machining, the spindle speed S = 30~50 rpm.

[0025] Based on the above solution, as a preferred embodiment, during finishing, the spindle speed S = 160~200 rpm.

[0026] Based on the above scheme, as a preferred embodiment, the outer diameter of the workpiece is 250mm, A is 260mm, B is 10mm, C is 0.5mm, D is 30 degrees, F is 260mm, G is 10mm,

[0027] Layered processing:

[0028] The tool is positioned in the "X" direction to the outer diameter of 260mm, and in the "Z" direction to 10mm away from the right end face of the workpiece. Then, in the "X" direction, it is positioned at 250-0.5=249.5mm away from the outer diameter. The cutting depth is started and the machine tool processing button is pressed to execute the thread processing program and process the first cut.

[0029] The tool is retracted in the "X" direction to the outer diameter of 260mm, and in the "Z" direction to 10+H-0.1mm away from the right end face of the workpiece. Then, it is retracted in the "X" direction to the outer diameter of 250-0.5=249.5mm, and the machine tool processing button is started to execute the thread processing program and process the second cut.

[0030] The tool is retracted in the "X" direction to the outer diameter of 260mm, and in the "Z" direction to 10-H+0.1mm from the right end face of the workpiece. Then, it is retracted in the "X" direction to the outer diameter of 250-0.5=249.5mm. The machine tool processing button is started to execute the thread processing program and process the third cut.

[0031] The tool is retracted in the "X" direction to an outer diameter of 260 mm, and in the "Z" direction to a position 10 mm away from the right end face of the workpiece. The first layer of processing is completed;

[0032] finishing:

[0033] The tool is quickly positioned to the outer diameter of 260mm in the "X" direction, and is positioned to the position Z=10+H+0.02 from the right end face of the workpiece in the "Z" direction. The "X" direction is then positioned to the outer diameter of 250mm. The machine tool processing button is activated to execute the thread processing program. The first cut is completed.

[0034] The "x" direction is withdrawn to the outer diameter of 260mm, and the "z" direction is withdrawn to the right end face of the workpiece at Z=10-H-0.02. The "x" direction is then positioned to the outer diameter of 250mm, and the machine tool processing button is started to execute the thread processing program. The second cut is completed.

[0035] The tool retreats to 260mm in the "x" direction and retreats to Z=10+H+0.02 on the right end face of the workpiece in the "Z" direction, and the first layer of processing is completed.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The rough machining tool is made of YG6X material with neutral toughness to make the tool impact-resistant, and the coating is WTIN to increase the hardness of the tool surface and make the tool wear-resistant during machining. The combined selection of the two greatly improves the tool life.

[0038] Because the workpiece is cut intermittently, the impact is significant. When using a tool with a negative rake angle, the tool tip is located at the lowest point of the main cutting edge. The tool first "cuts" into the workpiece from the rear of the stronger blade, then gradually "cuts" into the workpiece from the front. This protects the tool tip from direct impact, resulting in smooth turning and protecting the tool tip. It also redirects the cutting force, improving the blade's stress response, effectively extending tool life.

[0039] During rough machining, the spindle speed is selected to be low to increase the tool life.

[0040] The point-line processing method effectively decomposes the cutting force of rough processing and greatly improves the service life of the tool.

[0041] Compared with thread grinding, the processing method of the present invention can improve efficiency by 3 to 5 times and reduce processing costs by 2 to 3 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a structural diagram of the blade inclination angle;

[0043] Figure 2 It is a schematic diagram of layered processing;

[0044] Figure 3 This is a physical picture of one of the products processed by the present invention. DETAILED DESCRIPTION

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific embodiments of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings and other embodiments can be obtained based on these drawings without inventive work.

[0046] Taking the triangular external thread M250*3 as an example, the outer diameter of the workpiece is 250mm and the tooth angle is 60 degrees.

[0047] like Figure 1-3 As shown, 1. Rough machining

[0048] 1. Tool A selection, tool material: YG6X. Coating: WTIN.

[0049] Because the workpiece material is high hardness (HRC55-62) and intermittent machining creates high impact forces, which can easily chip the tool tip. Therefore, a tool body with neutral toughness is selected to enhance impact resistance. Furthermore, due to the high hardness of the product material, a WTIN coating is selected to increase the hardness of the tool surface, making it more wear-resistant during machining. This comprehensive selection significantly increases tool life.

[0050] 2. The tool edge inclination angle takes a negative value (-8~-12), such as Figure 1 shown

[0051] Because the workpiece is cut intermittently, the impact is significant. When using a tool with a negative rake angle, the tool tip is located at the lowest point of the main cutting edge. The tool first "cuts" into the workpiece from the rear of the stronger blade, then gradually "cuts" into the workpiece from the front. This protects the tool tip from direct impact, resulting in smooth turning and protecting the tool tip. It also redirects the cutting force, improving the blade's stress response, effectively extending tool life.

[0052] 3. Layered processing (taking triangular external thread M250*3 as an example), such as Figure 2 As shown,

[0053] (1) Due to the high hardness of the workpiece (HRC60-62) and intermittent processing, the spindle speed is selected to be low. For example: the outer diameter of the workpiece is 250mm, the spindle speed S=30-50. Improve the tool life.

[0054] (2) Position the tool in the "X" direction to 260mm of outer diameter, and in the "Z" direction to 10mm away from the right end face of the workpiece (Z=10), and then in the "X" direction to 250-0.5 (cutting depth) = 249.5mm away from the outer diameter, start the machine tool processing button to execute the thread processing program and process the first cut.

[0055] The tool is retracted in the "X" direction to 260mm of outer diameter, and positioned in the "Z" direction to 10+H-0.1mm (Z=10+H-0.1) away from the right end face of the workpiece, and then positioned in the "X" direction to 250-0.5=249.5mm away from the outer diameter. The machine tool processing button is started to execute the thread processing program and process the second cut.

[0056] The tool is retracted in the "X" direction to 260mm of outer diameter, and positioned in the "Z" direction to 10-H+0.1mm (Z=10-H+0.1) away from the right end face of the workpiece, and then positioned in the "X" direction to 250-0.5=249.5mm away from the outer diameter. The machine tool processing button is started to execute the thread processing program and process the third cut.

[0057] The tool is retracted in the "X" direction to an outer diameter of 260 mm and positioned in the "Z" direction to 10 mm away from the right end face of the workpiece (Z=10), and the first layer of processing is completed.

[0058] According to the variable of tooth profile height (cutting depth), the H value decreases by 0.5 mm (E-0.5*N) layer by layer, and the H value changes layer by layer according to the functional relationship H=tg30*(EN*C). The thread processing program code is used for processing layer by layer, with 3 cuts per layer. When the tooth profile height EN*C=0, the rough processing is completed.

[0059] The cutting depth 0.5 can be varied, ranging from 0.3 to 1.2 mm.

[0060] This processing method is a point-line processing method, which effectively decomposes the cutting force of rough processing and greatly improves the service life of the tool.

[0061] 2. Finishing

[0062] 1. B tool (tool changer), tool material: CBN (cubic boron nitride). Coating: WTIN.

[0063] Key points: (1) If the spindle speeds of tool A and tool B are the same, the tool tip zero points must be highly aligned when the two tools are aligned in the Z direction. (2) If the spindle speeds of tool A and tool B are different, the method for aligning tool B after tool A is aligned should be carried out according to my "Thread or Spiral Groove Repair Method", patent number: CN113419486B.

[0064] Because the spindle speed cannot be changed during thread processing, if the spindle speed changes, the threads will rot, so this is specially explained.

[0065] 2. Finishing

[0066] (1) Select the high speed spindle speed S=160~200 rpm.

[0067] (2) The tool is quickly positioned in the "X" direction to the outer diameter of 260 mm, and in the "Z" direction to the position Z=10+H+0.02 mm from the right end face of the workpiece. The "X" direction is then positioned to the outer diameter of 250 mm, and the machine tool processing button is activated to execute the thread processing program, and the first cut is completed.

[0068] The threading process is completed by retracting the machine in the "x" direction to an outer diameter of 260 mm and retracting it in the "z" direction to the right end face of the workpiece at Z = 10-H - 0.02 mm. The "x" direction is then repositioned to an outer diameter of 250 mm, and the machine tool processing button is activated to execute the threading process. The second cut is complete.

[0069] The tool is retracted to 260mm in the "x" direction and to the right end face of the workpiece at Z=10+H+0.02mm in the "z" direction. This completes the machining of one layer with two cuts.

[0070] The following variable (cutting depth) of the tooth profile height is reduced by 0.5 mm (EN*C) layer by layer. The H value changes layer by layer according to the functional relationship H=tg30*(EN*C). The thread processing program code is used to process each layer layer by layer, with 2 cuts per layer. When the tooth profile height is EN*C, the finishing is completed.

[0071] The cutting depth 0.5 can be varied, ranging from 0.3 to 1.2 mm.

[0072] The processing efficiency of this method for processing quenched intermittent threads is 3 to 5 times that of ground threads, and the processing cost is reduced by 2 to 3 times.

[0073] like Figure 3 Product example

[0074] In the process of processing intermittent threads of this product, the processing method of the present invention is used. When processing, the beat of each product is 95 seconds, and the tool tip life is 200 pieces / tip product; while when grinding threads, the beat of each product is 480 seconds, and the grinding wheel needs to be repaired 8 times to grind one product. In addition, the machine tool needs to be switched, which increases the process and auxiliary time. The cost of processing a single thread piece using the method of the present invention is 1.8 yuan, while the cost of grinding a single piece is 3.9 yuan.

[0075] In comparison, the processing method of the present invention can improve efficiency by 3 to 5 times and reduce processing costs by 2 to 3 times.

[0076] It should be noted that the above embodiments can be freely combined as needed. The above description is only a preferred embodiment of the present invention. It should be pointed out that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for intermittently processing threads of quenched materials, characterized in that: include, (1) Rough machining (1) Tool selection; (2) The tool edge inclination angle is negative -8 to -12 degrees. (3) For layered processing, the spindle speed is selected to be medium or low, the outer diameter of the workpiece is 250 mm, C is 0.5 mm, and D is 30 degrees; (3.1) Position the tool in the "X" direction to 260mm outside the outer diameter of the workpiece, and in the "Z" direction to 10mm outside the right end face of the workpiece, with a distance of at least one pitch from the right end face of the workpiece. Then, at 250-0.5=249.5mm in the "X" direction, start the thread machining program and process the first cut. (3.2) The tool is retracted in the "X" direction to 260mm of the workpiece outer diameter, and in the "Z" direction to Z = (10 + H - 0.1) mm from the right end face of the workpiece. Then, in the "X" direction, it is retracted to 250-0.5 = 249.5mm, and the threading program is started to process the second cut; (3.3) The tool is retracted in the "X" direction to 260mm of the workpiece outer diameter, and in the "Z" direction to Z = (10-H + 0.1) mm from the right end face of the workpiece. Then, in the "X" direction, it is retracted to 250-0.5 = 249.5mm, and the threading program is started to process the third cut; (3.4) The tool is retracted in the "X" direction to 260mm of the workpiece outer diameter, and in the "Z" direction to 10mm away from the right end face of the workpiece. The first layer of processing is completed. Wherein, H=tanD*(EN*C), D is the tooth profile angle / 2, and E is the tooth profile height; Repeat steps 3.1-3.4 to process the second to Nth layers. According to the initial tooth profile height E, the cutting depth decreases layer by layer by C, with 3 cuts per layer. When the tooth profile height EN*C=0, the roughing is completed. (2) Finishing (1) Tool selection, tool change and tool setting; (2) For processing, select high speed for the spindle speed. (2.1) The tool is quickly positioned in the "X" direction to 260 mm outside the outer diameter of the workpiece, and in the "Z" direction to Z = (10 + H + 0.02) mm from the right end face of the workpiece. The "X" direction is then positioned to 250 mm outside the outer diameter, and the thread processing program is started, and the first cut is completed; (2.2) Retract in the "X" direction to the workpiece outer diameter of 260mm, retract in the "Z" direction to the right end face of the workpiece Z = (10-H-0.02) mm, and then reposition in the "X" direction to the outer diameter of 250mm. Start the machine tool processing button to execute the thread processing program, and the second cut is completed; (2.3) The tool retreats in the "X" direction to the workpiece outer diameter of 260mm, and in the "Z" direction to the right end face of the workpiece Z = (10 + H + 0.02) mm, and the first layer of processing is completed. Wherein, H=tanD*(EN*C), D is the tooth profile angle / 2, and E is the tooth profile height; Repeat steps 2.1-2.3 to process the second to Nth layers. According to the initial tooth profile height E, the cutting depth decreases layer by layer by C, with 2 cuts per layer. When the tooth profile height EN*C=0, the finishing is completed.

2. The method for intermittently processing threads of quenched material according to claim 1, characterized in that: In rough machining, the tool material is YG6X and the coating is WTIN.

3. The method for intermittently processing threads of quenched material according to claim 1, characterized in that: In finishing, CBN is used as tool material and WTIN as coating.

4. The method for intermittently processing threads of quenched material according to claim 1, characterized in that: During rough machining, the spindle speed S=30~50 rpm.

5. The method for intermittently processing threads of quenched material according to claim 1, characterized in that: During finishing, the spindle speed S=160~200 rpm.

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