Processing method of small sealed cavity of corrosion-resistant soft magnetic alloy product

Abstract

This invention provides a machining fixture and method for small sealing cavities in corrosion-resistant soft magnetic alloy products. The method involves fabricating the machining fixture; selecting cutting tools based on the threaded holes of the product to be machined; rough machining the threaded holes using drilling and boring; rough machining the grooves; machining the threaded holes in layers; completing the finishing machining of the threaded holes and removing the first burrs; machining the sealing surface, leaving a margin on the sealing surface; and machining the sealing cavity (i.e., the sealing teeth) using a sealing tooth cutter at a speed of 2000 to 2200 r / min with a roughing feed rate of 0.02 to 0.0. 3mm / r, leaving a finishing allowance of 0.06 to 0.08mm; retract the tool quickly by 0.3 to 0.5mm midway, with a finishing feed rate of 0.01 to 0.02mm / r, and advance the tool to the theoretical depth of the sealing cavity; use a boring tool to move along the inner ring of the sealing teeth towards the minimum diameter Φ0.5 to Φ1, and use an inner grooving tool to move along the outer ring of the sealing teeth towards the groove diameter Φ5.3 to Φ6.3, to remove the final allowance and burrs on the sealing teeth, and use the boring tool and inner grooving tool to finish the threaded hole and groove dimensions.

Description

Technical Field

[0001] This invention relates to a machining tooling and machining method for small sealing cavities of corrosion-resistant soft magnetic alloy products, belonging to the fields of product machining and machine tool fixture technology. Background Technology

[0002] The bottom of a certain shell product is made of corrosion-resistant soft magnetic alloy Cr17NiTi, and its shape is mainly composed of a stepped circle of revolution and a small threaded inner cavity on the side. The main problems encountered during production are as follows:

[0003] 1. Too long alignment and processing time: Due to the irregular shape of this product, the clamping method for processing the side threaded holes is generally to use a combination fixture. However, the use of traditional combination fixtures has significant drawbacks. The clamping, alignment, and processing time for a single product is long, averaging 25 minutes per piece, which can no longer meet the needs of fast-paced mass production. New tooling is urgently needed to replace traditional tooling.

[0004] 2. Tool breakage during machining small sealing cavities: The threaded base hole of this product's sealing cavity is Φ4.5~Φ5.5, and the bottom face is a flat hole, which limits the tool diameter. Machining small tools places high demands on tool sharpening and machining path selection. Furthermore, the material of this product has good plasticity and toughness, but also high viscosity, making it prone to chip entanglement and tool breakage when machining small blind hole cavities. Tool reinstallation is necessary. Finish machining of Φ2.1~Φ4.1 small sealing teeth (60° end face annular groove) is shown in the attached image. Figure 4 When the surface roughness is too large at the ΦE dimension, the sealing teeth are prone to defects such as vibration marks, fish scale marks, and chipping.

[0005] 3. Manual application of coolant is time-consuming: The product is made of corrosion-resistant soft magnetic alloy Cr17NiTi, with an irregular shape. Traditional methods use a combination fixture for clamping, and the rotation speed cannot be set too high. When machining small sealing cavities, the surface roughness achieved using machine tool coolant is not ideal. Under low-speed conditions, only the traditional cooling method of carbon tetrachloride and lard can be used, requiring manual application of coolant to achieve the required surface roughness. This results in slow processing efficiency; therefore, while improving surface roughness, it is also necessary to shorten the processing time.

[0006] Currently, there are no similar high-quality solutions, either domestically or internationally. Summary of the Invention

[0007] The technical problem solved by this invention is to create a new tooling to replace traditional combination fixtures, thereby reducing the clamping, alignment, and processing time for individual products. The tooling dimensions are adapted to the product, and high speeds can be set during processing. The machine tool's self-spraying coolant replaces manual brushing of coolant, ensuring the surface roughness of the bottom end face of the sealing cavity.

[0008] The solution of this invention is: a method for processing a small sealing cavity in a corrosion-resistant soft magnetic alloy product, wherein the side of the soft magnetic alloy product is a threaded hole to be processed, the bottom of the threaded hole is a groove, the bottom of the groove is a sealing surface, and a sealing cavity is provided on the sealing surface, including:

[0009] Manufacturing and processing fixtures; the fixtures include a fixture body and a cover plate. One end of the fixture body is a clamping part, and the other end is provided with a mounting plane. A keyway is provided on the mounting plane. The keyway matches the lower end face of the product to be processed. The product is fitted onto the mounting plane using the nesting principle, and the surface to be processed is exposed on the side of the mounting plane. The upper end of the product is fixedly connected to the fixture body by the cover plate fastener.

[0010] Select the cutting tool according to the threaded hole of the product to be processed, and perform rough machining of the threaded hole by drilling and boring.

[0011] Rough-machined grooves;

[0012] The threaded hole is machined in layers to complete the finishing of the threaded hole and remove the first thread burr;

[0013] Machine the sealing surface, leaving a margin for it;

[0014] Machining of the sealing cavity, i.e., the sealing teeth, is carried out using a sealing tooth cutter (the depth is generally 0.3mm±0.05). The rotation speed is 2000 to 2200 r / min. The roughing feed rate is 0.02 to 0.03 mm / r, leaving a finishing allowance of 0.06 to 0.08 mm. First, the machining depth is 0.15±0.05, and then the tool is retracted by 0.3 to 0.5 mm using G0 code. The machining depth is then increased to 0.22 to 0.24 mm. The finishing feed rate is 0.01 to 0.02 mm / r, and the tool is fed to the theoretical depth of the sealing cavity.

[0015] Using a boring tool, cut along the inner ring of the sealing tooth towards the smallest diameter, and use an inner groove tool, cut along the outer ring of the sealing tooth towards the groove diameter, to remove the remaining material at the bottom end face of the final hole and the burrs on the sealing tooth;

[0016] Use boring tools and internal grooving tools to finish machine threaded holes and grooves.

[0017] Preferably, the tooling of the product is processed using a machining center to ensure that after the product is installed in the tooling, the total runout of the product's central axis relative to the tooling's central axis is within 0.01mm, while ensuring the accuracy of the keyway width value G±0.01mm, where G is the width of the protruding part of the end face of the product's threaded hole.

[0018] Preferably, the tooling axis of the processed product is used to detect and align the position of the first product, and subsequent batches of processed products do not require repeated alignment.

[0019] Preferably, during the roughing process of the groove, a layered feed method is adopted, with a pause between two feeds to remove chips using gas, and the depth of cut is ≤0.3mm.

[0020] Preferably, the threaded hole machining includes:

[0021] The first roughing process removes 0.3-0.4mm of excess material, and the depth of cut decreases from 0.2-0.15mm to 0.1-0.05mm with each pass.

[0022] The second layer of finishing removes the remaining material, with each cut depth of 0.05–0.03 mm.

[0023] After finishing the threads, a boring tool should be used to remove the burrs from the first thread.

[0024] Preferably, a 0.03-0.01mm allowance is left when machining the bottom end of the sealing surface with a boring tool.

[0025] Preferably, the selected internal grooving cutter, boring cutter, and sealing tooth cutter have a rake angle of 10° to 15°, a hardness value of HRC55 to 65, and are ground with an arc-shaped chip removal groove.

[0026] Preferably, the sealing tooth is a 60° end-face annular groove with a center diameter of Φ2.1~4.1mm, and the product material is Cr17NiTi. To prevent vibration marks from forming on the sealing tooth, a rotation speed of 2000 to 2200 r / min is selected, and the G04 program code pause is not allowed during finishing.

[0027] The advantages of this invention compared to the prior art are:

[0028] 1. Due to the use of self-made tooling, the rotation speed can be increased to 2000 to 3000 r / min. At the same time, when machining the bottom end face of the inner cavity seal, layered machining is selected and the machine tool's built-in cooling system is used, which solves the problem of excessive roughness of the bottom end face and avoids the time-consuming problem of manually brushing coolant.

[0029] 2. At the same time, after multiple tests, for Cr17NiTi material, when machining small diameter sealing teeth, leave a margin of 0.06 to 0.08 mm, and complete the finishing within one step (program segment) after tool adjustment (do not pause with program code G04, otherwise the sealing teeth will have surface defects), which solves the problem of excessive surface roughness of small sealing teeth with diameters of Φ2.1 to Φ4.1.

[0030] 3. The tooling of this invention has high reliability and accurate product positioning, enabling rapid loading and unloading. It significantly reduces product alignment time from 10 minutes to 2 minutes. After aligning the first product, it is not necessary to align every product during mass production. Compared with traditional combination fixtures, the maximum speed can be increased from 800 r / min to 3000 r / min, and the processing time per piece can be shortened from 25 minutes to 10 minutes, greatly improving production efficiency.

[0031] 4. It solves the problem of tool breakage, eliminating the need to replace tools and avoiding mid-process tool adjustments;

[0032] 5. This tooling is highly versatile, has a wide range of applications, and is easy to load and unload. It can be installed in most machine tool three-jaw chucks or cylindrical clamps.

[0033] 6. It generated economic benefits, reduced the cost of using combination fixtures, and saved on tooling costs. It saved approximately 2,000 yuan per 100 products.

[0034] In summary, by creating custom tooling, increasing the rotational speed, and improving the tool path, the machine tool's aqueous solution can directly replace the manual application of carbon tetrachloride and lard. This solves the problem of time-consuming manual operations, the problem of tool breakage during machining of small sealed cavities, improves production efficiency, and saves costs. Attached Figure Description

[0035] Figure 1 This is an assembly structure diagram, where 1 is the tooling body, 2 is the product, 3 is the cover plate, and 4 is the bolt;

[0036] Figure 2 Product image;

[0037] Figure 3 This is a drawing showing the main dimensions of the product.

[0038] Figure 4 This is a magnified view of a portion of the sealing cavity on the side of the product.

[0039] Figure 5 Tooling drawing;

[0040] Figure 6 To supplement the tooling 3D drawing;

[0041] Figure 7 Machining route diagram for sealing tooth (60° end face annular groove) ΦE;

[0042] Figure 8 This is a diagram of a sealing tooth cutting tool. Detailed Implementation

[0043] The present invention will be further described below with reference to the embodiments.

[0044] A method for machining a small sealing cavity in a corrosion-resistant soft magnetic alloy product, wherein the product is fitted onto the tooling body using a nesting principle while ensuring the product's positional accuracy requirements; the main machining methods include: tool selection and selection of the machining path for the sealing surface. The main machining steps are as follows:

[0045] Step 1: Rough machining of the inner hole, drilling and boring the inner hole of the product;

[0046] The parts that need to be processed in this invention are as follows: Figure 1-3 The product has a threaded hole on its side, with a groove at the bottom. The bottom surface of the groove is a sealing surface, and small sealing cavities, i.e., sealing teeth, need to be machined on the sealing surface. Figure 4 P is the distance between the axis of the threaded hole and the end face, which is the design value.

[0047] This invention requires tooling adapted to the product size. High-speed rotation can be set to improve product surface roughness and increase processing efficiency. The product is nested within the tooling using a contouring method, ensuring the inner thread cavity to be machined faces outwards, and the centerline of the product's inner cavity is coaxial with the outer circle centerline of the tooling (clamping area), effectively guaranteeing product position accuracy. The protruding parts of the product form a keyway / groove fit with the tooling, resulting in high precision. Simultaneously, the width Gmm (G width is 8-10mm) of the protruding end face of the product's threaded hole is held within the tooling groove, restricting the product's lateral displacement and reducing alignment time.

[0048] The tooling of the present invention includes a tooling body 1 and a cover plate 3, such as... Figure 5 , 6 As shown, one end of the tooling body is a clamping part, and the other end is provided with an installation plane. A keyway is provided on the installation plane. The keyway matches the lower end face of the product to be processed. The product 2 is fitted into the installation plane using the nesting principle, and the surface to be processed is exposed on the side of the installation plane. The upper end of the product is fixedly connected to the tooling body by a cover plate fastener (bolt 4).

[0049] The workpiece material of this invention is a corrosion-resistant soft magnetic alloy Cr17NiTi, which is characterized by good plasticity and easy tool sticking during cutting. Therefore, the cutting tool must be sharpened, with a rake angle of 10° to 15°, and a circular arc-shaped chip removal groove should be sharpened. The tool material should not be too hard, and a hardness value of HRC55 to 65 should be selected, and it should also have a certain degree of toughness. The grade S can be selected for tools that are suitable for nickel and titanium alloys. When selecting drilling tools, the drill bit and center drill should be made of high-speed steel material to avoid tool breakage during machining.

[0050] Step 2: Rough machining of the inner groove: Multiple feeds and frequent retractions should be used, with layered feeds. Pause midway using program code G04, blow away chips with low-pressure air, and keep the depth of cut ≤0.3mm to avoid chip entanglement and tool breakage;

[0051] Step 3: Machining M(F)×0.5 thread (F range is 5-6mm), S is the diameter of the outer step hole, designed value is 7-8mm: To avoid chip entanglement and tool breakage, it can be machined in two layers, and the chip blowing can be paused in the middle using G04;

[0052] 3.1 The first roughing layer removes 0.4mm of excess material, and the depth of cut decreases from 0.2mm to 0.1mm with each pass;

[0053] 3.2 The second layer of finishing removes 0.15mm of excess material, with a depth of cut of 0.05mm per pass;

[0054] 3.3 After finishing the thread, the first thread burr should be removed with a boring tool.

[0055] Step 4: Sealing surface processing, such as Figure 7 As shown:

[0056] 4.1 Use a small boring tool to machine the bottom surface of the sealing surface, leaving a 0.03mm allowance to avoid scratches and excessive roughness on the bottom surface;

[0057] 4.2 Calling as follows Figure 8 As shown, the sealing tooth (60° end face annular groove) is machined with a cutting tool at a speed of 2000 to 2200 r / min. According to the toolpath diagram, the roughing feed rate is 0.02 to 0.03 mm / r, leaving a finishing allowance of 0.06 to 0.08 mm. The tool is then rapidly retracted by 0.3 to 0.5 mm mid-machining, with a finishing feed rate of 0.01 to 0.02 mm / r, and the tool is driven to a depth of 0.3 mm (the specific depth depends on the product design dimensions). G04 pause is not used.

[0058] 4.3 After machining the sealing gauge, use a small boring tool and an internal grooving tool to cut to the diameter ΦE of the sealing tooth, within the range of Φ2.1 to Φ4.1, and then cut to the final depth. The small boring tool should cut along the inner ring of the sealing tooth towards the minimum diameter Φ0.5 to Φ1, while the internal grooving tool should cut along the outer ring of the sealing tooth towards the groove diameter Φ5.3 to Φ6.3. Remove the final allowance and burrs from the sealing tooth.

[0059] When machining small-diameter sealing teeth (60° end face annular groove) of Cr17NiTi material, leave a margin of 0.06 to 0.08 mm, and complete the finishing within one step (program segment) after tool adjustment (do not pause with program code G04, otherwise the sealing teeth will have surface defects). This can solve the problem of excessive surface roughness of small sealing teeth with diameters of Φ2.1 to 4.1 mm.

[0060] Because this invention uses self-made tooling, the rotation speed can be increased to 2000 to 3000 r / min. At the same time, when machining the bottom end face of the inner cavity seal, layered machining is selected, and the machine tool's built-in cooling system can solve the problem of excessive roughness of the bottom end face and improve machining efficiency.

[0061] Step 5: Finish machining of the inner hole and groove. Use a boring tool and an internal grooving tool to finish machining the inner hole and groove dimensions respectively.

[0062] Example

[0063] A method for processing a small sealing cavity in a corrosion-resistant soft magnetic alloy product, comprising the following steps:

[0064] 1. Make tooling.

[0065] Using a machining center, the product fixture is machined according to the tooling drawing, ensuring that the total runout of the machined part of the fixture relative to its own central axis is within 0.01mm, while ensuring the accuracy of the keyway width G ± 0.01mm, so that the product can be tightly nested within the fixture. The fixture has a threaded hole M(K)*1 machined on it to mate with bolt 4 (as shown in the attached image). Figure 1 The fastening bolts can secure the product. After processing, the position of the first piece needs to be checked. Once the first piece is aligned, subsequent pieces will not need to be aligned again.

[0066] 2. Select the cutting tool.

[0067] 2.1 The product's internal thread M(F) base hole is relatively small, therefore a cutting tool with a diameter of Φ4.5 should be selected.

[0068] 2.2 Because the product needs to be machined on the bottom face of the threaded hole (and the bottom face has a Φ1 small hole), the diameter of the boring tool passing through the bottom face is selected as Φ3.

[0069] 2.3 The workpiece material is a corrosion-resistant soft magnetic alloy Cr17NiTi, which has good plasticity and is prone to sticking to the tool during cutting. Therefore, the tool must be sharpened, with a rake angle of 15°, and a circular arc chip groove should be sharpened at the same time.

[0070] Note that the material of the cutting tool should not be too hard. A hardness value of HRC60 should be selected, and it should also have a certain degree of toughness. The grade should be S-class cutting tool.

[0071] 2.4 Examples of knife requisition are as follows:

[0072] ①The boring tool can be a Kyocera series Φ4.5 imported tool holder;

[0073] ② The internal grooving tool uses a Sandvik Φ4 tool holder with a main cutting edge width of 1.2mm;

[0074] ③ For the sealing tooth (60° end face annular groove), a Φ4 milling cutter bar can be used for sharpening. Note that the back angle should not be sharpened too much, otherwise it will easily break.

[0075] ④ For internal threading tools, black hardened tools are more suitable (reddish-brown hardened tools have too high hardness and are prone to breakage).

[0076] ⑤ The remaining roughing tools are sharpened using Φ4 alloy rods;

[0077] 2.5 Selection of drilling tools: Drill bits and center drills should be made of high-speed steel to avoid tool breakage during machining. A Φ5.2mm drill bit should be used for drilling.

[0078] 3. Process according to the processing flow.

[0079] The main processing steps are as follows:

[0080] Step 1: Rough machining of the inner hole, drilling and boring the inner hole of the product;

[0081] Step 2: Rough machining of the inner groove: Multiple feeds and frequent retractions should be used, with layered feeds. Pause midway using program code G04, blow away chips with low-pressure air, and use a depth of cut of 0.2mm to avoid chip entanglement and tool breakage;

[0082] Step 3: Machining M6×0.5 threads: To avoid chip entanglement and tool breakage, machining can be done in two layers, with G04 used to pause chip blowing in the middle;

[0083] 3.1 The first roughing layer removes 0.4mm of excess material, and the depth of cut decreases from 0.2mm to 0.1mm with each pass;

[0084] 3.2 The second layer of finishing removes 0.15mm of excess material, with a depth of cut of 0.05mm per pass;

[0085] 3.3 After finishing the thread, the first thread burr should be removed with a boring tool.

[0086] Step 4: Sealing surface processing:

[0087] 4.1 Use a small boring tool to machine the bottom surface of the sealing surface, leaving a 0.03mm allowance to avoid scratches and excessive roughness on the bottom surface;

[0088] 4.2 Machining route diagram for sealing tooth (60° end face annular groove) ΦE is as follows: Figure 7 As shown, the sealing toothed cutter is used to machine ΦE at a speed of 2200 r / min. According to the toolpath diagram, the roughing feed rate is 0.03 mm / r, leaving a finishing allowance of 0.08 mm. The tool is then quickly retracted by 0.3 mm midway through the machining process, with a finishing feed rate of 0.02 mm / r. The tool is then advanced to a final depth of 0.3 mm without using G04 to pause.

[0089] 4.3 After machining the sealing gauge, use a small boring tool and an internal grooving tool respectively, and cut to the diameter Φ4.1 of the sealing tooth, then cut to the final depth. The small boring tool cuts along the inner ring of the sealing tooth towards the minimum diameter Φ1, and the internal grooving tool cuts along the outer ring of the sealing tooth towards the groove diameter Φ6.3. Remove the final allowance and burrs from the sealing tooth.

[0090] Step 5: Finish machining of the inner hole and groove. Use a boring tool and an internal grooving tool to finish machining the inner hole and groove dimensions respectively.

[0091] The processing method described in this invention is also applicable to other products with similar shapes, and it is suitable for processing products made of soft magnetic alloy materials with different shapes but similar internal cavities.

[0092] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for processing a small sealing cavity in a corrosion-resistant soft magnetic alloy product, wherein the soft magnetic alloy product has a threaded hole to be processed on its side, a groove at the bottom of the threaded hole, a sealing surface at the bottom of the groove, and a sealing cavity is provided on the sealing surface, characterized in that... include: Manufacturing and processing fixtures; the fixtures include a fixture body and a cover plate. One end of the fixture body is a clamping part, and the other end is provided with a mounting plane. A keyway is provided on the mounting plane. The keyway matches the lower end face of the product to be processed. The product is fitted onto the mounting plane using the nesting principle, and the surface to be processed is exposed on the side of the mounting plane. The upper end of the product is fixedly connected to the fixture body by the cover plate fastener. Select the cutting tool according to the threaded hole of the product to be processed, and perform rough machining of the threaded hole by drilling and boring. Rough-machined grooves; The threaded hole is machined in layers to complete the finishing of the threaded hole and remove the first thread burr; Machine the sealing surface, leaving a margin for it; Machining of the sealing cavity (i.e., sealing teeth) is performed using a sealing tooth cutter at a speed of 2000 to 2200 r / min. The roughing feed rate is 0.02 to 0.03 mm / r, leaving a finishing allowance of 0.06 to 0.08 mm. The initial machining depth is 0.15 ± 0.05 mm, with the cutter retracting 0.3 to 0.5 mm, followed by machining to a depth of 0.22 to 0.24 mm. The finishing feed rate is 0.01 to 0.02 mm / r, with the cutter advancing to the theoretical depth of the sealing cavity. Using a boring tool, cut along the inner ring of the sealing tooth towards the smallest diameter, and use an inner groove tool, cut along the outer ring of the sealing tooth towards the groove diameter, to remove the remaining material at the bottom end face of the final hole and the burrs on the sealing tooth; Use boring tools and internal grooving tools to finish machine threaded holes and grooves.

2. The method according to claim 1, characterized in that: For rough machining, the machining depth is 0.15±0.05 mm, and the tool is retracted by 0.3 to 0.5 mm using the CNC G0 command; during finishing, the CNC G04 command is not allowed to be used to pause the process.

3. The method according to claim 1, characterized in that: The tooling of the product is processed using a machining center. After the product is installed in the tooling, the total runout of the product's central axis relative to the tooling's central axis is within 0.01mm. At the same time, the accuracy of the keyway width value is guaranteed to be G±0.01mm, where G is the width of the protruding part of the end face of the product's threaded hole.

4. The method according to claim 3, characterized in that: The tooling axis of the machined product is used to check and align the position of the first product. Subsequent batches of products will not require repeated alignment.

5. The method according to claim 1, characterized in that: During the roughing process of the groove, a layered feed method is adopted, with a pause between two feeds to remove chips with gas, and the depth of cut is ≤0.3mm.

6. The method according to claim 1, characterized in that: Threaded hole machining include: The first roughing process removes 0.3-0.4mm of excess material, and the depth of cut decreases from 0.2-0.15mm to 0.1-0.05mm with each pass. The second layer of finishing removes the remaining material, with each cut depth of 0.05–0.03 mm. After finishing the threads, a boring tool should be used to remove the burrs from the first thread.

7. The method according to claim 1, characterized in that: When machining the bottom end of the sealing surface with a boring tool, leave a margin of 0.03 to 0.01 mm.

8. The method according to claim 1, characterized in that: The selected internal grooving cutter, boring cutter, and sealing tooth cutter have a rake angle of 10° to 15°, a hardness value of HRC55 to 65, and are ground with an arc-shaped chip removal groove.

9. The method according to claim 1, characterized in that: The sealing tooth is a 60° end face annular groove with a center diameter of Φ2.1~4.1mm, and the product material is Cr17NiTi.

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