A small sealed ring groove numerical control milling method

Abstract

The application provides a small-sized sealing ring groove numerical control milling processing method, a common end face groove cutter is cooperated with an adjustable boring head, the cutter head is located at a center position of a ring groove to be processed when the cutter is set, a spiral cutter descending mode is adopted for cutting, and the cutter head rotates while spirally feeding along the ring groove processing position under the action of a main shaft of a machine tool. The method can realize the processing of sealing ring grooves of various specifications through one cutter and one clamping, is especially suitable for the processing of deep hole inner end face sealing ring grooves, is simple to operate, high in precision, and solves the problems of unadjustable customized cutter specification, prone to cutter joint marks in the processing process, long cutter customization period, and high cost and the like in the traditional method.

Description

Technical Field

[0001] This invention belongs to the field of machining and relates to a CNC milling method for small sealing ring grooves. Background Technology

[0002] The ignition device top cover is a key component of the engine. Each product has a different number of sealing ring grooves. Since the dimensional accuracy and appearance quality of the sealing grooves directly affect the overall sealing performance of the engine, the processing quality requirements are high.

[0003] Traditional machining methods use end mills with a diameter smaller than the width of the sealing ring groove. Since the sealing ring groove is located on the inner end face of a deep hole and its width is relatively narrow, only 1.5mm to 4mm, the machining space is narrow, making chip collection and removal difficult. In addition, the selected end mill shank is relatively thin, resulting in poor tool rigidity. During the cutting process, problems such as tool breakage, surface scratches, and dents are prone to occur, leading to dimensional deviations in the sealing ring groove.

[0004] Another approach is to use semi-customized, integral, dedicated cylindrical cutting tools for machining. This method allows for one-time machining of all dimensional features, resulting in high processing efficiency. However, to ensure the semi-customized, integral, dedicated cylindrical cutting tools meet strength requirements, YG6 cemented carbide is typically used. While this material has high hardness, the tool structure is irregular, requiring multiple machining processes (including special processes), leading to long customization cycles and non-adjustable machining dimensions. Therefore, the high cost, long production cycle, and non-adjustable dimensions of each tool restrict the production schedule of the ignition device top cover sealing ring groove process. Furthermore, the small cutting space between the workpiece and the tool makes chip removal and handling difficult, easily causing chip extrusion and tool breakage. This results in coarse tool marks and tool joint marks on the bottom surface of the sealing ring groove, leading to substandard surface quality. Additionally, the increasing variety of sealing ring groove specifications requires more diverse cutting tools, increasing the cost of customized tools and indirectly contributing to excessive production costs. Summary of the Invention

[0005] To address the problems of poor machining quality, low efficiency, and high cost in existing deep hole inner end face small sealing ring groove machining methods, this invention provides a CNC milling machining method for small sealing ring grooves.

[0006] The technical solution of this invention is: a CNC milling method for small sealing ring grooves, comprising the following steps:

[0007] Step 1: Select an adjustable boring head and a face grooving cutter according to the size of the small sealing ring groove to be processed; the width of the face grooving cutter should be greater than 1 / 2 the width of the sealing ring groove and less than the width of the sealing ring groove.

[0008] Step 2: Install the end face grooving cutter on the adjustable boring head, and install the workpiece on the milling machine for tool setting, so that the grooving cutter head is located at the center of the sealing ring groove to be machined;

[0009] Step 3: Set the processing parameters;

[0010] The tool speed shall not exceed 2000 rpm, and the tool shall rotate no less than 60 times within one revolution of the CNC milling machine spindle; the tool feed rate shall be determined based on the tool speed and the workpiece material.

[0011] The spiral feed method is adopted, and the spiral radius is calculated and determined according to the formula: spiral radius = (sealing ring groove width - cutting tool width) / 2;

[0012] The pitch is determined based on the workpiece material and machining accuracy;

[0013] Step 4: Start the CNC milling machine and machine the sealing ring groove;

[0014] Step 4.1: The cutter head is fed spirally along the annular groove machining position under the action of the machine tool spindle and rotates at the same time;

[0015] Step 4.2: Follow the spiral feed and cutting method in Step 4.1. When the tool reaches the bottom of the sealing ring groove, the tool will move around the circumference of the sealing ring groove to cut the bottom surface of the sealing groove.

[0016] Step 4.3: The cutter retracts along the spiral cutting path to the center of the sealing ring groove, and then retracts the cutter.

[0017] Furthermore, in step 3, the tool feed rate is 1.8 mm to 3 mm per minute.

[0018] Furthermore, the pitch ranges from 0.05 mm to 0.1 mm.

[0019] Furthermore, the width of the small sealing ring groove to be processed is 1.5mm to 4mm.

[0020] Furthermore, the small sealing ring groove to be processed is located on the end face of the deep hole inside the workpiece.

[0021] The beneficial effects of this invention are:

[0022] 1. The method of this invention uses a common end face grooving cutter and an adjustable boring head. The grooving cutter is installed on the adjustable boring head, and a spiral feed cutting method is adopted on a CNC milling machine. By setting a reasonable tool speed, the machining of the sealing ring groove on the end face of the deep hole is realized. The machining accuracy is high, which solves the problems of the sealing ring groove dimensional deviation caused by insufficient tool rigidity when using end mills, as well as the product surface damage and dents.

[0023] 2. The end face grooving cutter and adjustable boring head used in the processing method of this invention utilize the adjustable radial displacement of the cutter head. According to the specifications of the sealing ring groove to be processed, only the scale on the tool holder needs to be rotated, and the end face grooving cutter is adjusted to the center of the sealing ring groove through the adjustable boring head. This allows for the processing of deep hole end face sealing ring grooves of various specifications with one tool and one clamping, reducing costs and increasing efficiency. It solves the problems of traditional custom cylindrical cutters with non-adjustable specifications, easy tool marks during processing, and long tool customization cycle.

[0024] 3. The end face grooving tool used in the method of the present invention is a commonly used lathe tool. If the tool is severely worn, only the tool head needs to be replaced, which solves the problem of high production cost and long cycle of custom tools.

[0025] 4. The method of the present invention is applicable to the processing of sealing ring grooves, and is especially suitable for the processing of small sealing ring grooves on the inner end face of deep holes. Attached Figure Description

[0026] Figure 1 This is a flowchart of the processing method of the present invention;

[0027] Figure 2 This is a schematic diagram of the sealing ring groove to be processed;

[0028] Figure 3 This is a schematic diagram of the adjustable boring head used in this invention;

[0029] Figure 4 This is a schematic diagram of the end face grooving tool and the workpiece being aligned.

[0030] Figure 5 This is a schematic diagram of the tool path for the cutting tool to spiral down and the tool retraction path towards the center of the annular groove after machining.

[0031] Figure 6 This is a schematic diagram of the cutting edge cutting when the tool spirals to 0°.

[0032] Figure 7 This is a schematic diagram showing the cutting edge of the tool cutting when the tool spirals to 90°.

[0033] Figure 8 This is a schematic diagram showing the cutting edge of the tool cutting when the tool spirals to 180°.

[0034] Figure 9 This is a schematic diagram of the cutting edge cutting when the tool spirals to 270°.

[0035] Explanation of reference numerals in the attached diagram: d1—workpiece hole diameter, d2—outer diameter of sealing ring groove, d3—inner diameter of sealing ring groove, d4—outer cutting edge rotation diameter of the tool, d5—inner cutting edge rotation diameter of the tool, b1—offset between the center of tool rotation and the center of sealing groove, h1—sealing ring groove depth, h2—workpiece hole depth, h3—grooving tool width, h4—tool shank length, 1—machine tool spindle, 2—adjustable boring head, 3—end face grooving tool shank, 4—grooving tool head, 5—workpiece. Detailed Implementation

[0036] To improve the machining quality and efficiency of small sealing ring grooves on the inner end face of deep holes, this invention provides a CNC milling method for small sealing ring grooves, comprising the following steps:

[0037] Step 1: Select an adjustable boring head and end face grooving cutter according to the size of the sealing ring groove to be machined;

[0038] Define the workpiece hole diameter as d1, the outer diameter of the sealing ring groove as d2, the inner diameter of the sealing ring groove as d3, the groove depth of the sealing ring groove as h1, and the workpiece hole depth as h2; b1 is the offset between the tool rotation center and the sealing groove center, which is equal to the clearance value between the inner cutting edge of the tool and the inner circle of the sealing ring groove.

[0039] The length h4 of the end face grooving cutter is greater than the depth h2 of the workpiece hole, and the grooving width h3 of the end face grooving cutter is greater than 1 / 2 the width of the sealing ring groove and less than the width of the sealing ring groove.

[0040] Step 2: Mount the workpiece on the milling machine and set the tool.

[0041] The machine tool spindle drives the cutter head to move to the surface of the ring groove to be machined, so that the cutter head is located at the center of the ring groove. There are gaps between the inner and outer cutting edges of the cutter and the inner and outer circular surfaces of the sealing ring groove to be machined, respectively.

[0042] Step 3: Set the tool speed, feed mode, feed rate, tool path, and tool retraction path;

[0043] Because the tool itself is eccentric, excessively high tool speed will cause the tool to vibrate during the machining process. Therefore, the tool speed should be selected according to the tool speed reference table for different materials, and generally should not exceed 2000 rpm.

[0044] To ensure effective machining of the inner and outer surfaces of the sealing ring groove by the inner and outer cutting edges of the tool, the tool should rotate no less than 60 times during one helical rotation of the CNC milling machine spindle. That is, during one helical feed cycle, the tool should cut the inner and outer circles of the sealing groove no less than 60 times. Therefore, the feed rate needs to be determined based on the tool speed and workpiece material. The feed rate per revolution is 0.03mm-0.05mm, or the feed rate per minute is 1.8mm-3mm.

[0045] The machine tool spindle adopts a helical feed method, and the helical radius is equal to (the width of the sealing ring groove - the width of the cutting tool) / 2.

[0046] The pitch is determined based on the workpiece material and machining accuracy, and is generally 0.05-0.1mm.

[0047] Step 4: Start the milling machine and machine the sealing ring groove;

[0048] Step 4.1: The cutter head is fed spirally along the annular groove machining position under the action of the machine tool spindle and rotates at the same time;

[0049] Step 4.2: Perform helical feed machining as described in Step 4.1; when the tool reaches the bottom of the sealing ring groove, the tool moves around the circumference of the sealing ring groove to ensure that the bottom surface of the sealing groove is at the same height;

[0050] Step 4.3: After completing the machining of the sealing ring groove, the tool retracts to the center position of the sealing ring groove along the spiral cutting path, and then retracts in a straight line.

[0051] The method of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] See Figure 1 — Figure 9 The workpiece hole depth h2 = 60mm, the workpiece hole diameter d1 = 30mm, the outer diameter of the sealing ring groove to be processed d2 = 23mm, the inner diameter of the sealing ring groove d3 = 18mm, and the groove depth of the sealing ring groove h1 = 1.5mm.

[0053] The method for machining this small sealing ring groove includes the following steps:

[0054] Step 1: Select the end face grooving tool and adjustable boring head:

[0055] Based on the dimensions of the sealing ring groove to be machined, select the adjustable boring head 2 and the end face grooving cutter. Install the adjustable boring head on the machine tool spindle of the milling machine, and install the tool holder 3 of the end face grooving cutter on the adjustable boring head 2.

[0056] The length h4 of the end face grooving cutter is 62 mm, and the width h3 of the grooving cutter is 2 mm.

[0057] Step 2: Mount the workpiece on the CNC milling machine and perform tool setting.

[0058] Reference Figure 4 The milling machine spindle moves, driving the cutting tool to the plane where the sealing ring groove is located, and the cutting tool head is located at the center of the sealing ring groove to be processed. At this time, the gap between the outer and inner cutting edges of the cutting tool and the outer and inner circular surfaces of the sealing ring groove to be processed is 0.25mm, that is, the offset b1 between the center of tool rotation and the center of sealing groove is 0.25mm.

[0059] Step 3: Set the tool speed, feed rate, feed mode, tool path, and tool retraction path;

[0060] Reference Figure 4 According to the formula (seal ring groove width - cutter width) / 2, the helical radius in this embodiment is 0.25mm. The cutter uses a 0.25mm radius helical downward cut and helical retraction.

[0061] In this embodiment, the end face grooving tool is made of cemented carbide steel, the tool speed is selected as 1800 rpm, and the feed rate is 0.7 mm per minute.

[0062] The machine tool spindle uses a helical feed method. In this embodiment, the workpiece material is 30CrMnSiA, the machining accuracy is IT11 grade, and the pitch is selected as 0.05mm based on the workpiece material and machining accuracy.

[0063] Step 4: Start the milling machine and machine the sealing ring groove;

[0064] Step 4.1: The cutting tool makes a helical cut with a helical radius of 0.25 mm and a pitch of 0.05 mm. The cutting head is fed helically along the machining position of the annular groove under the action of the machine tool spindle and rotates on its own.

[0065] Step 4.2: Perform helical feed machining as described in Step 4.1. When the tool reaches the bottom of the sealing ring groove, the tool moves around the circumference of the sealing ring groove to ensure that the bottom surface of the sealing groove is at the same height.

[0066] Step 4.3: After the tool spirals back to the center of the sealing ring groove along the downward cutting path, it retracts in a straight line.

[0067] Reference Figures 6-9 This diagram illustrates the cutting action of the cutting tool when it spirals to the sealing ring groove at positions 0°, 90°, 180°, and 270°. At these four specific points, the outer edge of the cutting tool cuts the outer circle of the sealing ring groove, while the inner edge of the cutting tool cuts the inner circle of the sealing ring groove.

[0068] When the cutting tool and other parameters remain unchanged, only the helical radius is changed from 0.25mm to 0.5mm, a sealing ring groove with an inner diameter of 17.5mm and an outer diameter of 23.5mm can be machined, realizing the machining of annular sealing grooves of different specifications with one cutting tool.

[0069] This invention utilizes an adjustable boring head and a standard end-face grooving cutter on a CNC milling machine. The end-face grooving cutter is mounted on the adjustable boring head, and the cutter head is adjusted to position itself at the center of the ring groove to be machined. The machining offset is set via a CNC program, and a helical feed and helical cutting method is employed to achieve high-precision machining of the inner end face of a deep hole's sealing ring groove. When machining sealing ring grooves of different specifications, simply rotate the dial on the boring head's shank to adjust the cutter head to the center of the sealing ring groove, and reset the machining parameters. The operation is simple and reliable.

Claims

1. A method for CNC milling a small sealing ring groove, characterized in that, Includes the following steps: Step 1: Select an adjustable boring head and end face grooving cutter according to the size of the small sealing ring groove to be processed; The width of the end face groove is greater than 1 / 2 the width of the sealing ring groove and less than the width of the sealing ring groove; Step 2: Install the end face grooving cutter on the adjustable boring head, and install the workpiece on the milling machine for tool setting; adjust the adjustable boring head so that the cutter head of the end face grooving cutter is located at the radial center position of the sealing ring groove to be machined; and make the inner cutting edge and outer cutting edge of the end face grooving cutter have radial gaps with the inner and outer circular contours of the sealing ring groove to be machined, respectively. Step 3: Set the processing parameters; The tool speed shall not exceed 2000 rpm, and the helical movement of the CNC milling machine spindle and the tool shall meet the following requirements: during one helical rotation of the spindle, the tool shall rotate no less than 60 times; the tool feed rate shall be determined according to the tool speed and the workpiece material. When using a helical feed method, the helical radius is calculated and determined according to the following formula: Helical radius = (Sealing ring groove width - Groove cutter width) / 2; The pitch is determined based on the workpiece material and machining accuracy; Step 4: Start the CNC milling machine and machine the sealing ring groove; Step 4.1: Using the aforementioned helical radius and pitch, the cutter head is fed helically along the annular groove machining position under the action of the machine tool spindle while simultaneously rotating. Step 4.2: During the spiral feed process, the combined motion of the high-speed rotation of the tool and the spiral revolution of the spindle is used to make the inner and outer cutting edges of the end face grooving tool perform multiple continuous cuts on the inner and outer circular contours of the sealing ring groove within one revolution of the tool, so as to complete the forming of the sidewall of the ring groove. Step 4.3: When the tool reaches the bottom of the sealing ring groove, the tool moves around the circumference of the sealing ring groove to cut the bottom surface of the sealing groove. Step 4.4: The cutter retracts in the opposite direction along the spiral cutting path to the center of the sealing ring groove, and then retracts the cutter.

2. The CNC milling method for small sealing ring grooves as described in claim 1, characterized in that, In step 3, the tool feed rate is 1.8 mm to 3 mm per minute.

3. The CNC milling method for small sealing ring grooves as described in claim 1, characterized in that, The pitch ranges from 0.05 mm to 0.1 mm.

4. The CNC milling method for small sealing ring grooves as described in claim 1, characterized in that, The width of the small sealing ring groove to be processed is 1.5mm to 4mm.

5. The CNC milling method for small sealing ring grooves as described in claim 1, characterized in that, The small sealing ring groove to be processed is located on the end face of the deep hole inside the workpiece.

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