Machining method for narrow groove with large depth-to-width ratio

Abstract

According to the machining method for the large-depth-to-width-ratio narrow groove of the large clamping sleeve, a common three-axis numerical control mill is used, microscale feeding of a cutter is controlled through a basic numerical control program, after the milling cutter is instantly stressed, the milling cutter is immediately withdrawn and unloaded for buffering, and the radial continuous stress condition of the milling cutter is well improved; then arc interpolation is immediately carried out in a side milling mode, the narrow groove is widened according to needs for finish milling, the contact arc length of the cutter and the machining face can be reduced to the maximum extent, and friction force is reduced; and the circulating steps are repeatedly executed until the deep narrow groove is machined. In the machining process, radial stress of the cutter is small, continuous stress time is short, cutting edge abrasion is evenly distributed, the heat dissipation condition of the cutter is good, cutter breakage can be effectively avoided, and the service life of the cutter is prolonged. The machining depth of the milling cutter can reach about 7 times of the diameter-length ratio, the feeding frequency is greatly reduced, and the machining efficiency can be improved by 2-3 times.

Description

Technical Field

[0001] The present application relates to the technical field of numerical control machining, and in particular to a method for machining narrow grooves with a large aspect ratio. Background Art

[0002] In the field of mechanical manufacturing, milling of narrow slots with large depth-to-width ratio has always been a very challenging task. This type of slot is often found in the aerospace, shipbuilding and precision machinery industries, such as large jacket slits (see Appendix Figure 3 ), aircraft ear structure, motor rotor narrow slot and other parts processing, similar to this kind of deep narrow slot generally requires a small slot size, large depth and good surface quality. The performance of these parts is directly related to the stability and reliability of the entire system, so the processing accuracy and quality requirements are high.

[0003] Traditional milling processing methods, such as full-edge and full-slot milling, limited-time plunging and then expansion milling, high-speed and high-feed dynamic milling processing methods, and customized special disc milling cutters for deep and narrow groove processing, often face problems such as chipping, tool breakage, low efficiency, and poor surface quality when milling such narrow grooves with a large depth-to-width ratio. At the same time, the heat dissipation conditions in the processing area are also poor, which makes it easy for cutting heat to accumulate, the tool to wear quickly, and the tool life to be short. The tool cost is high and it is also easy to cause thermal damage to the workpiece, affecting the processing quality. It is difficult to achieve the precision requirements of narrow groove processing. Summary of the invention

[0004] In order to solve the above problems, an embodiment of the present invention provides a method for machining a narrow groove for a large jacket.

[0005] An embodiment of the present invention provides a method for machining a narrow groove with a large aspect ratio, the method comprising the following steps:

[0006] Step S1, using a drill bit to machine a cutter hole at the starting position of the groove to be machined, with a depth to the bottom of the groove;

[0007] Step S2, after replacing the milling cutter, cut down to the bottom of the processing groove at the pre-drilled hole;

[0008] Step S3, the milling cutter is fed along the narrow groove processing direction by T+0.05mm, where T is the slot gap width, calculated by the formula T=(slot width-milling cutter diameter)÷2, and the milling cutter is immediately withdrawn in the opposite direction by Tmm;

[0009] Step S4, circular interpolation is performed with the coordinate point after withdrawal as the center of the circle, and a semicircle with a radius of R=Tmm is side milled, and then the semicircle is returned to the center of the circle to reach the starting position of the next processing cycle, and the narrow groove is widened and finely milled to process the entire narrow groove to the required size, and also connected to the horizontal feed position of the previous step;

[0010] Step S5, repeating step S3 and step S4, when the narrow groove processing length reaches the specified processing length, stopping the processing, and completing the large aspect ratio narrow groove processing.

[0011] In some embodiments, the method further includes: selecting a drill bit and a milling cutter size that match the processing requirements, and determining the tool material and processing cutting parameters.

[0012] In some embodiments, determining the tool material includes: selecting a cemented carbide end mill for steel products.

[0013] In some embodiments, the selection of drill and milling cutter sizes that match the processing requirements includes: the diameter of the pre-drilled hole drill bit is selected to be equal to the width of the groove to be processed so as to facilitate cutting during milling.

[0014] In some embodiments, the selection of drill and milling cutter sizes that match the processing requirements also includes: the end mill diameter is selected to be 0.5 mm smaller than the processing groove size, and the milling cutter diameter is 0.5 mm smaller than the drill diameter.

[0015] In some embodiments, the step S1 further includes: if the starting position port of the processed groove is open, step S1 is omitted.

[0016] In some embodiments, step S2 further includes: the maximum processing depth of the milling cutter is the length of the entire cutting edge of the tool, achieving full-edge milling processing so that the wear of the tool edge is evenly distributed.

[0017] An embodiment of the present invention provides a high aspect ratio narrow groove machining tool, which is used to execute the high aspect ratio narrow groove machining method described in any of the above embodiments.

[0018] The method for processing narrow grooves with a large depth-to-width ratio of the present invention effectively solves the problems existing in traditional processing methods by unloading and buffering the milling cutter immediately after a slight lateral feed, and then combining it with a side processing method. Specifically, this method uses side milling to reduce the force on the tool, reduce the wear and breakage risk of the milling cutter, and increase the service life of the tool through unloading and buffering during processing; at the same time, by reducing the concentrated cutting heat, it can reduce tool vibration and thermal damage to the workpiece, and improve the quality of narrow groove processing. In addition, this method can also improve processing efficiency, shorten production cycles, and reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings illustrate generally, by way of example and not limitation, various embodiments discussed herein.

[0020] Figure 1 This is a schematic diagram of the processing details;

[0021] Figure 2 Schematic diagram of the processing steps;

[0022] Figure 3 It is a schematic diagram of the structure of the large jacket tank. DETAILED DESCRIPTION

[0023] In order to enable a more detailed understanding of the features and technical contents of the embodiments of the present application, the implementation of the embodiments of the present application is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present application.

[0024] In the embodiments of the present application, it should be noted that, unless otherwise specified and limited, the term "connection" should be understood in a broad sense. For example, it can be an electrical connection or a connection between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0025] It should be noted that the terms "first\second\third" involved in the embodiments of the present application are only used to distinguish similar objects, and do not represent a specific order for the objects. It is understandable that the specific order or sequence of "first\second\third" can be interchanged where permitted. It should be understood that the objects distinguished by "first\second\third" can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0026] Tool selection:

[0027] Taking ordinary three-axis CNC milling as an example, according to the part material and the length, width and depth of the groove to be processed, select the drill and milling cutter sizes that match the processing requirements, determine the tool material and processing cutting parameters; it is better to choose a carbide end mill for steel products; the diameter of the pre-drilled hole drill bit should be equal to the width of the groove to be processed, so that the cutter can be cut during milling; the end mill diameter is generally selected to be about 0.5mm smaller than the processing groove size, and the milling cutter diameter is 0.5mm smaller than the drill bit diameter

[0028] The embodiment of the present invention provides a method for machining a narrow groove with a large aspect ratio, such as Figure 2 As shown, the process includes the following steps S1 to S5.

[0029] Step S1, at the starting position of the groove to be processed, a hole is drilled with a drill bit to a depth of the groove bottom. This step can be omitted if the starting position of the groove to be processed is open.

[0030] Step S2, after changing the milling cutter, cut the pre-drilled hole to the bottom of the processing groove, see Figure 3 The maximum processing depth of the milling cutter can reach the entire cutting edge length of the tool, truly realizing full-edge milling processing, so the tool edge wear is evenly distributed.

[0031] Step S3, then the milling cutter feeds T+0.05mm along the narrow groove processing direction, and the center point of the tool trajectory is at point 1 at this moment, see the attached Figure 2 In step "1", the milling cutter immediately withdraws Tmm in the opposite direction to point 2, see the attached Figure 2 In step "2", the actual machining amount after the milling cutter completes these two steps is only a tiny amount of 0.05mm, see attached Figure 2 The dimension marked in step "1" means that the milling cutter retracts and unloads every 0.05mm of lateral feed, which can effectively avoid problems such as tool chipping and breakage caused by continuous increase in radial force on the tool.

[0032] T = (slot width - milling cutter diameter) ÷ 2 - also known as the slot gap width

[0033] Step S4, then use the coordinate point after the withdrawal as the center of the circle to perform circular interpolation, see the attached Figure 2 In step "3" of the side milling, a semicircle with a radius of R = Tmm is formed, and then the semicircle is returned to the center of the circle. Figure 2 Step "4" in the figure reaches the starting point of the next machining cycle. This step is mainly to widen and finish mill the narrow slot. The machining area is the arc interpolation area. See the attached Figure 2 In step "3", the entire narrow groove is machined to the required size and also connected to the horizontal feed position of the previous step;

[0034] Step S5, repeating steps S3-S4, when the narrow groove processing length reaches the specified processing length, stopping the processing, and completing the large aspect ratio narrow groove processing. This milling processing method can be figuratively called "pecking milling".

[0035] In the embodiment of the present invention, for instantaneous unloading after micro-feeding:

[0036] In the crosscutting process, a micro-feed strategy is adopted, that is, when the tool completes a given micro-feed, the feed is stopped and the tool is retracted immediately to unload the load to avoid the continuous increase of the radial force on the milling cutter. Figure 1 and Figure 2 , thereby effectively avoiding chipping, tool breakage and processing heat accumulation problems. Practice has proved that this milling method is very practical and effective.

[0037] In the embodiment of the present invention, for the side milling operation:

[0038] After unloading, the tool is used to expand and finish the narrow slot by using the side milling method. The side milling method can effectively reduce the contact area between the tool and the workpiece processing surface to reduce friction, reduce the generation of cutting heat and be more conducive to the diffusion of cutting heat.

[0039] Compared with the traditional cold processing scheme for narrow slots: In the traditional slot milling method, the contact arc length of the entire normal arc surface of the milling cutter reaches the maximum value, which is approximately 1 / 2 of the circumference of the tool. In this way, the friction force, radial cutting force, etc. all reach the maximum value, and the tool is constantly under force. In this way, during the processing, the axial processing depth of the tool will be greatly limited. If the depth of the narrow slot is slightly larger, it cannot be processed once, so it is necessary to increase the number of longitudinal passes, so the processing time will be longer, the processing efficiency will be low, and the vibration of the tool will also be aggravated, and the heat dissipation conditions will be worse, all of which will lead to poor processing quality of narrow slots.

[0040] After the milling cutter is slightly fed laterally, it immediately withdraws to unload and unload the force, and then performs arc interpolation side milling. This takes advantage of the fact that the tool is subjected to instantaneous force and is unloaded immediately without damaging the tool easily. At the same time, side milling reduces the radial cutting amount of the tool, greatly reduces the contact arc length between the tool and the workpiece, and reduces the friction force on the tool. During processing, the tool is subjected to a small comprehensive force, and can also unload and buffer, so a large axial cutting depth can be used to achieve full cutting edge of the milling cutter, and the cutting force is always controlled at a low level to avoid damage to the cutting tool; it can also ensure that the tool wear is evenly distributed, effectively improve the heat dissipation conditions, heat dissipation quickly, and extend the tool life.

[0041] An application example of the above embodiment of the present application is as follows. Assume that we want to process a jacket with a narrow groove with a large depth-to-width ratio, and the narrow groove size is 40mm in depth and 6.5mm in width. Tool selection:

[0042] Taking ordinary three-axis CNC milling as an example, according to the part material and the length, width and depth of the groove to be processed, select a Φ6.5mm ordinary high-speed steel drill bit that matches the processing requirements for pre-drilling the drop hole, select a Φ6mm extended end mill, and select a solid carbide milling cutter, which has better rigidity and higher processing surface quality;

[0043] At least the following steps are included:

[0044] Step S110, at the starting position of the groove to be processed, select the drill speed S800r / min, the feed speed F60mm / min, and use the drill to process a drop hole with a depth of ≥40mm. In this example, the starting position of the groove is open, so this step can be omitted.

[0045] Step S120, select the milling cutter cutting parameters as: rotation speed S1200r / min, feed speed F100mm / min, after changing the milling cutter, cut at the pre-drilled hole to a depth slightly larger than 40mm from the bottom of the groove.

[0046] Step S130, then feed T+0.05=0.3mm in the narrow groove processing direction, and immediately withdraw 0.25mm in the opposite direction of the feed. The actual processing amount of the milling cutter in this link is only 0.05mm each time.

[0047] T=(6.5-6)÷2=0.25————Also called the slit width

[0048] In step S140, circular interpolation is performed with the coordinate point of the milling cutter after withdrawal as the center of the circle in the previous step, and a semicircle with a radius of R=0.25mm is moved, and then the semicircle is returned to the center of the circle. In this way, the machined groove is widened and refined by side milling, and the entire narrow groove is machined to the required size and connected to the horizontal feed position of the previous step.

[0049] Step S150, repeating steps S130-S140, when the narrow groove processing length reaches the specified processing length, stopping the processing, and completing the large aspect ratio narrow groove processing. This milling processing method can be figuratively called "pecking milling".

[0050] The technical solutions described in the embodiments of the present application can be combined arbitrarily without conflict.

[0051] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for machining a narrow groove with a large aspect ratio, characterized in that: The method comprises the following steps: Step S1, using a drill bit to machine a cutter hole at the starting position of the groove to be machined, with a depth to the bottom of the groove; Step S2, after replacing the milling cutter, cut down to the bottom of the processing groove at the pre-drilled hole; Step S3, the milling cutter is fed along the narrow groove processing direction by T+0.05mm, where T is the slot gap width, calculated by the formula T=(slot width-milling cutter diameter)÷2, and the milling cutter is immediately withdrawn in the opposite direction by Tmm; Step S4, circular interpolation is performed with the coordinate point after withdrawal as the center of the circle, and a semicircle with a radius of R=Tmm is side milled, and then the semicircle is returned to the center of the circle to reach the starting position of the next processing cycle, and the narrow groove is widened and finely milled to process the entire narrow groove to the required size, and also connected to the horizontal feed position of the previous step; Step S5, repeating step S3 and step S4, when the narrow groove processing length reaches the specified processing length, stopping the processing, and completing the large aspect ratio narrow groove processing.

2. The method for machining a narrow groove with a large aspect ratio according to claim 1, characterized in that: The method also includes: selecting a drill bit and a milling cutter size that match the processing requirements, and determining the tool material and processing cutting parameters.

3. The method for machining a narrow groove with a large aspect ratio according to claim 2, characterized in that: The determination of tool materials includes: selecting carbide end mills for steel products.

4. The method for machining a narrow groove with a large aspect ratio according to claim 2, characterized in that: The method of selecting the drill and milling cutter sizes that match the processing requirements includes: selecting the diameter of the drill for pre-drilling the cutter hole to be equal to the width of the groove to be processed so as to facilitate cutting during milling.

5. The method for machining a narrow groove with a large aspect ratio according to claim 1, characterized in that: The selection of drill and milling cutter sizes that match the processing requirements also includes: the end mill diameter is selected to be 0.5 mm smaller than the processing groove size, and the milling cutter diameter is selected to be 0.5 mm smaller than the drill diameter.

6. The method for machining a narrow groove with a large aspect ratio according to claim 1, characterized in that: The step S1 also includes: if the starting position port of the processed groove is open, then step S1 is omitted.

7. The method for machining a narrow groove with a large aspect ratio according to claim 1, characterized in that: The step S2 also includes: the maximum processing depth of the milling cutter is the length of the entire cutting edge of the tool, achieving full-edge milling processing, so that the wear of the tool edge is evenly distributed.

8. A tool for machining narrow grooves with a large aspect ratio, characterized in that: Used to execute the method for machining narrow grooves with a large aspect ratio as described in any one of claims 1 to 7.

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