High-straightness multi-stage laser micro-hole guided deep hole machining technology through hole expanding method

Abstract

The invention discloses a high-straightness multi-stage laser micro-hole guided reaming method deep hole machining process, which relates to the technical field of machining and comprises the following steps: S1, calibrating laser deep hole machining equipment; s2, calibrating workpiece clamping and repeated positioning based on a three-line aiming positioning method; s3, the small-diameter deep hole is machined through multi-stage laser; s4, the hole with the high depth-diameter ratio is expanded for one time or multiple times through laser small hole guiding, and finally the large-diameter deep hole with the needed precision is machined; small holes with high straightness are gradually formed through a multi-time laser deep hole machining technology, then one-time or multi-time hole reaming operation is carried out through a traditional deep hole machining method, and through the technology combining laser machining and the traditional hole reaming technology, deep holes with high straightness, roundness and cylindricity can be finally obtained. According to the method, the machining precision of the product can be remarkably improved, and the method has an extremely important positive influence on the improvement of the yield of the deep hole product and the economic benefits of enterprises.

Description

Technical Field

[0001] The present invention relates to the technical field of machining, and particularly to a deep hole machining process by an under-reaming method with high straightness and multi-stage laser micro-hole guiding. Background Art

[0002] According to statistics, in the machinery manufacturing industry, the processing of holes accounts for about 1 / 3 of all machining, and the processing of deep holes accounts for more than 40% of various hole machining. The definitions of small holes, micro-holes, and micro-deep holes are generally as follows: the aperture of a small hole is φ0.1mm - φ3.0mm; the aperture of a micro-hole is < φ0.1mm; generally speaking, a deep hole is defined as a hole with a hole depth to aperture ratio (depth-diameter ratio) > 5. Usually, the machining of micro-deep holes and extra-large deep holes is more difficult than that of medium and small diameter deep holes. The difficulty lies in that it is difficult to ensure the straightness error of deep holes.

[0003] There are various cutting motions for deep hole machining: the workpiece rotates and the tool feeds; the workpiece does not move, the tool rotates and feeds; the workpiece and the tool rotate relatively, and the tool feeds; the workpiece rotates and feeds, and the tool does not move. Generally speaking, there are mainly three motion forms: (1) the tool rotates; (2) the workpiece rotates; (3) the tool and the workpiece rotate in opposite directions simultaneously. During the machining process, the drill bit will be affected by different external factors in all three machining methods, resulting in the deflection of the drill bit, thereby affecting the straightness error of the machining accuracy (as Figure 6 shown). Among them, when the workpiece does not move and the tool rotates and feeds to machine a deep hole, the straightness is poor, and there will be a large deviation between the actual axis and the ideal axis of the machined workpiece. Moreover, the deep hole machining tool is in a semi-closed or closed state, so only experience can be relied on to judge whether the cutting process is normal. In the case of insufficient stiffness of the drill pipe, due to factors such as its own weight, vibration, and drilling force, the drill pipe may bend, thereby seriously affecting the machining quality of the hole. For the deep hole machining with the workpiece not moving and the tool rotating, how to ensure high straightness is an international problem. Especially for drilling with medium and large depth-diameter ratios, the drilling accuracy will be greatly reduced, resulting in out-of-tolerance and scrapping of products. Therefore, a deep hole machining process by an under-reaming method with high straightness and multi-stage laser micro-hole guiding is needed to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a deep hole machining process by an under-reaming method with high straightness and multi-stage laser micro-hole guiding to solve the problems existing in the prior art as mentioned in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A deep hole machining process by an under-reaming method with high straightness and multi-stage laser micro-hole guiding, comprising the following steps:

[0007] S1: Calibrate the laser deep hole machining equipment;

[0008] S2: Calibrate the workpiece clamping and repeat positioning based on the three-line aiming and positioning method;

[0009] S3: Machine small-diameter deep holes using multi-stage lasers;

[0010] S4: Use laser small hole guiding to enlarge the high-depth-to-diameter ratio hole one or more times to finally machine a large-diameter deep hole with the required accuracy.

[0011] Preferably, the specific steps for calibrating the laser deep hole machining equipment in S1 are as follows:

[0012] S11: Vertically arrange the processing laser, the upper laser sight, and the lower laser sight on the same straight line of the bracket. The distance between the upper laser sight and the lower laser sight is l1, and the distance between the lower laser sight and the processing laser is l2;

[0013] S12: Set the upper aiming point, the lower aiming point, and the preset hole position on the target board and on the same straight line. The distance between the upper aiming point and the lower aiming point is l1, and the distance between the lower aiming point and the preset hole position is l2;

[0014] S13: Arrange the laser bracket parallel to the target board with a spacing of l, where l is greater than the deep hole length of the workpiece to be machined. Make the upper laser sight and the lower laser sight on the laser bracket aim at the upper aiming point and the lower aiming point on the target board respectively, and then fix the upper laser sight and the lower laser sight;

[0015] S14: Adjust the calibration function of the processing laser to align it with the preset hole position, and fix the processing laser on the laser bracket. This is the initial position of the processing laser, and the calibration is completed.

[0016] Preferably, the specific steps of S2 are as follows:

[0017] S21: Align the preset hole position on the target board with the first preset hole position at one end of the workpiece, and fix the target board and the workpiece perpendicular to the corresponding axes of the first preset hole position and the second preset hole position on the workpiece;

[0018] S22: Adjust the laser bracket so that the upper laser sight and the lower laser sight on the laser bracket aim at the upper aiming point and the lower aiming point on the target board respectively. Start the calibration function of the processing laser to align it with the second preset hole position at the other end of the workpiece, and then fix the laser bracket, the workpiece, and the target board. The clamping is completed;

[0019] S23: During the processing, the target plate and the workpiece are relatively fixed. When laser focusing may cause the deviation of the processing line, to ensure the straightness of the processing, by adjusting the laser bracket, the upper laser sight and the lower laser sight are realigned with the upper aiming point and the lower aiming point on the target plate, and the processing laser is naturally aligned with the workpiece preset hole one and the workpiece preset hole two on the workpiece.

[0020] Preferably, the specific steps in S3 are as follows:

[0021] S31: Install a vacuum chamber between the processing laser and the workpiece. The vacuum chamber is assembled with the workpiece through a gasket to form a closed space, and a vacuum extraction outlet is provided on the vacuum chamber;

[0022] S32: Adjust the focus of the processing laser so that it falls on the workpiece preset hole two;

[0023] S33: Start the processing laser to drill holes. The laser ablation products generate air plasma. Due to the negative pressure of the vacuum chamber, the air plasma is discharged from the vacuum extraction outlet, forming a small hole with a certain depth;

[0024] S34: Measure the depth of the bottom of the small hole, and adjust the laser focus of the processing laser so that it falls near the bottom of the just-drilled small hole;

[0025] S35: Repeat step S33 to form a deeper two-stage small hole;

[0026] S36: Repeat steps S33, S34 and S35 repeatedly to form a through small hole or a blind hole with a certain depth.

[0027] Preferably, the specific steps in S4 are as follows:

[0028] S41: Install the workpiece with the small hole processed by laser on the middle hole drilling machine;

[0029] S42: Use a gun drill to expand the middle hole. The drill bit has a cutting edge with a taper of 120° - 150° at the top, and the taper of the cutting edge ensures that the drill bit cuts along the direction of the small hole;

[0030] S43: On the basis of guiding the expansion of the small hole to obtain the middle hole, use the middle hole as the guiding hole, and use a deep hole gun drill, BTA drill, ejector drill and DF deep hole drill to expand the hole again, and finally process a large-diameter deep hole with the required accuracy.

[0031] Preferably, in S36, the diameter d0 of the small hole is approximately 2 mm.

[0032] Preferably, in S42, the diameter d1 of the middle hole satisfies d1 ≤ 3d0, and in S43, the diameter d2 of the re-expanded hole satisfies d2 ≤ 3d1.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] Through multiple laser deep hole machining techniques, the present invention gradually forms small holes with high straightness. Subsequently, traditional and widely used deep hole machining methods are adopted for one or more reaming operations. Through this process that combines laser machining and traditional reaming techniques, deep holes with high straightness, roundness, and cylindricity can ultimately be obtained. This method can not only significantly improve the machining accuracy of products, but also has extremely important positive effects on increasing the yield rate of deep hole products and enhancing the economic benefits of enterprises. It has a very broad application prospect in the fields of navigation, aerospace, and other fields that require large-scale machining. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the principle of the three-line aiming and positioning method of the present invention.

[0036] Figure 2 It is a schematic diagram of the workpiece clamping calibrated based on the three-line aiming and positioning method of the present invention.

[0037] Figure 3 It is a process flow diagram of the multi-stage laser guiding hole machining of the present invention.

[0038] Figure 4 It is a schematic diagram of the laser small hole guiding to hit the middle hole of the present invention.

[0039] Figure 5 It is a schematic diagram of the middle hole guiding to expand the hole of the present invention.

[0040] Figure 6 It is a straightness diagram of the deep hole parts obtained under different machining methods.

[0041] In the figure: 1, target plate; 2, upper aiming point; 3, lower aiming point; 4, preset hole position; 5, laser holder; 6, upper laser sight; 7, lower laser sight; 8, machining laser; 9, aiming line one; 10, aiming line two; 11, aiming line three; 12, workpiece; 13, workpiece preset hole position one; 14, workpiece preset hole position two; 15, vacuum chamber; 16, gasket; 17, vacuum extraction outlet; 18, through-hole guiding hole of the workpiece; 19, focus one; 20, focus two; 21, focus three; 22, air plasma. DETAILED DESCRIPTION OF THE INVENTION

[0042] To make the technical means, creative features, achieved purposes, and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0043] Please refer to Figures 1-5 , the present invention provides the following technical solutions:

[0044] A deep hole machining process for reaming by using a multi-stage laser micro-hole guiding method with high straightness includes the following steps:

[0045] S1: Calibrate the laser deep hole machining equipment. The specific steps for calibrating the laser deep hole machining equipment are as follows:

[0046] S11: As Figure 1 shown, arrange the processing laser 8, the upper laser sight 6, and the lower laser sight 7 vertically on the same straight line of the bracket. The distance between the upper laser sight 6 and the lower laser sight 7 is l1, and the distance between the lower laser sight 7 and the processing laser 8 is l2, such as the aiming line one 9, aiming line two 10, and aiming line three 11 in Figure 1 .

[0047] S12: Make a target plate 1, and set an upper aiming point 2, a lower aiming point 3, and a preset hole position 4 on the target plate 1 on the same straight line. The distance between the upper aiming point 2 and the lower aiming point 3 is l1, and the distance between the lower aiming point 3 and the preset hole position 4 is l2. The spacing is the same as that between the upper and lower laser sights and the processing laser 8.

[0048] S13: Arrange the laser bracket 5 parallel to the target plate 1, and the distance between them is l. l is greater than the length of the deep hole of the workpiece to be machined. Make the upper laser sight 6 and the lower laser sight 7 on the laser bracket 5 aim at the upper aiming point 2 and the lower aiming point 3 on the target plate 1 respectively, and then fix the upper laser sight 6 and the lower laser sight 7.

[0049] S14: Adjust the calibration function of the processing laser 8 to align it with the preset hole position 4, and fix the processing laser 8 on the laser bracket 5. This is the initial position of the processing laser 8, and the calibration is completed.

[0050] S2: Based on the three-line aiming and positioning method, calibrate the workpiece clamping and repeat positioning. During multiple laser deep hole processes, it is necessary to clamp the workpiece based on the calibration of the laser, which is the key to ensuring high straightness control. The specific steps are as follows:

[0051] S21: As Figure 2 shown, align the preset hole position 4 on the target plate 1 with the workpiece preset hole position one 13 at one end of the workpiece 12, and fix the target plate 1 perpendicular to the corresponding axes of the workpiece preset hole position one 13 and the workpiece preset hole position two 14 on the workpiece 12.

[0052] S22: Adjust the laser bracket 5 so that the upper laser sight 6 and the lower laser sight 7 on the laser bracket 5 aim at the upper aiming point 2 and the lower aiming point 3 on the target plate 1 respectively. Start the calibration function of the processing laser 8 to align it with the workpiece preset hole position two 14 at the other end of the workpiece 12, and then fix the laser bracket 5, the workpiece 12, and the target plate 1. The clamping is completed.

[0053] S23: During the machining process, the target plate 1 and the workpiece 12 are relatively fixed. When laser focusing may cause the deviation of the machining line, in order to ensure the straightness of machining, by adjusting the laser holder 5, the upper laser sight 6 and the lower laser sight 7 are realigned with the upper aiming point 2 and the lower aiming point 3 on the target plate 1, and the machining laser 8 is naturally aligned with the workpiece preset hole position one 13 and the workpiece preset hole position two 14 on the workpiece 12, restoring the initial position and ensuring the straightness accuracy during the machining process.

[0054] S3: Multistage laser is used to machine small-diameter deep holes. The specific steps are as follows:

[0055] S31: As shown in Figure 3 (1), a vacuum chamber 15 is installed between the machining laser 8 and the workpiece 12. The vacuum chamber 15 and the workpiece 12 are assembled into a closed space through a gasket 16, and a vacuum outlet 17 is provided on the vacuum chamber 15;

[0056] S32: As shown in Figure 3 (1), adjust the focus of the machining laser 8 so that it falls on the workpiece preset hole position two 14;

[0057] S33: Adjust the machining laser 8 to the high-power drilling power gear position, start the machining laser 8 to drill holes, and the laser ablation products generate air plasma 22. Due to the negative pressure effect of the vacuum chamber 15, the air plasma 22 is discharged from the vacuum outlet 17. As shown in Figure 3 (2), a small hole with a certain depth is formed;

[0058] S34: Measure the depth of the bottom of the small hole, and adjust the laser focus of the machining laser 8 so that it falls near the bottom of the just-drilled small hole. The focus one 19, the focus two 20, and the focus three 21 are as shown in Figure 3 (1), (3), and (5) in the figure;

[0059] S35: Repeat step S33 to form a deeper two-stage small hole, as shown in Figure 3 (4) and Figure 3 (5) in the figure;

[0060] S36: Repeatedly perform steps S33, S34, and S35 to form a through hole with a small hole diameter d0≈2mm, as shown in Figure 3 (6) in the figure. The workpiece guiding hole 18 is formed through the workpiece by laser machining, which has high straightness but very low surface finish and roundness.

[0061] S4: Use the laser small hole guidance to ream the high-depth-diameter ratio hole one or more times. The specific steps are as follows:

[0062] S41: Install the workpiece with the small hole machined by laser on the middle hole drilling machine tool;

[0063] S42: Ream the middle hole using a gun drill. The diameter d1 of the middle hole satisfies d1 ≤ 3d0. The drill bit tip has a cutting edge with a taper of 120° to 150°, and the taper of the cutting edge ensures that the drill bit cuts along the direction of the small hole.

[0064] S43: On the basis of obtaining the middle hole by guiding and reaming the small hole, using the middle hole as a guiding hole, and reaming again using deep hole gun drills, BTA drills, ejector drills, DF deep hole drills, etc. The diameter d2 of the reaming again satisfies d2 ≤ 3d1, and finally a large-diameter deep hole with the required precision is machined.

[0065] When the middle hole is obtained by guiding and reaming the small hole, and then the middle hole is used as a guiding hole to ream to a larger-diameter deep hole, the control range of the change in the diameter of the reaming drill bit must be controlled within d m ≤ 3d m-1 , that is, the diameter of the reaming drill bit cannot exceed 3 times the diameter of the guiding hole. Otherwise, there will be no short board effect, the weak links are not obvious, and the effect of the small hole guiding hole is not good. In addition, the drill bit tip of the reaming drill bit should have a cutting edge with a taper of 120° to 150° and have an automatic hole-searching drilling function.

[0066] The benefits of deep hole machining are mainly reflected in the yield rate, and the yield rate has an exponential negative correlation with the depth-diameter ratio coefficient. According to incomplete statistics, when the hole depth exceeds 2 meters, the yield rate can reach 80%, which means the scrap rate is about 20%. For components that are processed with deep holes alone, the cost ranges from tens of thousands to hundreds of thousands. The reason for the high cost is closely related to the high scrap rate of large depth-diameter ratio drilling. Once a hole is scrapped, the entire part cannot be used. The deep hole machining process of the multi-stage laser micro-hole guiding and reaming method proposed by the present invention ensures the straightness of the hole through multi-stage laser machining, and then uses conventional drilling techniques to ream the hole to ensure the machining accuracy and quality. This process significantly improves the yield rate of deep hole machining, can reduce the scrap rate to less than 3%, and theoretically can even achieve a zero scrap rate. Therefore, this process can greatly reduce the machining cost, improve the economic benefits of the enterprise and the market competitiveness of the product.

[0067] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A deep hole machining process by an reaming method with multi-stage laser micro-hole guiding of high straightness, characterized in that It includes the following steps: S1: Calibrate the laser deep hole machining equipment; S2: Calibrate the workpiece clamping and repeat positioning based on the three-line aiming and positioning method; S3: Use multi-stage laser to machine small-diameter deep holes; S4: Use laser small hole guiding to enlarge the hole with a high depth-to-diameter ratio one or more times, and finally machine a large-diameter deep hole with the required accuracy.

2. The deep hole machining process of hole enlargement by multi-stage laser micro-hole guiding with high straightness according to claim 1, characterized in that, The specific steps for calibrating the laser deep hole machining equipment in S1 are as follows: S11: Vertically arrange the processing laser (8), the upper laser sight (6), and the lower laser sight (7) on the same straight line of the bracket. The distance between the upper laser sight (6) and the lower laser sight (7) is l1, and the distance between the lower laser sight (7) and the processing laser (8) is l2; S12: Set the upper aiming point (2), the lower aiming point (3), and the preset hole position (4) on the target plate (1) and on the same straight line. The distance between the upper aiming point (2) and the lower aiming point (3) is l1, and the distance between the lower aiming point (3) and the preset hole position (4) is l2; S13: Arrange the laser bracket (5) parallel to the target plate (1), and the distance therebetween is l, where l is greater than the deep hole length of the workpiece to be machined. Make the upper laser sight (6) and the lower laser sight (7) on the laser bracket (5) aim at the upper aiming point (2) and the lower aiming point (3) on the target plate (1) respectively, and then fix the upper laser sight (6) and the lower laser sight (7); S14: Adjust the calibration function of the processing laser (8) to align it with the preset hole position (4), and fix the processing laser (8) on the laser bracket (5). This is the initial position of the processing laser (8), and the calibration is completed.

3. A deep hole machining process by reaming method with multi-stage laser micro-hole guiding of high straightness according to claim 1, characterized in that The specific steps of S2 are as follows: S21: Align the preset hole position (4) on the target plate (1) with the workpiece preset hole position one (13) at one end of the workpiece (12), and fix the target plate (1) and the workpiece (12) perpendicular to the corresponding axes of the workpiece preset hole position one (13) and the workpiece preset hole position two (14); S22: Adjust the laser bracket (5) so that the upper laser sight (6) and the lower laser sight (7) on the laser bracket (5) aim at the upper aiming point (2) and the lower aiming point (3) on the target plate (1) respectively. Start the calibration function of the processing laser (8) to align it with the workpiece preset hole position two (14) at the other end of the workpiece (12), and then fix the laser bracket (5), the workpiece (12), and the target plate (1). The clamping is completed; S23: During the machining process, the target plate (1) and the workpiece (12) are relatively fixed. When laser focusing may cause the deviation of the machining line, in order to ensure the straightness of the machining, by adjusting the laser bracket (5), make the upper laser sight (6) and the lower laser sight (7) re-align with the upper aiming point (2) and the lower aiming point (3) on the target plate (1), and the processing laser (8) will naturally align with the workpiece preset hole position one (13) and the workpiece preset hole position two (14) on the workpiece (12).

4. A deep hole machining process by reaming method with high straightness multi-stage laser micro-hole guiding according to claim 1, characterized in that, The specific steps in S3 are as follows: S31: Install a vacuum chamber (15) between the processing laser (8) and the workpiece (12). The vacuum chamber (15) is assembled with the workpiece (12) through a gasket (16) to form a closed space. A vacuum extraction outlet (17) is provided on the vacuum chamber (15). S32: Adjust the focus of the processing laser (8) so that it falls on the preset hole position two (14) of the workpiece. S33: Start the processing laser (8) to drill a hole. The laser ablation products generate air plasma (22). Due to the negative pressure effect of the vacuum chamber (15), the air plasma (22) is discharged from the vacuum extraction outlet (17), forming a small hole with a certain depth. S34: Measure the depth of the bottom of the small hole, and adjust the laser focus of the processing laser (8) so that it falls near the bottom of the just-drilled small hole. S35: Repeat step S33 to form a deeper two-stage small hole. S36: Repeatedly perform steps S33, S34, and S35 to form a through small hole or a blind hole with a certain depth.

5. A deep hole machining process by reaming method with multi-stage laser micro-hole guiding of high straightness according to claim 4, characterized in that, The specific steps in S4 are as follows: S41: Install the workpiece with the small hole machined by laser on a middle-hole drilling machine tool. S42: Use a gun drill to enlarge the middle hole. The drill bit has a cutting edge with a taper of 120° - 150° at the top, and the taper of the cutting edge ensures that the drill bit cuts along the direction of the small hole. S43: On the basis of guiding the enlargement of the small hole to obtain the middle hole, use the middle hole as a guiding hole, and use a deep-hole gun drill, BTA drill, ejector drill, and DF deep-hole drill to perform re-enlargement again, and finally machine a large-diameter deep hole with the required accuracy.

6. The deep hole machining process by reaming method with multi-stage laser micro-hole guiding of high straightness according to claim 5, characterized in that, In S36, the diameter d0 of the small hole is approximately 2 mm.

7. A deep hole machining process by an underreaming method with multi-stage laser micro-hole guiding of high straightness according to claim 6, characterized in that, In S42, the diameter d1 of the middle hole is ≤ 3d0. In S43, the re-enlarged diameter d2 is ≤ 3d1.

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