A method for machining crankshaft internal splines using electric spark pulse method

Abstract

A method for machining the internal splines of a crankshaft using an electric spark pulse method. The present invention discloses a device for machining the internal splines of a crankshaft, comprising: a numerically controlled machine tool, wherein a fixing device is provided on the numerically controlled machine tool; a clamping device, wherein the clamping device is used to clamp the crankshaft, and wherein the fixing device is used to fix the clamping device on the numerically controlled machine tool; an electrode, wherein the electrode is controlled by the numerically controlled machine tool and is used for machining the internal splines of the crankshaft; a control interface, wherein the control interface is provided with at least an operation button for controlling the electrode, and is used to control the electrode to realize machining of the internal splines of the crankshaft; a power supply device, wherein the control interface is connected to the power supply device to realize power supply to the numerically controlled machine tool; when machining the internal splines of the crankshaft, the clamping device is fixed on the machine tool through the fixing device, and the clamping device clamps the end of the crankshaft, and after the center of the electrode is aligned with the center of the internal splines of the crankshaft, the control interface controls the electrode to machine the internal splines of the crankshaft. The present invention is used for machining internal splines, and the device is simple and the machining is convenient.

Description

Technical Field

[0001] The invention belongs to the technical field of crankshaft processing, and in particular relates to a method for processing crankshaft internal splines by utilizing an electric spark pulse method. Background Art

[0002] The crankshaft is the most important component in the engine. It bears the force transmitted from the connecting rod and converts it into torque, which is output through the crankshaft and drives other accessories on the engine to work.

[0003] The automotive air compressor belongs to the automotive brake system, and its main function is to provide compressed gas to the brake. To facilitate the transmission arrangement of the automotive engine, the automotive air compressor also bears the power transmission work of other components through its crankshaft, such as the steering pump, high-pressure oil pump, etc. The power transmission connection structure mainly has two structures: cross key and spline, among which spline is the most common, and the automotive air compressor end is internal spline.

[0004] At present, the light crankshafts used in engineering machinery and the automotive industry have many processing technical problems in the processing process due to the increasingly higher performance requirements of customers. For example, according to customer requirements, the newly produced crankshafts are short in length, small in diameter, light in weight, and have internal splines acting on one end. However, the existing gear shaping and spline pulling machine tools cannot process the internal splines of the crankshaft due to insufficient stroke, resulting in interference. In order to successfully complete the development of this project, it is necessary to break the traditional gear shaping and spline pulling processing and propose a method for machining the internal splines of the crankshaft using the electric spark pulse method. Summary of the invention

[0005] The purpose of the present invention is to provide a method for machining internal splines of a small crankshaft, which utilizes the principle of electrode machining inner holes, transfers the machining effect of the electrode to the crankshaft, and proposes a method for machining internal splines of the crankshaft using an electric spark pulse method.

[0006] In order to achieve the above technical effects, the present invention is implemented through the following technical solutions.

[0007] A method for machining crankshaft internal splines using an electric spark pulse method comprises the following steps:

[0008] S1 Crankshaft clamping: The end of the crankshaft away from the processing is clamped on the machine tool by a clamping device fixed on the machine tool;

[0009] S2 Crankshaft alignment: Align using a dial indicator to make the centerline of the crankshaft perpendicular to the machine tool;

[0010] S3 Center alignment: adjust the electrode on the machine tool to align it with the center of the internal spline on the crankshaft to be processed;

[0011] S4 internal spline processing: By adjusting the parameters on the machine tool, its output matches the electrode that matches the internal spline processing, and the motor can process the internal spline of the crankshaft.

[0012] In this technical solution, the parameters on the machine tool specifically include:

[0013] The first part is the parameters of the involute internal spline. For example, if you want to process a certain internal spline, the following parameter requirements must be met in the end:

[0014] The module m is 1, the number of teeth z is 17, the pressure angle α is 20°, the displacement coefficient x is 0.8, the major diameter Dw is Φ19.3min, and the minor diameter is Φ17 +0.1 0 The span bar Wi is 14.994 +0.071 0 , the diameter K of the measuring rod is Φ2.

[0015] The second part, the parameters of the involute external spline and the external spline inspection fixture, must ultimately meet the following parameter requirements:

[0016] The module m is 1, the number of teeth z is 17, the pressure angle α is 20°, the displacement coefficient x is 0.8, and the major diameter dl is Φ18.8 0 -0.052 , the diameter dr is Φ16.6 0 -0.1 , the span rod M2 is 21.026~21.100, and the measuring rod diameter U is Φ2.

[0017] Compared with the prior art, this technical solution innovatively applies the electric spark pulse machining method used for inner hole machining to internal spline machining, which is specifically as follows: when performing electric spark machining, the tool electrode and the workpiece are respectively connected to the two poles of the pulse power supply and immersed in the working fluid, or the working fluid is filled into the discharge gap. The tool electrode is fed to the workpiece through the gap automatic control system. When the gap between the two electrodes reaches a certain distance, the pulse voltage applied to the two electrodes breaks down the working fluid and generates spark discharge. A large amount of heat energy is instantly concentrated in the discharge microchannel, the temperature can be as high as more than 10,000 degrees Celsius, and the pressure also changes sharply, so that the local trace metal material on this point of the working surface is immediately melted and vaporized, and explosively splashed into the working fluid, quickly condensed, and formed solid metal particles, which are carried away by the working fluid. At this time, a tiny pit mark is left on the surface of the workpiece, the discharge is briefly paused, and the working fluid between the two electrodes returns to an insulating state. Then, the next pulse voltage breaks down at another point where the two electrodes are relatively close, generating spark discharge, and repeating the above process. In this way, although the amount of metal eroded by each pulse discharge is very small, due to the thousands of pulse discharges per second, more metal can be eroded, and a certain productivity is achieved. Under the condition of maintaining a constant discharge gap between the tool electrode and the workpiece, the workpiece metal is eroded while the tool electrode is continuously fed to the workpiece, and finally a shape corresponding to the shape of the tool electrode is processed. Therefore, as long as the shape of the tool electrode and the relative movement between the tool electrode and the workpiece are changed, various complex surfaces can be processed.

[0018] In this scheme, the specific steps of electrode processing are: through the processing of the internal spline sample, the rationality of the sample is tested with an external spline inspection fixture, thereby determining the accuracy of the electrode.

[0019] In this scheme, compared with the internal spline processing method in the prior art, the electric spark pulse method is used for processing, which has the advantages that it can process materials with high hardness, breaking the original gear shaping and tooth drawing processes that can only be processed before heat treatment. The electric spark pulse method can be processed before and after quenching heat treatment, and is not limited to the hardness of the material.

[0020] As a further improvement of the present invention, the step S1 also includes fixing the clamping device before the crankshaft is clamped. The fixing of the clamping device is specifically: fixing the matching magnetic clamping device on the machine tool through the magnetic suction device on the machine tool.

[0021] Taking full advantage of the machine tool's own magnetic disk, V-blocks and other components can be directly fixed, making preparations for the clamping of the crankshaft.

[0022] As a further improvement of the present invention, the step S1 further includes crankshaft fixing after the crankshaft is clamped and the step S2 before the crankshaft is aligned. The crankshaft fixing is specifically as follows: the clamping device is provided with a fixing piece, and after the clamping device clamps the end of the crankshaft, the fixing piece presses the crankshaft onto the clamping part of the clamping device.

[0023] Through further tightening, the stability of the crankshaft during the entire processing is ensured.

[0024] As a further improvement of the present invention, the crankshaft alignment in step S2 is specifically: aligning the crankshaft by marking the verticality with a dial indicator so that the crankshaft is clamped perpendicularly to the machine tool and the verticality error is 0.01 mm.

[0025] Adjust the verticality so that the crankshaft is perpendicular to the machine tool for easy processing.

[0026] As a further improvement of the present invention, the step S2 includes a safety distance adjustment after the crankshaft alignment step and before the center alignment step S3, and the safety distance adjustment is: adjusting the distance between the electrode on the machine tool and the crankshaft end to be processed so that the distance between the two is greater than or equal to 1 mm.

[0027] Adjust the safety distance to avoid misoperation during crankshaft processing, which may cause the crankshaft's internal spline processing to fail or other positions to be processed by misoperation.

[0028] As a further improvement of the present invention, after the safety distance adjustment step, it also includes electrode center alignment, and the electrode center alignment is specifically: using a dial indicator to align the four directions of the positive electrode to find the center of the positive electrode.

[0029] By aligning the center of the square electrode, the center of the electrode is aligned with the outer circle of the inner spline, thereby improving the machining accuracy. Specifically, the center of the electrode is connected to the rotating spindle on the machine tool, and the center of the spindle is aligned to find the center of the inner spline.

[0030] As a further improvement of the present invention, after the electrode center alignment step, the outer circle of the inner spline to be processed is also aligned. The alignment of the outer circle of the inner spline to be processed is specifically: aligning the outer circle of the inner spline hole by a dial indicator so that the runout is ≤0.01mm.

[0031] As a further improvement of the present invention, the center alignment in step S43 is specifically as follows: according to the diameter of the outer circle of the inner spline hole, the radius of the center is obtained so that the center of the electrode is aligned with the center of the inner spline of the crankshaft.

[0032] Specifically, after the electrode and the crankshaft center are aligned, the runout of the outer circle is within 0.01mm through the dial indicator. At this time, the reference outer circle center of the inner spline is aligned, the electrode moves the radius value, and the center is aligned. In this embodiment, the spindle on the machine tool is connected to the electrode, and the meter is sucked on the electrode spindle. The runout of the outer circle of the inner spline of the crankshaft is within 0.01mm. The verticality has been aligned before, indicating that the spindle and the crankshaft are on the same line with an error of 0.01mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic structural diagram of a crankshaft internal spline machining device provided by the present invention;

[0034] Figure 2 A schematic diagram of the structure of the clamping device provided by the present invention;

[0035] Figure 3 A schematic diagram of the axial cross-sectional structure of the internal spline provided by the present invention;

[0036] In the figure:

[0037] 1. EDM machine; 2. Magnetic disk; 3. V-block; 4. Crankshaft; 5. Electrode; 10. Internal spline. DETAILED DESCRIPTION

[0038] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0039] Refer to the attached Figure 1-3 As shown, a method for machining crankshaft internal splines using an electric spark pulse method in the present invention comprises the following steps:

[0040] S1 Crankshaft clamping: The end of the crankshaft away from the processing is clamped on the machine tool by a clamping device fixed on the machine tool;

[0041] S2 Crankshaft alignment: Align using a dial indicator to make the centerline of the crankshaft perpendicular to the machine tool;

[0042] S3 Center alignment: adjust the electrode on the machine tool to align it with the center of the internal spline on the crankshaft to be processed;

[0043] S4 internal spline processing: By adjusting the parameters on the machine tool, its output matches the electrode that matches the internal spline processing, and the motor can process the internal spline of the crankshaft.

[0044] Compared with the prior art, this technical solution innovatively applies the electric spark pulse machining method used for inner hole machining to internal spline machining, which is specifically as follows: when performing electric spark machining, the tool electrode and the workpiece are respectively connected to the two poles of the pulse power supply and immersed in the working fluid, or the working fluid is filled into the discharge gap. The tool electrode is fed to the workpiece through the gap automatic control system. When the gap between the two electrodes reaches a certain distance, the pulse voltage applied to the two electrodes breaks down the working fluid and generates spark discharge. A large amount of heat energy is instantly concentrated in the discharge microchannel, the temperature can be as high as more than 10,000 degrees Celsius, and the pressure also changes sharply, so that the local trace metal material on this point of the working surface is immediately melted and vaporized, and explosively splashed into the working fluid, quickly condensed, and formed solid metal particles, which are carried away by the working fluid. At this time, a tiny pit mark is left on the surface of the workpiece, the discharge is briefly paused, and the working fluid between the two electrodes returns to an insulating state. Then, the next pulse voltage breaks down at another point where the two electrodes are relatively close, generating spark discharge, and repeating the above process. In this way, although the amount of metal eroded by each pulse discharge is very small, due to the thousands of pulse discharges per second, more metal can be eroded, and a certain productivity is achieved. Under the condition of maintaining a constant discharge gap between the tool electrode and the workpiece, the workpiece metal is eroded while the tool electrode is continuously fed to the workpiece, and finally a shape corresponding to the shape of the tool electrode is processed. Therefore, as long as the shape of the tool electrode and the relative movement between the tool electrode and the workpiece are changed, various complex surfaces can be processed.

[0045] In this embodiment, the parameters on the machine tool specifically include:

[0046] First, the parameters of the involute internal spline. For example, if you want to process a certain internal spline, it must eventually meet the following parameter requirements:

[0047] The module m is 1, the number of teeth z is 17, the pressure angle α is 20°, the displacement coefficient x is 0.8, the major diameter Dw is Φ19.3min, and the minor diameter is Φ17 +0.1 0 The span bar Wi is 14.994 +0.071 0 , the diameter K of the measuring rod is Φ2.

[0048] Secondly, the parameters of the involute external spline and external spline inspection fixture must ultimately meet the following parameter requirements:

[0049] The module m is 1, the number of teeth z is 17, the pressure angle α is 20°, the displacement coefficient x is 0.8, and the major diameter dl is Φ18.8 0 -0.052 , the diameter dr is Φ16.6 0 -0.1 , the span rod M2 is 21.026~21.100, and the measuring rod diameter U is Φ2.

[0050] In this scheme, the specific steps of electrode processing are: through the processing of the internal spline sample, the rationality of the sample is tested with an external spline inspection fixture, thereby determining the accuracy of the electrode.

[0051] In this scheme, compared with the internal spline processing method in the prior art, the electric spark pulse method is used for processing, which has the advantages that it can process materials with high hardness, breaking the original gear shaping and tooth drawing processes that can only be processed before heat treatment. The electric spark pulse method can be processed before and after quenching heat treatment, and is not limited to the hardness of the material.

[0052] As a further improvement of the present invention, the step S1 also includes fixing the clamping device before the crankshaft is clamped. The fixing of the clamping device is specifically: fixing the matching magnetic clamping device on the machine tool through the magnetic suction device on the machine tool.

[0053] Taking full advantage of the machine tool's own magnetic disk, V-blocks and other components can be directly fixed, making preparations for the clamping of the crankshaft.

[0054] Furthermore, the step S1 of crankshaft clamping and the step S2 of crankshaft alignment also include crankshaft fixing, and the crankshaft fixing is specifically as follows: the clamping device is provided with a fixing piece, and after the clamping device clamps the crankshaft end, the fixing piece presses the crankshaft onto the clamping part of the clamping device.

[0055] Through further tightening, the stability of the crankshaft during the entire processing is ensured.

[0056] Specifically, the crankshaft alignment in step S2 is specifically: aligning by marking the verticality with a dial indicator so that the verticality of the dial indicator is less than or equal to 0.01 mm.

[0057] Adjust the verticality so that the crankshaft is perpendicular to the machine tool for easy processing.

[0058] As a further improvement of the present invention, the step S2 includes a safety distance adjustment after the crankshaft alignment step and before the center alignment step S3, and the safety distance adjustment is: adjusting the distance between the electrode on the machine tool and the crankshaft end to be processed so that the distance between the two is greater than or equal to 1 mm.

[0059] Adjust the safety distance to avoid misoperation during crankshaft processing, which may cause the crankshaft's internal spline processing to fail or other positions to be processed by misoperation.

[0060] As a further improvement of the present invention, after the safety distance adjustment step, it also includes electrode center alignment, and the electrode center alignment is specifically: using a dial indicator to align the four directions of the positive electrode to find the center of the positive electrode.

[0061] By aligning the center of the square electrode, the center of the electrode is aligned with the outer circle of the inner spline, thereby improving the machining accuracy. Specifically, the center of the electrode is connected to the rotating spindle on the machine tool, and the center of the spindle is aligned to find the center of the inner spline.

[0062] Furthermore, after the electrode center alignment step, the process also includes aligning the outer circle of the inner spline to be processed. The alignment of the outer circle of the inner spline to be processed is specifically as follows: aligning the outer circle of the inner spline hole by a dial indicator so that the runout is ≤0.01 mm.

[0063] As a further improvement of the present invention, the center alignment in step S43 is specifically as follows: according to the diameter of the outer circle of the inner spline hole, the radius of the center is obtained so that the center of the electrode is aligned with the center of the inner spline of the crankshaft.

[0064] Specifically, after the electrode and the crankshaft center are aligned, the runout of the outer circle is within 0.01mm through the dial indicator. At this time, the reference outer circle center of the inner spline is aligned, the electrode moves the radius value, and the center is aligned. In this embodiment, the spindle on the machine tool is connected to the electrode, and the meter is sucked on the electrode spindle. The runout of the outer circle of the inner spline of the crankshaft is within 0.01mm. The verticality has been aligned before, indicating that the spindle and the crankshaft are on the same line with an error of 0.01mm.

[0065] Embodiment 1:

[0066] See attached Figure 1 As shown, the present invention needs to be processed to obtain the attached Figure 3 The internal spline 10 in the embodiment of the present invention is specifically provided by attaching Figure 1-2 The equipment in the invention adopts an existing MP-50 type electric discharge machining machine 1, on which a magnetic disk 2 is arranged, and a control interface thereof is provided with a magnetic disk control button and a control button for controlling a motor 5. At the same time, an existing V-block 3 is adopted, which is magnetically attracted to the electric discharge machining machine 1 through the magnetic disk 2, and then controls the relevant parameters of the electrode 5 to realize the processing of the internal spline 10.

[0067] In this embodiment, the adjustment of the parameters related to the electric spark can refer to the internal hole processing technology, which are all known technologies, and then adjust to appropriate parameters to achieve the processing of the internal splines of the crankshaft.

[0068] During processing, the present invention mainly adjusts the following parameters:

[0069] First, the parameters of the involute internal spline. For example, if you want to process a certain internal spline, the following parameters must be controlled in the end:

[0070] Module m, number of teeth z, pressure angle α, displacement coefficient x, major diameter Dw, minor diameter Φ, span rod Wi, measuring rod diameter K.

[0071] Second, the parameters of the involute external spline and external spline inspection fixture should ultimately control the following parameters:

[0072] Module m, number of teeth z, pressure angle α, displacement coefficient x, major diameter dl, minor diameter dr, span rod M2, measuring rod diameter U.

[0073] In the present invention, the internal spline of the crankshaft is processed by electrospark. In the prior art, the main purpose and application scope of the electrospark forming machine tool is that the equipment is mainly used for processing the complex cavities and curved surface shapes of various conductors such as various molds and precision parts manufacturing. It has the characteristics of high processing accuracy, high finish and high speed. The electrospark forming machine tool has a beautiful appearance design, a reasonable and compact structural design, and a solid and strong mechanical structure. The machine tool has extremely strong practical functions in terms of structural characteristics. It is mainly used for internal hole processing, and the internal spline processing of the crankshaft, especially the crankshaft in automobile braking, is mostly processed by the gear shaping and tooth drawing process before heat treatment. It has restrictions on the processing materials and is difficult to process crankshafts with high hardness and light weight. The present invention innovatively uses the electrospark pulse processing method used for internal hole processing for internal spline processing, which provides a new processing method for crankshaft internal spline processing.

[0074] The crankshaft of the present invention is mainly used in outboard motors and unmanned aerial vehicles. The development of the crankshaft is of great significance for further developing the aviation field and the market for engineering machinery engine parts.

[0075] In the present invention, the main parameters of the crankshaft are: the crankshaft length is 390-440mm, the weight is 10-12Kg, the main journal diameter is φ60mm, the connecting rod journal diameter is φ50mm, the thrust opening is 24mm, and the turning radius R46mm.

[0076] The method of the present invention, because it adopts the principle of electric spark pulse processing, can be used for crankshaft internal spline processing before or after quenching, without considering the hardness; while the internal spline processing method in the existing traditional gear shaping and gear pulling technology can only be used for crankshaft internal spline processing when the hardness is small before quenching, and cannot be processed after quenching due to the high hardness. Therefore, compared with the prior art, the crankshaft internal spline processing method of the present invention does not need to consider the hardness and has a wider range of applications.

[0077] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is determined by the attached claims and their equivalents.

Claims

1. A method for machining crankshaft internal splines using an electric spark pulse method, characterized in that: The following steps are involved: S1 Crankshaft clamping: The end of the crankshaft away from the processing is clamped on the machine tool by a clamping device fixed on the machine tool; S2 Crankshaft alignment: Align using a dial indicator to make the centerline of the crankshaft perpendicular to the machine tool; S3 Center alignment: adjust the electrode on the machine tool to align it with the center of the internal spline on the crankshaft to be processed; S4 internal spline processing: By adjusting the parameters on the machine tool, its output matches the electrode that matches the internal spline processing, and the motor can process the internal spline of the crankshaft.

2. The method for machining crankshaft internal splines using an electric spark pulse method according to claim 1, characterized in that: The step S1 before the crankshaft is clamped also includes fixing the clamping device, and the fixing of the clamping device is specifically: A magnetic clamping device matching with the machine tool is fixed on the machine tool through the magnetic suction device on the machine tool.

3. The method for machining crankshaft internal splines using an electric spark pulse method according to claim 1, characterized in that: After the crankshaft is clamped in step S1 and before the crankshaft is aligned in step S2, the crankshaft is fixed. The crankshaft is fixed specifically as follows: The clamping device is provided with a fixing piece. After the clamping device clamps the end of the crankshaft, the fixing piece presses the crankshaft onto the clamping part of the clamping device.

4. The method for machining crankshaft internal splines by using electric spark pulse method according to claim 1, characterized in that: The crankshaft alignment in step S2 is specifically as follows: aligning the crankshaft by marking the verticality with a dial indicator so that the crankshaft is vertically clamped to the machine tool and the verticality error is less than or equal to 0.01 mm.

5. The method for machining crankshaft internal splines by using electric spark pulse method according to claim 1, characterized in that: The step S2 includes a safety distance adjustment after the crankshaft alignment step and the step S3 includes a center alignment step. The safety distance adjustment is to adjust the distance between the electrode on the machine tool and the end of the crankshaft to be processed so that the distance between the two is greater than or equal to 1 mm.

6. The method for machining crankshaft internal splines by using electric spark pulse method according to claim 5, characterized in that: After the safety distance adjustment step, the method further includes aligning the electrode center. Specifically, the electrode center alignment includes: using a dial indicator to locate the four directions of the positive electrode to locate the center of the positive electrode.

7. The method for machining crankshaft internal splines by using electric spark pulse method according to claim 6, characterized in that: After the electrode center alignment step, the method further includes aligning the outer circle of the inner spline to be processed. The alignment of the outer circle of the inner spline to be processed is specifically: aligning the outer circle of the inner spline hole by a dial indicator so that the runout is ≤0.01mm.

8. The method for machining crankshaft internal splines by using electric spark pulse method according to claim 7, characterized in that: The center alignment in step S3 is specifically as follows: according to the diameter of the outer circle of the inner spline hole, the radius of the center is obtained so that the center of the electrode is aligned with the center of the inner spline of the crankshaft.

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