JPH11179605A - Non-circular boring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To work a complicated non-circular internal surface shape at a high speed and in high accuracy, by eliminating the necessity for manufacturing a master and a fixing jig in accordance with a work shape. SOLUTION: In a device applying non-circular boring work to a workpiece by mounting a boring tool 4 in a spindle 1 through a tool eccentric vibration device, synchronously with rotation of the spindle, and eccentrically vibrating the boring tool, eccentric vibration of the boring tool 4 is performed by a piezoelectric element 5. Here, a tool holder 3 is mounted in the spindle 1 through an elastic deformation unit 2, and deformation vibration is applied thereto by the piezoelectric element 5, so as to perform eccentric vibration of the boring tool 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boring process capable of cutting a cross section perpendicular to an axis into a non-circular shape in boring of a cylindrical inner surface of a machine part, for example, when drilling a piston pin hole in a piston. Related to the device.

[0002]

2. Description of the Related Art In recent pistons for internal combustion engines,
The pressure on the pin hole tends to increase more and more, and the pin hole whose cross section perpendicular to the center axis of the pin hole is a perfect circle cannot withstand this pressure as before, and it is not uncommon for cracks to occur. . In order to solve this, a pin hole having a non-circular cross section perpendicular to the axis has recently been adopted.

[0003] In order to perform non-circular boring,
Heretofore, processing methods such as a copying processing method, a hydraulic servo method, a servomotor method, and a work swinging method have been used. The outline and problems of each of these systems are briefly described below.

In the copying method, an elastically deformable body is provided between a main spindle and a tool holder, and the elastically deformable body is deformed in one direction perpendicular to the axis by a spring force or the like, so that an amount of the deformation with respect to the axis of the main spindle is reduced. The axis of the tool holder is shifted. In addition, the stylus and the tool (tool) are installed in the direction in which the axis of the tool holder is shifted. On the other hand, a master having a non-circular cylindrical inner surface to be machined is fixed on the outer peripheral bed of the tool holder concentrically with the spindle. At this time, the stylus fixed to the tool holder is pressed against the inner surface of the master by a spring force or the like provided on the elastically deformable body. At the time of machining, after the work is mounted concentrically with the spindle, the tool holder rotates while the stylus is pressed against the master inner surface due to deformation of the elastic deformation body, so the tool holder and tool follow the master inner surface with respect to the spindle. Rotate while vibrating in the radial direction. As a result, the inner surface of the work is processed into a non-circular shape.

[0005] The problems of such a copying process are that it takes a lot of time and cost to manufacture and set up a master and a fixing jig (on a bed), and that the copying of the master can be followed. There is a limitation on the processing shape (only a specific ellipse can be processed), it is not possible to cope with a shape having a large change, and it is difficult to perform high-speed rotation processing.

In the hydraulic servo system, an elastically deformable body is provided between a spindle and a tool holder, and the elastically deformable body is deformed by a hydraulic pressure in a predetermined direction in a direction perpendicular to the axis, so that only an amount of deformation with respect to the axis of the spindle is provided. The axis of the tool holder is shifted. Also, the tool is installed in a direction to shift the axis of the tool holder. In this case, unlike the copying method,
In order to perform the non-circular machining, it is necessary to store the amount of displacement of the tool (the amount of deformation of the elastically deformable body) for each position in the axial direction and the rotation angle, and to perform computer control of the hydraulic pressure to execute the processing. In order to more accurately perform actual tool displacement when a cutting force is applied, feedback control of the tool displacement is performed.

The problems with such a hydraulic servo system are that the response of the hydraulic cylinder by the hydraulic control is low, and the oil temperature changes because the oil pressure changes due to the change in the oil temperature, and the oil temperature must be controlled. This management is difficult, and high-speed rotation processing is difficult for these reasons.

The servomotor system is such that the elastically deformable body in the hydraulic servo system is deformed by a servomotor attached to the main shaft, and is similar to the hydraulic servo system except for this point. The problem with such a servo motor method is that the motor frequently rotates in the forward and reverse directions, thereby increasing the inertia of the motor and causing elastic deformation of the ball screw and the feed table. And the responsiveness is deteriorated, and finally the processing accuracy is also deteriorated.

In the above three methods, the work is fixed and the tool holder is vibrated in the radial direction over the entire range. On the other hand, the work oscillating method vibrates (oscillates) the work.
It is intended to be. The swing of the work can be performed by means of copying, hydraulic pressure, a servomotor, or the like, in principle, as in the above three methods. The problem with such a work swinging method is that, in principle, it is actually difficult even if swinging at all angles is possible, and only swinging (vibration) can be performed in one direction. That is, it is limited (only a specific ellipse can be processed), and the weight of the work and its mounting jig increases, and the inertia force due to the swing increases, so that it cannot cope with high-speed rotation of the main shaft.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to eliminate the need to manufacture a master or a fixing jig according to a processing shape. Another object of the present invention is to provide a non-circular boring apparatus capable of processing a complicated non-circular inner surface shape at high speed and with high accuracy.

[0011]

Means for Solving the Problems The above-mentioned problems are mainly solved by
An eccentric vibration of a boring tool by a piezoelectric element in a device that mounts a boring tool via a tool eccentric vibration device and eccentrically vibrates the boring tool in synchronization with the rotation of the spindle Can be achieved by a non-circular boring apparatus. In that case, a tool holder is attached to the main shaft via an elastic deformable body, and the elastic deformable body is deformed and vibrated by the piezoelectric element, thereby causing eccentric vibration of the boring tool. Normally, the vibration of the piezoelectric element is applied in one axis direction perpendicular to the mounting axis of the boring tool, but in some cases, the vibration may be applied in two axial directions perpendicular to the mounting axis of the boring tool. . The eccentric vibration of the boring tool may be performed by a magnetostrictive element instead of the piezoelectric element. Further, it is desirable to perform feedback control by detecting the amount of displacement of the elastic deformation body in a direction perpendicular to the axis by a displacement sensor.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic view of an embodiment of a non-circular boring machine according to the present invention, FIG. 2 is a perspective view showing a configuration of a spindle tip portion, and FIG. 3 is a control of the machining device shown in FIG. System diagram, FIG. 4 is a schematic view of another embodiment of the non-circular boring apparatus according to the present invention, FIG. 5 is a perspective view showing a configuration of a spindle tip portion of still another embodiment, and FIG. , FIG.
7 is an enlarged view of the embodiment shown in FIG.
5 is a graph showing an example of processing a piston pin hole by the non-circular boring apparatus according to the present invention.

1 to 3, reference numeral 1 denotes a main shaft of a processing apparatus;
2 is an elastically deformable body attached to the tip of the main shaft, 3 is a tool holder attached to the tip of the elastically deformable body, 4 is a boring tool attached to the tool holder, 5 is a piezoelectric element provided inside the elastically deformable body 2 ( Or a magnetostrictive element), 6 is a displacement sensor for detecting the amount of displacement of the elastic deformation body 2 in the direction perpendicular to the axis, 7 is a motor for rotating the spindle, 8 is a rotary encoder for detecting the rotation angle of the spindle, and 9 is an output of the displacement sensor 6. A slip ring for taking out and supplying a drive current to the piezoelectric element 5;
Is an NC device for controlling machining feed and other operations, and 12 is N
Based on the control signal from the C device 11 and the output signals from the displacement sensor 6 and the rotary encoder 8, the piezoelectric element 5
, A computer that controls the processing of the non-circular boring shape, 13 is a D / A converter, 14 is an A / D converter, and 15 is a computer that controls the operation of the piezoelectric element based on a control signal from the computer 12. A piezoelectric element controller for controlling, a piezoelectric element driver 16 for supplying a drive current to the piezoelectric element 5, a feed table 21,
2 is a servo motor for driving the feed table in the X-axis direction;
Is a servomotor for driving in the Y-axis direction, and 24 is a work to be subjected to boring.

In the above embodiment, the piezoelectric element or the magnetostrictive element 5 is assembled to the elastically deformable body 2 attached to the main shaft 1, and the rotational speed of the main shaft 1 detected by the rotary encoder 8 and the piezoelectric element or the magnetostrictive element 5 An output voltage controlled according to a desired non-circular locus is applied via the slip ring 9 so as to be synchronized with the rotation angle. As a result, the elastically deformable body 2 is pressurized and deformed in one direction perpendicular to the axis (the direction in which the tool 4 is attached), and the tool holder 3 and the tool 4 integrated with the elastically deformable body are moved by the amount of deformation of the elastically deformable body. Displace in the direction perpendicular to the axis. That is, as shown in FIGS. 2 and 3,
Concave grooves 2a and 2b are formed on the outer wall surface of the elastically deformable body 2, and the distal end side of these grooves is displaced in the vertical direction in the figure by the expansion and contraction vibration of the piezoelectric element 5, whereby the tool holder is rotated by the rotation of the main shaft 1. 3 rotates eccentrically. The desired non-circular boring can be performed by rotating the main shaft while controlling the amount of tool displacement in the direction perpendicular to the axis using the NC device 11 and the computer 12 for each axial position and rotation angle. . The work 24 is, for example, a piston in the example shown in FIG. 3, and shows a state in which a boring process is performed on a pin hole 24 a having a non-circular cross section. In order to perform more accurate processing, the elastic deformable body 2
Is detected by the displacement sensor 6 in the direction perpendicular to the axis of
It is desirable to perform feedback control.

This operation will be described below with reference to specific processing steps. (1) The work 24 is set on the feed table 21. (2) The spindle rotation motor 7 is rotated. As a result, the elastically deformable body 2 and the tool holder 3 attached to the spindle 1
Also rotate. (3) The feed table 21 is moved toward the spindle by the servo motor 22. (4) When the work 24 reaches a predetermined position near the tool 4 attached to the tool holder 3, a command is sent from the computer 12 to the piezoelectric element controller 15 to operate the piezoelectric element driver 16. (5) The piezoelectric element driver 16 supplies a drive current to the piezoelectric element 5 provided inside the elastic deformation body 2 through the slip ring 9. (6) The piezoelectric element 5 is displaced by this electric current,
To transform. As a result, the tool holder 3 attached to the distal end surface of the elastically deformable body and the tool 4 attached thereto
Also displaces. (7) The rotation angle position of the main shaft is detected by the rotary encoder 8 attached to the main shaft 1, and the displacement amount of the piezoelectric element is changed according to the division angle position of the processing cross section based on the shape stored in the computer 12 in advance. Process any shape. (8) The amount of displacement of the elastically deformable body 2 is detected by the displacement sensor 6 and the output signal is sent to the computer 12 through the slip ring 9 to feedback-control the operation of the piezoelectric element controller 15 to improve the processing accuracy. .

In the embodiment shown in FIG. 4, the piezoelectric element 5 is provided outside the elastically deformable body 2 so as to deform the elastically deformable body. That is, a supporting column 1 a is provided on the main shaft 1, and a bearing 10 attached to the base of the tool holder 3 is provided.
The piezoelectric element 5 is inserted between the support 1a and the support 1a, and the tool holder 3 is displaced in a direction perpendicular to the axis thereof by expansion and contraction of the piezoelectric element.

Next, in the embodiment shown in FIGS. 5 and 6, the vibration of the piezoelectric element is applied in two axial directions perpendicular to the axis of the tool holder 3. FIG. That is, the support 1a is attached to the main shaft 1.
And 1b, and the piezoelectric elements 5A and 5B are inserted between the bearing 10 attached to the base of the tool holder 3 and the columns 1a and 1b, respectively, so that the output directions of the piezoelectric elements 5A and 5B become 90 °, and elastic deformation is performed. The body 2 is deformed under pressure in two axial directions. The amount of deformation is detected by the displacement sensors 6A and 6B, and the axis of motion of the tool is biaxially controlled while performing feedback control. According to this method, a response twice as high as the driving frequency of the elastically deformable body can be obtained, so that stable non-circular boring at a higher rotation speed can be performed as compared with the one-axis control.

FIG. 7 shows an example in which an elliptical piston pin hole P having a long diameter of 36 mm is machined by using the non-circular boring machine according to the present invention. On the graph, the position at 0 ° is the head side of the piston, and the position at 180 ° is the skirt side.

[0019]

The non-circular boring device according to the present invention is
It has the following advantages over the conventional method. (1) In contrast to the copying method, there is no need to manufacture a copying master, etc., and costs are reduced, including shortening of the setup change time. Shapes with large changes can be processed, and high-speed rotation processing is also possible. (2) Responsiveness of pressurization is better than hydraulic servo system compared to hydraulic pressure. Since no oil is used, accurate control is possible without being affected by the oil temperature. For these reasons, it is possible to machine even a shape with a large change, and high-speed rotation machining is also possible. For the same reason, the processing accuracy is particularly high in the case of the same shape and the same rotation processing. (3) Compared to the servo motor method, since there is no frequent forward / reverse rotation of the motor, accurate control is possible without increasing the inertia of the motor and elastic deformation of the ball screw and feed table. Therefore, it is possible to process even a shape having a large change, and high-speed rotation processing is also possible. Further, the processing accuracy in the case of the same shape and the same rotation processing is high. (4) The tool can be freely displaced in all directions of 360 ° with respect to the work swinging method, so that the workable shape is not limited and various non-circular workings are possible. As compared with the swinging of a heavy work or the like, if the shape is the same, the rotation processing can be performed at a higher speed.

As described above, according to the present invention, it is not necessary to manufacture a master or a fixing jig corresponding to a processing shape, and a complicated non-circular inner surface shape can be processed at high speed and with high precision. Thus, it is possible to provide a non-circular boring apparatus having many advantages.

The present invention is not limited to the above embodiment, and the shape and mounting method of the elastically deformable body, the mounting form of the piezoelectric element or the magnetostrictive element for the elastic deformation body, and the like can be appropriately changed as necessary. Therefore, the present invention covers all modifications within the scope of the object that are easily conceived by those skilled in the art from the above description.

[Brief description of the drawings]

FIG. 1 is a schematic view of one embodiment of a non-circular boring apparatus according to the present invention.

FIG. 2 is a perspective view showing a configuration of a spindle tip portion.

FIG. 3 is a control system diagram of the processing apparatus shown in FIG. 1;

FIG. 4 shows another non-circular boring apparatus according to the present invention.
FIG. 3 is a schematic diagram of one embodiment.

FIG. 5 is a perspective view showing a configuration of a spindle tip portion of still another embodiment.

FIG. 6 is an enlarged view of the embodiment shown in FIG. 5 as viewed from a tip end side of a spindle.

FIG. 7 is a graph showing a processing example of a piston pin hole by the non-circular boring apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main shaft of processing apparatus 1a, 1b Column 2 Elastic deformation body 2a, 2b Groove 3 Tool holder 4 Boring tool 5 Piezoelectric element (or magnetostrictive element) 6 Displacement sensor 7 Motor for main shaft rotation 8 Rotary encoder for rotation angle detection 9 Slip Ring 10 Bearing 11 NC device 12 Computer 13 D / A converter 14 A / D converter 15 Piezoelectric element controller 16 Piezoelectric element driver 21 Feed table 22 Servomotor for X-axis direction drive 23 Servomotor for Y-axis direction drive 24 Work

Claims (6)

[Claims] 1. A boring tool (4) is attached to a main shaft (1) via a tool eccentric vibration device, and the boring tool is eccentrically vibrated in synchronization with the rotation of the main shaft to form a non-circular boring work on a workpiece. The non-circular boring machine described above, wherein the eccentric vibration of the boring tool (4) is performed by the piezoelectric element (5). 2. A boring tool by attaching a tool holder (3) to a main shaft (1) via an elastic deformable body (2) and deforming and vibrating the elastic deformable body (2) by a piezoelectric element (5). The non-circular boring apparatus according to claim 1, wherein the eccentric vibration of (4) is performed. 3. The non-circular boring apparatus according to claim 1, wherein the vibration of the piezoelectric element is applied in one axial direction perpendicular to a mounting axis of the boring tool. 4. The non-circular boring according to claim 1, wherein the vibration of the piezoelectric element is applied in two axial directions perpendicular to the mounting axis of the boring tool. apparatus. 5. The non-circular boring according to claim 1, wherein eccentric vibration of the boring tool (4) is performed by a magnetostrictive element instead of the piezoelectric element (5). Processing equipment. 6. The method according to claim 1, wherein a feedback control is performed by detecting a displacement of the elastic deformation body in a direction perpendicular to the axis by a displacement sensor. Circular boring machine.