KR920006656B1 - Machine tools - Google Patents

Abstract

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Description

Machine tools

1 is a schematic view of a first embodiment of a machine tool,

2 is a schematic view of differently combining the tools of FIG. 1 with respect to the workpiece,

3 is a schematic view of a second embodiment of a machine tool,

4 is a perspective view of a first form of a DC linear motor used in the machine tool of FIG.

5 is a cross-sectional view of a tool positioning device suitable for the converter of FIG. 4,

6 is a perspective view of a second form of a DC linear motor used as a transducer in the machine tool of FIG.

The present invention relates to a machine tool for machining a workpiece to an inconsistent surface contour, in which a machining angle of the tool is required where there is a comparative rotation between the tool and the workpiece. And a control device for generating an electrical output signal that is a function of the non-uniform surface appearance required, and comprising a tool actuator and a tool for operating the tool by said output signal. In known machine tools of this type, the tool is carried by an electric motor via a lead screw and fitted into a tool holder which runs on a slide.

Such machine tools are applicable to a wide variety of workpieces from a wide range of cutting forces.

The disadvantage of this conventional machine tool is that the inertia of the slide and the transmission structure by the drive from the motor to the slide severely limit the speed of the rotating workpiece that can be machined when the tool position must be changed during machining. to be. This is because there is a speed at which the slide cannot act on the position signal quickly enough even if the rotational speed of the workpiece is increased or the movement speed of the tool is increased, so that the tool is not in the required place at the required time and the required contour is machined. Will not be.

This is especially true when the position of the tool has to be changed a number of times within the rotation range of the workpiece or between rotations.

The present invention is therefore characterized in that the tool actuator comprises a transducer connected to a control device for directly converting the electric force output signal into a corresponding linear motion, the tool being connected directly to the transducer for linear motion, which is not constant required. The workpiece with a non-surface contour.

Newer features or combinations of features of the present invention will be described in detail in two embodiments of the accompanying drawings and the factory machine.

Referring first to FIG. 1 and FIG. 2, the machine tool includes a frequency generator 10 and a frequency modulator 11 under pressure from the control device 12. The signal generated from the frequency modulator 11 is transmitted to the ultrasonic transducer 13, where the ultrasonic transducer is in the form of piezoelectric crystals or crystals, where the signal is magnitude in accordance with the power of the signal and related to the natural frequency of the crystals or crystals. Is converted into linear ultrasonic vibrations. These linear vibrations are transmitted to a toolholder 14 which supports a tool 15 for the machining of a rotating workpiece that is rotated by a driver 21. The toolholder 14 is connected to a driver 22 which moves the holder 14 in the axial direction of the workpiece 16 at a predetermined constant speed.

However, it can be seen that the workpiece 16 can be stabilized during machining, and the tool 15 rotates around the workpiece 16 on the rotating head.

The angle detector 17 generates a signal proportional to the angular position of the workpiece 16 during rotation, and the axis sensor 19 generates a signal proportional to the axial position of the toolholder along the axis of rotation of the workpiece 16. . These signals are fed back to the controller 12.

The frequency generator 10 generates a signal of 5 KHz to 100 KHz, preferably an ultrasonic frequency, that is, 15 KHz to 30 KHz. The maximum power of the signal corresponds to about 5KW of ultrasonic power. One of the main effects of the application of this frequency vibration to the toolholder is to increase the cutting ratio of the tool. The cutting ratio (along with other constants held constant, proportional to the depth of the cut in proportion to the ultrasonic vibration) is proportional to the power of the signal applied to the ultrasonic transducer. Since this signal is a constant frequency, in fact this means that the depth of cut is proportional to the magnitude of the signal.

The control device 12 receives information from the input device 23 according to the required surface appearance of the workpiece 16. The control device generates a constant electrical output signal of magnitude proportional to the required radius at the required time (i.e., the desired angular position around the workpiece and the desired axial position of the workpiece). In the generation of this signal, the calculation of the feedback signals at the sensors 17 and 18 is taken.

The outward signal from the control device 12 is used to modulate the ultrasonic frequency signal applied to the transducer 13. In this way, the instantaneous magnitude of the ultrasonic frequency signal is controlled in time to be proportional to the required radius of the workpiece so that the magnitude of the motion of the tool is independent of this signal. The contour of the workpiece will therefore be machined according to the contour signal.

주기 또는 다른 요구되는 변화내에서 대칭적인 변화가 될 수있다.It will be appreciated that the control device 12 can generate a modulating signal of varying magnitude within the rotation of the workpiece or between successive axial positions of the tool. Since there is a change in magnitude within the revolutions, this is in each half-cycle or in a different change in each half-cycle, or in fact the angle

It can be a symmetrical change within a period or other desired change.

In this way, machined workpieces such as pistons, bearings or piston rings in an internal combustor may be elliptical in cross section, additionally protrude along the axis length and shape of the cross section of the ellipse or other desired cross section. It can be produced as pointed or popped and pointed.

In addition, it is possible to machine with a tool to provide a contour on a surface located generally perpendicular to the axis of rotation of the workpiece, wherein each point of the surface is the required axial distance from the reference plane.

Continuous piezoelectric crystals can be supplied to amplify vibrations, and additionally or alternatively, waveguides can be provided between piezoelectric crystals or between crystals and tools to amplify vibrations.

As shown in the figure, although the control device 12 applies the external signal to the ultrasonic signal before the external signal is applied to the transducer 13, the control device 12 is external to the second transducer of the tool holder 14. It can be seen that the signal can be applied.

The tool holder can be made with very low weight and inertia and is coupled very close to the transducer 13. In this respect, it is possible to rotate the workpiece at a high speed, for example to produce numerous accurate changes in the radial position of the tool, precisely within revolutions, for example, at more than 3,000 revolutions per minute. For example, the tool can vibrate above 10,000 Hz with a movement of up to 0.1 mm. This allows for exceptionally high production rates while maintaining size accuracy.

In addition, the general benefits of ultrasonic machining are obtained. They include a reduction in tool force, which extends tool life and improves surface finish.

In FIG. 1 the tool is shown to be applied to the workpiece in the radial direction. However, as shown in FIG. 2, the toolholder can be applied to the workpiece with an angle in the radial direction. It has been found that this can be an improved cutting angle that requires less power in cuttings of the same depth and reduces frictional heat and piece-like work with vibrations induced on the cleaved surface above the tool edge.

It will be appreciated that the toolholder 14 will be arranged to operate independently of the ultrasonic device described above. This allows the toolholder 14 to be transported to the starting position and can also be used to route the tool position during machining.

The application of the ultrasonic signal brings the above benefits, but the presence of this signal is not absolute. Referring next to FIG. 3, parts common to FIGS. 3, 1 and 2 are given the same numerals and will not be described in detail. In this embodiment, the control device 12 generates various output signals as described in FIGS. 1 and 2. This signal is applied directly to the piezoelectric transducer 20 which performs linear motion in accordance with the output signal. This action is transferred to the tool 15 to cause the tool 15 to be operated in accordance with the output signal.

The piezoelectric transducer 20 may be replaced by any other transducer capable of converting an electrical output signal with a high speed corresponding high speed mechanical action that allows machining of the workpiece at high speed. Two implementations of an example of such an optional transducer are shown in FIGS. 4-6.

Referring first to FIG. 4, the first converter is a direct current linear motor comprising a U-shaped stationary core 25, generally having a U-shaped partial cylindrical rim for a common axis. The fixed paper coil 26 is wound around each of these rims. The rod-shaped floating permanent magnets 28 were coaxially located between the partially cylindrical U-rims. The extension 29 of the rod-shaped element 28 is supported in a bearing which may be a magnetic bearing or an air bearing formed from a pair of diaphragms 30. The tool 31 is supported at the extending end of the rod away from the stator coils 26.

This DC linear motor assembly is contained in a case 32 which carries a tool slide 33 and an electric motor (not shown) that move through the lead screw 34. The direct current linear motor is coupled so that the flexible rod-shaped permanent magnet 28 extends in the normal direction of the rotational axis 34 of the work piece 35 and is shown here as the phytonone of the internal combustion machine.

The slide 33 is arranged to be moved parallel to the axis of rotation 34 of the workpiece. In use the stator coils are connected to the control shown in FIG. 3 provided with feedback by a sensor of the kind shown in FIG. The workpiece 35 is rotated and the lead screw 34 is rotated to feed the tool 31 at a constant speed in the axial direction along the surface of the workpiece 35. The signals transmitted from the control device to the stator coils 26 cause the rod-shaped permanent magnet element 28 to be moved to a position according to the signal applied in the bearing, so that the tool 31 is machined to the required contour of the workpiece. Is moved to the required radial position momentarily. Less inertia and greater acceleration, the greater the force of this DC motor, allows the workpiece to be processed at high speeds by rotating the workpiece and changing the position of the tool several times.

The diaphragm 30 provides a tool position device in which the tool 31 tends to return to the reference position when there is no position signal.

One form of such a device is shown in detail in FIG. The device comprises a cylindrical housing 45 provided with an end clamp 46 which tightens each outer rim of the steel diaphragm 30, so that the diaphragms 30 are located on each side perpendicular to the housing axis. do. The tool holder in the form of an elongated bar 47 is connected to the diaphragm 30 and is arranged in a tool holder shaft that is coaxial with the axis of the housing 45. One end of the tool holder 47 is provided with a tool coupler 49, and the other end is connected to a floating permanent magnet element 28.

The linear motor can also be provided in the housing 45 between the diaphragms 30. It includes a slider 51 holding a stator 50 and a tool holder 47 fixed to the housing. The tool position device need not be moved by the linear motors 18 and 19. For example, the stator 50 may be replaced with a solenoid of the toolholder 47 acting as an armature in axial position in accordance with a signal applied to the solenoid, and three, four or more diaphragms may be provided. None of the tool forces varying from 5 kg to 25 kg are transmitted to the linear motor. All these tool forces are absorbed into the diaphragm 30. This means that the linear motor does not have to be large enough to eliminate unwanted vibrations during the operation of the toolholder 47.

This relates to the diaphragm 30. Therefore, the inertia of the permanent magnet element 28 or the slider 51 can be kept to a minimum, thus increasing the response potential speed.

In addition, since the force for moving the tool holder 47 is applied magnetically, it can be seen that there is no friction force between the tool holder 47 and the tool holder driver which tends to slow down the response time of the tool actuator.

Another form of linear motor is shown in FIG. In this embodiment, the direct current linear motor includes a generally U-shaped stationary core 36 with stator coils 37 wound around each of the U-shaped rims. The moving element 38 of the plate-shaped permanent magnet extends to the base of U between the rims of the U-shaped core. This element 38 is carried by a plurality of flexible plates 39, which are at each end thereof, supported by the base 40 and located on faces perpendicular to the length of the element 38, and thus the element 38. ) Has a limited motion in its longitudinal direction and receives resilience from the plate 39 which tries to return the element 38 to the reference position. The tool holder 41 is coupled to one end of the permanent magnet element 38 to receive the tool 42. The flexible cover 43 extends around the linear motor to shield the motor from the first and metal pieces.

In use, the direct current linear motor of FIG. 6 is coupled to the slide in the same way as in the linear motor of FIG. The stator coil 37 is connected to the control device of FIG. 3 so that the machining of the workpiece (not shown) is controlled in the same way as the tool in the embodiment of FIG.

Claims (11)

In a machine tool for processing a workpiece to a non-uniform surface contour, the surface contour of the workpiece requires a machining movement of the tool by relatively rotating between the tool and the workpiece, so that the machine tool is machined from information supplied to the control device. A control device for generating an electrical output signal which is a function of the required non-uniform surface contour of the workpiece to be formed, a tool for transferring the tool according to the output signal, and a tool operator, the tool operator corresponding to the electrical output signal A transducer 13, 20, 26, 28, 50, 51 connected to the control device for direct conversion into linear motion, the tool 15, 31, 42 being connected directly to the transducer for linear motion as required. Machine tool characterized by processing the workpiece with non-uniform surface appearance. Machine tool according to claim 1, characterized in that an ultrasonic oscillation signal source (10) is provided which is applied to the tool to vibrate the tool during machining. 3. Machine tool according to claim 2, characterized in that an ultrasonic oscillation signal is applied to an ultrasonic transducer (13; 20) whose output vibrates the tool. 4. Machine tool according to claim 3, characterized in that the ultrasonic transducer (13) also forms a transducer connected to the output of the control device (12), the electrical output signal from the control device modulating the ultrasonic vibration of the tool. Machine tool according to claim 1, characterized in that the transducer is a piezoelectric transducer which receives an electrical output signal and converts the signal into a mechanical motion applied to the tool (15). Machine tool as claimed in claim 1, characterized in that the transducer is an electromagnetic transducer (26, 28; 37, 38; 50, 51) which changes the linear position of the elements (28; 38; 57) in accordance with the electrical output signal. . 7. The transducer according to claim 6, wherein the transducers 26, 28; 37, 38; 50, 51 comprise a direct current linear vibrator, wherein the linear position of the floating permanent magnet elements 28; 38; 51 is from the control device. Machine tool characterized in that it is determined by a magnetic window generated in the stator coils (26; 37; 50) of the linear motor by the electrical output signal of the motor. 8. Tool according to any one of the preceding claims, wherein tool positioning means (30; 39) are provided for applying a force to the tools (31; 42) to keep the tool in the reference position. Machine tool characterized by moving from said reference position to a required position for machining a non-uniform surface contour. 9. The tool according to claim 8, wherein the tool is movable with the elongate element 29, the tool positioning means being located in each divided plane perpendicular to the axis of the elongate element and the axis of the elongate element coaxial with the axis of the diaphragm 30. A machine tool comprising two diaphragms connected to the elongate element. 9. A machine tool as claimed in claim 8, wherein the tool positioning means comprises at least one gas bearing. 9. The tool (42) according to claim 8, wherein the tool (42) is fluid with the elongated element (38), and the tool positioning means are located on each face perpendicular to the longitudinal direction of the elongated element and between the elongated element and the base (40). Machine tool characterized in that it comprises a plurality of flexible plates (39) connected.

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