KR20040097421A - Working force controllable processing device - Google Patents

Abstract

PURPOSE: A working force controllable processing device is provided to improve surface roughness and processing precision by uniformly keeping the working force between a tool and a workpiece. CONSTITUTION: A working force controllable processing device is composed of a frame(50), a tool(10) fixed detachably to a tool jig(80) mounted to a tool feed unit(70) and processing a workpiece, a sensor(20) having a load cell, an actuator(30) mounted to the frame and moving the tool forward and backward toward the workpiece, and a control unit(90). The sensor is mounted to the rear of the tool, and detects working force between the tool and the workpiece. The control unit compares the detected working force with setting working force, and controls the actuator to apply pressure to the tool. A tool guide rail(40) is mounted on the frame, and has an air slide for guiding the motion of the tool. The tool feed unit is mounted slidably to the tool guide rail so that the tool slides on the frame.

Description

WORKING FORCE CONTROLLABLE PROCESSING DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining force controlled machining apparatus for controlling machining force between a tool and a workpiece to a predetermined value in operations such as polishing, cutting, polishing, and the like.

Recently, high-speed, high-precision processing of products is increasingly required in order to maintain uniform product performance and processing accuracy in a short process time. In particular, in the case of post-treatment such as polishing, the value of the product is determined by the degree of processing as a final step for product completion. However, the variation in the processing force generated between the tools and the workpiece in the same or opposite directions are often in the high frequency band, which greatly affects the degree of surface treatment of the workpiece. That is, when the machining force increases during machining (particularly in the case of cutting machining), the unit cutting amount of the workpiece increases, and when the machining force decreases, the unit cutting amount also decreases, thereby preventing machining of the workpiece into the desired shape. . Therefore, the machining force between the tool and the workpiece must be kept constant in order for the machining conditions to be uniform during processing.

16 creates a pneumatic pressure (functioning as an air cushion) in the internal space 140a of the tool holder 140 holding the tool 110 to mitigate the vibration of the tool during machining, and the position of the internal space 140a. The processing apparatus which improves the processing precision of a to-be-processed object by controlling the position of the tool 110 by the sensor 120 is shown. The conventional processing apparatus shown in FIG. 16 includes a pneumatic machine 130 for forming pressure in the internal space 140a of the tool holder 140 through the pneumatic inlet port 150, and the tool 110 in the tool holder 140. According to the position sensor 120 for detecting the position of the tool and the position of the tool 110 measured by the position sensor 120 (depth (h) of the internal space 140a in the tool holder 140) ( The controller 130 is configured to control the pressure of the internal space 140a of the tool holder 140 by controlling the 130. An air outlet 170 is formed on the inner wall of the tool holder 140 to form an air flow. The depth h of the internal space 140a between the tool 110 and the tool holder 140 is detected by the position sensor 120 installed on the inner wall of the internal space 140a. Based on the depth h measured by the position sensor 120 according to the change of the profile of the machining surface, the controller 160 controls the pneumatic pressure 130 to control the depth h of the internal space 140a of the tool holder. do.

In such a conventional processing apparatus, the pneumatic pressure of the internal space 140a is determined by the amount of air drawn in from the pneumatic compressor 130 and the amount of air discharged to the discharge port 170, so that the pneumatic pressure eliminates vibration of the tool 110. It just acts as an air spring. Although the damping material formed of porous rubber is filled in the inner space 140a to further remove the vibration of the tool 110, this is merely passive control of the vibration. As described above, in the configuration of removing vibration of the tool by pneumatic pressure, it is difficult to attach the tool to the jig and there is a difficulty in jig design. Pneumatic pressure is slow in response to the characteristics of the pneumatic pressure, so it is possible to remove the variation in the machining force when the variation in the machining force is in the low frequency band, but it is difficult to eliminate the variation in the machining force in the high frequency band. In addition, since the apparatus measures and controls the depth h of the internal space 140a, it is difficult to immediately control the profile of the machining surface when the machining surface changes according to the cutting amount in the case of cutting. Therefore, the conventional processing apparatus does not react sensitively to the shape change of the workpiece, and thus the processing precision, the surface roughness, the homogeneity of the product, and the like decrease.

It is an object of the present invention to provide a machining force controlled processing apparatus for maintaining a constant machining force between a tool and a workpiece in order to maintain uniform product performance and machining accuracy.

It is another object of the present invention to provide a machining force controlled machining apparatus which eliminates the variation in machining force occurring between the tool and the workpiece in the high frequency band, thereby improving machining precision and surface roughness.

It is another object of the present invention to provide a machining force controlled machining apparatus that actively controls the machining force generated between the tool and the workpiece.

1 is a perspective view of a processing force controlled machining apparatus according to the present invention.

FIG. 2 is a plan view of the processing force controlled machining device shown in FIG.

3 is a side view of the machining force controlled processing apparatus shown in FIG.

Figure 4 is a perspective view of a height adjusting jig for adjusting the height of the actuator of the processing apparatus according to the present invention.

5 is a block diagram of a processing force control processing apparatus according to the present invention.

6 is a configuration diagram of a processing force control unit of the processing force control processing apparatus according to the present invention.

7a to 7d is a machining process diagram for processing the plane of the workpiece with a machining force controlled machining apparatus according to the present invention.

8a to 8d is a machining process diagram for processing the curved surface of the workpiece with a machining force controlled processing apparatus according to the present invention.

9 to 11 are the results of experiments in the variation of the machining force between the workpiece and the tool according to the machining time, and for the same machining conditions, FIG. Fig. 10 and Fig. 11 are graphs showing the results of the case where the processing force is kept constant and the step shape is changed by using the processing force controlled processing apparatus of the present invention, respectively.

12 and 13 are a perspective view and a side view of a processing force controlled machining apparatus according to another embodiment of the present invention.

14 and 15 are a perspective view and a plan view of a processing force controlled machining apparatus according to another embodiment of the present invention.

Fig. 16 is a schematic sectional view of a conventional machining force controlled processing device using pneumatic.

<Explanation of symbols for the main parts of the drawings>

10, 110: tool

20: load cell

30: Actuator

40: tool guide rail

50: frame

60, 160: control unit

61: computer

62: DSP board

63: load cell amplifier

64: voice coil linear motor amplifier

70: tool feed

80: tool jig

90: actuator height adjusting device

91a, 91b: fixed member

92a, 92b: movable member

93a, 93b: feed screw

94a, 94b: sliding member

100, 105: Workpiece

120: position sensor

130: pneumatic

140: tool holder

150: intake vent

170: outlet

One aspect of the present invention for achieving the above object of the present invention is a frame, a tool for processing the workpiece, a sensor mounted on the rear end of the tool for sensing the machining force between the tool and the workpiece; And an actuator mounted on the frame to move the tool back and forth in the direction of the workpiece, and a controller to control the actuator to press the tool such that the machining force detected from the sensor becomes a predetermined machining force. It relates to a processing apparatus.

The processing apparatus may further include a tool guide part mounted on the frame to guide the tool in the forward and backward directions. The tool guide may comprise an air slide. The sensor may be arranged between the tool and the actuator in the forward and backward direction of the tool, in particular coaxial with them. The sensor may include a load cell. The tool guide may include a tool jig, and the tool may be detachably mounted to the tool jig.

The processing apparatus of the present invention may further include a height adjusting device of the actuator. The frame may comprise a carbon fiber composite material, in particular an epoxy resin reinforced carbon fiber.

The actuator may comprise a voice coil linear motor.

The processing device may be detachably mounted to the spindle or feed table of the machine tool.

Another aspect of the present invention relates to a machine tool in which the above-described processing apparatus is mounted on a spindle or feeder.

1 to 3 show a perspective view, a plan view and a side view of a processing force controlled machining apparatus according to the present invention. In the processing apparatus of the present invention, a tool guide rail 40 is formed on the frame 50, and the actuator 30 is mounted. The tool 10 is detachably fixed to the tool jig 80 mounted on the tool feeder 70. The tool feeder 70 is slidably mounted on the tool guide rail 40 formed in the frame 50 so that the tool 10 is slidable on the frame 50. The lower end of the tool jig 80 is connected to the load cell 20 as a sensor for measuring the machining force (or working pressure) between the tool 10 and the workpiece 100 (shown in FIG. 10A) behind the tool. It is. An actuator 30 is connected to the other end of the load cell 20 connected to the tool 10 to advance and advance the tool 10 through the load cell 20.

The tool guide rail 40 and the tool feeder 70 perform a feed using a ball screw or the like. However, in this case, since the frictional force acts on the conveying part, it is difficult to accurately measure the machining force. Therefore, an air slide is preferably used. Although the AC servo motor may be used as the actuator 30, it is preferable to use a voice coil linear motor having a fast response, a high resolution, and a suitable value for performance in order to cope with the change in the processing pressure of the high frequency band. In addition, the frame 50 is preferably made of a carbon fiber composite material, more preferably an epoxy resin-reinforced carbon fiber, which is excellent in specific strength, specific rigidity, breaking strength, light weight, and has good damping characteristics against vibration. The frame 50 may be detachably mounted to a main shaft or a conveyer of a machine tool. In this embodiment, the position fixing hole 51 is formed in the frame 50 for this purpose, but the frame 50 may be mounted on the main shaft or the feed table of the machine tool by various other methods.

5 and 6 illustrate an example of the overall configuration diagram and the process of the processing force control of the processing force control processing apparatus according to the present invention. As shown in Fig. 5, when the processing apparatus of the present invention processes the workpiece 100, the processing force generated between them is sensed in the load cell 20. The sensed cutting force signal is input to the controller 60. The sensed processing force signal input to the controller 60 is amplified by the load cell amplifier 63 and transferred to the computer 61 and the DSP board 62 mounted thereon. The computer 61 and the DSP board 62 compare the sensed machining force with a predetermined reference machining force, and the actuator 30 controls the machining force to the reference machining force by pressing or depressurizing the tool 10 (Fig. 6). The signal processed by the computer 61 and the DSP board 62 is output to the voice coil linear motor which is the actuator 30 via the voice coil linear motor amplifier 64.

Next, the process of processing the plane of the workpiece will be described with reference to Figs. 7A to 7D. Before the machining is started, the workpiece to be processed is measured, the desired machining force is input and the tool and the workpiece are rotated. When work preparation is complete, a constant voltage is applied to the actuator 30 to position the tool 10 at the reference line as shown in FIG. 7A. Then, as shown in Fig. 7B, the processing apparatus of the present invention is transferred to the workpiece 100 to be processed to bring the tool 10 into contact with the workpiece 100. Whether the contact is detected when the input signal set from the load cell 20 is detected that the contact is made and stops the transfer of the processing device. After contact between the tool 10 and the workpiece 100, the actuator 30 is advanced in the direction of the workpiece 100 until the desired machining force is reached. When the desired machining force is achieved, the workpiece is processed by advancing the actuator 30 back and forth while maintaining a constant working pressure as shown in FIG. 7C. When the processing is completed, the processing apparatus of the present invention is retracted as shown in Fig. 7D.

Since the machining device of the present invention can be easily tilted between the tool and the workpiece, it is possible to process spherical and aspherical surfaces, and it is possible to calculate the amount of processing since the machining force can be kept constant during the machining, thereby modifying the shape and surface of a certain shape. You can improve the degree. Such a processing device may also be effective for machining drills, boring, and the like that require tilting. In the case of the curved surface processing of the workpiece, the tilting angle of the tool according to the machining position is determined by measuring the shape of the spherical and aspherical surfaces of the workpiece 100 before machining, and the machining is performed by the process as shown in FIGS. 8A to 8D. Is done.

In the above description, the processing apparatus is moved forward and backward and / or tilted with respect to the workpiece 100, but the present invention is not limited thereto, and the workpiece 100 may be moved forward and backward and / or tilted with respect to the processing apparatus.

9 to 11 are the results of experiments in the variation of the machining force between the workpiece and the tool according to the machining time. The cutting force measured at a cutting frequency of 200 Hz was outputted when the workpiece rotated at 50 rpm was cut at a target machining force set at 100 gf using a tool rotating at 1000 rpm. Fig. 9 shows results of a conventional processing apparatus, and Figs. 10 and 11 show a case where the processing force is kept constant using the processing force controlled processing apparatus of the present invention (Fig. 10) and a step change (Fig. 10). 11) is the result. As can be seen from the results, it can be seen that the processing force controlled processing apparatus of the present invention is obtained with almost constant processing force without variation.

12 and 13 show, as another embodiment of the present invention, the load cell 20 and the actuator 30 disposed on the same central axis at the rear end in the longitudinal direction of the tool 10. In this embodiment, since the tool 10, the load cell 20 and the actuator 30 are on a common axis, the point where the processing force occurs and the point for measuring the processing force are on the same line. Therefore, in the present embodiment, since the generation of the moment due to the difference between the point where the machining force is generated and the point for measuring it is eliminated, accurate measurement of the machining force and the acceleration and deceleration of the tool is achieved.

12 and 13 may be configured by replacing the tool of the processing device of FIGS. 1 to 3 with a tool that can be coupled to the load cell 20, and adjusting the height of the load cell 20 and the actuator 30. . In addition, in the machining force controlled machining apparatus of FIGS. 7 to 9, when the tool is replaced with another type of tool, for example, a tool having a different diameter, the load cell 20 and the actuator 30 may be moved to the central axis of the tool 10. Need to match. This is achieved by adjusting the height of the load cell 20 and the actuator 30 by an actuator height adjusting device 90 mounted between the actuator 30 and the frame 50. Fig. 4 is an actuator height adjusting device 90, which slides on the inclined surfaces of the pair of fixing members 91a and 91b in the shape of wedges arranged side by side on the frame 50 and the fixing members 91a and 91b. A pair of wedge-shaped movable members 92a and 92b that are possibly mounted. These fixing members 91a and 91b and movable members 92a and 92b are mounted on the sliding members 94a and 94b on which the fixing members 91a and 91b are slidably mounted in the vertical direction, as shown in FIG. Connected by the mounted feed screws 93a and 93b, the actuators 92a and 92b move up or down along the inclined surfaces of the fixing members 91a and 91b as the feed screws 93a and 93b rotate. 30) height is adjusted.

As another embodiment of the present invention, as shown in Figs. 14 and 15, the load cell 20 and the actuator 30 may be arranged side by side at the lower end of the tool jig 80 to the rear of the tool.

By the above-described configuration, the machining force controlled processing device of the present invention can maintain the machining force between the tool and the workpiece to be constant, thereby improving machining precision and surface roughness, and maintaining uniform product performance and machining accuracy. The machining apparatus of the present invention does not need to control the position of the tool separately according to the profile of the workpiece because it measures and controls the machining force between the tool and the workpiece. In addition, the processing apparatus of the present invention can be tilted to allow the processing of spherical and aspherical surfaces, and may also be effective in the machining of drilling, boring, and the like, which require tilting.

Claims (8)

Frame, Tools for processing workpieces, A sensor mounted to a rear end of the tool to sense a processing force between the tool and the workpiece; An actuator mounted on the frame to move the tool back and forth in the direction of the workpiece; And a controller for controlling the actuator to press the tool such that the machining force sensed by the sensor becomes a predetermined machining force. The apparatus of claim 1, further comprising a tool guide mounted on the frame to guide a tool in the forward and backward directions, wherein the tool guide comprises an air slide. The actuator according to claim 1 or 2, wherein the sensor further comprises a height adjusting device of the actuator arranged coaxially between the tool and the actuator in the forward and backward direction of the tool and for arranging the actuator in a line with the tool. A processing force controlled processing device, characterized in that. The processing force controlled processing apparatus according to claim 1 or 2, wherein the sensor comprises a load cell. The processing force controlled processing apparatus according to claim 1 or 2, wherein the frame comprises a carbon fiber composite material. The processing force control processing apparatus according to claim 1 or 2, wherein the actuator comprises a voice coil linear motor. The processing force control processing apparatus according to claim 1 or 2, wherein the processing apparatus is detachably mounted to a main shaft or a feed table of the machine tool. Machine tool according to claim 1 or 2, wherein the machining device according to claim 1 is mounted on a spindle or feeder.