JP2011056605A - Stitching machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stitching machining method which achieves a conventionally impossible tool change during machining when performing machining of a roll die in a high-precision, three-dimensional fine shape over a large area or machining of a plane in a high-precision, three-dimensional fine shape over a large area, thereby enabling machining by connecting an already machined portion to an unmachined portion. <P>SOLUTION: In a process of replacing a worn or damaged tool when cutting a precise, three-dimensional, fine geometric pattern repeatedly on a surface of a workpiece using a machining measuring apparatus which integrally comprises an actuator driving the tool, a tool holder coupled with the actuator and holding the tool, a displacement sensor disposed coaxially with the actuator and measuring the displacement of the tool, and a force sensor measuring the force applied to the tool, the stitching machining method uses the machining measuring apparatus on which a replacing tool is attached as a displacement measurement probe to measure the shape of an already machined pattern by scanning, thereby accurately identifying the position of the replacing tool. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  In the present invention, when performing a precise three-dimensional fine roll mold processing or large flat area processing on the surface of a workpiece by cutting, in the case of tool replacement due to tool wear or breakage, the tip position of the replaced tool and The present invention relates to a stitching processing method of a three-dimensional fine shape that can be processed by connecting an already processed part and an unprocessed part without giving a positioning deviation from the rework point.

  Parts having a three-dimensional fine shape are often used in video equipment and information communication equipment. Among them, a three-dimensional fine shape having an optical function such as a microlens array can give the display device functions such as correction of light source intensity distribution and antireflection. As a three-dimensional fine shape creation technique, a processing method capable of creating a highly accurate shape over a large area is desirable.

  On the other hand, with the current ultra-precise cutting technology, machining with precision below the micro-order has become easy due to advances in precision motion control and precision machining tools. Typical machining is diamond cutting using an ultra-precision lathe, which uses a single crystal diamond cutting tool with a very sharp cutting edge to process a three-dimensional fine shape on the surface of the workpiece. Is the method. Diamond cutting has a good finish and features suitable for forming fine surface shapes. Among ultra-precision machining, a processing apparatus that can create a complicated three-dimensional fine shape over a large area by controlling a single crystal diamond cutting tool at high speed is used (for example, see Patent Document 1).

  However, in the cutting with a single crystal diamond cutting tool, the processing time is prolonged due to the increase in the area of the three-dimensional fine shape, so that the tool tip is easily worn. When tool wear occurs, the compressive residual stress during processing increases and the finished surface roughness deteriorates. Therefore, it is important to know the state of the tool being machined, and it is also required to detect the machining force generated between the tool and the workpiece in-process (see, for example, Patent Document 1).

  When tool wear is detected by the in-process detection of the processing force, the worn tool is replaced with a new tool in the conventional three-dimensional micromachining by cutting, and the already machined three-dimensional microshape is included. Re-surface the surface of the workpiece. At this time, the already processed three-dimensional fine shape is removed from the surface of the workpiece, the processing time becomes longer, and the processing efficiency deteriorates.

  In order to achieve high-efficiency machining of large-area three-dimensional fine-shaped roll molds with high precision and large-area flat surfaces, when a tool worn during machining is replaced, the surface of the workpiece is not resurfaced. There is a need for a method (stitching process) in which an already processed part and an unprocessed part are connected and processed. In the case of stitching, high-precision positioning between the tool tip and the rework point by tool change is an important issue.

JP 2009-142950 A

  When processing a highly accurate 3D micro-shaped roll mold over a large area, or when processing a highly accurate 3D micro-shaped plane over a large area, processing that was not possible before It is an object of the present invention to provide a stitching method capable of realizing a tool change in the middle and connecting an already processed part and an unprocessed part.

  According to the present invention, an actuator that drives a tool, a tool holder that is coupled to the actuator and holds the tool, a displacement sensor that is arranged coaxially with the actuator and that measures the displacement of the tool, and the tool When a precise three-dimensional fine pattern is repeatedly cut on the surface of a workpiece using a machining measuring device that is configured integrally with a force sensor that measures an applied force, the tool is worn due to wear or breakage of the tool. In the process of replacing the tool, the position of the replaced tool is accurately identified by scanning and measuring the shape of the already-processed pattern, using the processing measuring device with the replaced tool as a displacement measuring probe. Is obtained.

  According to the present invention, when a tool that has been worn or damaged is replaced and reworked during the processing of a three-dimensional fine shape roll mold or a three-dimensional fine shape plane, By using the three-dimensional fine shape of the part as a measurement standard, the positioning of the tool tip and the reworked point can be made to coincide with each other with high accuracy, and the already machined part and the unmachined part can be connected for machining. For this reason, it is possible to reduce a decrease in processing efficiency due to the resurfaced surface of the workpiece. Furthermore, by using the machining probe as a shape measuring probe, it is possible to evaluate the shape on the machine in a short time without removing the workpiece processed with the three-dimensional fine shape from the ultraprecision lathe.

It is the schematic which shows the positioning deviation of the tool front-end | tip position by a tool exchange, and the process origin of the stitching processing method of embodiment of this invention. It is the schematic which shows the three-dimensional fine shape measurement principle by the machined shape evaluation system of the stitching method of embodiment of this invention. It is a block diagram of the on-machine processing shape evaluation system of the stitching processing method of an embodiment of the invention. It is the schematic which shows the positioning method of the tool front-end | tip position and rework point by three-dimensional fine shape evaluation of the stitching processing method of embodiment of this invention. It is a graph showing the contact force (measurement force) when the processing shape surface and tool by the on-machine processing shape evaluation system of the stitching processing method of embodiment of this invention contact. It is a graph showing the shape evaluation displacement resolution of the machining shape evaluation system on a machine of the stitching processing method of embodiment of this invention. It is a graph showing the result of having measured the three-dimensional fine shape by the on-machine processing shape evaluation system of the stitching processing method of embodiment of this invention. It is a surface view of the workpiece which shows the result of having connected and processed a three-dimensional fine shape to an already processed part when there is a tool tip positioning deviation after tool exchange. In the stitching processing method according to the embodiment of the present invention, after aligning the tool tip and the rework point with high accuracy using the three-dimensional fine shape of the already machined part as a measurement standard, It is a surface view of the processed material which shows the result of having connected and processed the part.

Hereinafter, a stitching method according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows the positional deviation between the tool tip position and the machining origin due to tool replacement. The three-dimensional fine shape 102 is processed on the surface of the workpiece 101 by controlling the tool 103 at high speed with an axial pitch 107 and a circumferential pitch 108. However, when the tool 103 that has been worn or damaged during machining is replaced and reworked, the tool tip center 111 changes to a new tool tip center 112 due to a difference in the height of the core of the tool 103 or a tool attachment deviation. The tool tip center 112 after the tool change has a deviation in two directions of an axial direction deviation 113 and a circumferential direction deviation 114 from the tool tip center 111 before the tool change. When the tool is changed, the processed three-dimensional fine shape 102 is used as a measurement reference, and the positioning of the tool tip and the rework point is made to coincide with each other with high accuracy, so that the three-dimensional fine shape 102 and the processed part 109 are not processed. Stitching that connects and processes the portion 110 is possible.

  FIG. 2 shows the measurement principle of a three-dimensional fine shape by the machined shape evaluation system. First, the workpiece 101 processed with the three-dimensional fine shape 102 is attached to the main shaft, and the tool 103 is slightly vibrated using the PZT actuator 106 of the tool control mechanism 120 used for processing the three-dimensional fine shape 102. Approach the workpiece 101. The contact between the tool 103 and the surface of the workpiece 101 in the elastic deformation region is detected by a force sensor 104 incorporated in the tool control mechanism 120, and the position of the tool 103 is accelerated by the PID controller 170 so that the contact force is constant. While controlling, the spindle to which the workpiece 101 is attached is rotated at a constant speed. At this time, the motion trajectory of the tool 103 becomes the shape measurement result, and the trajectory is measured by the displacement sensor 105 mounted on the tool control mechanism 120. A rotary encoder is attached to the lathe spindle, and the output of the displacement sensor 105 is synchronized with the rotary encoder pulse. By detecting the position using the rotary encoder pulse and using the machining probe as a shape measurement probe, the machining point and the shape measurement point can be matched.

  FIG. 3 shows a block diagram of the on-machine machining shape evaluation system. The on-machine machining shape evaluation system includes a tool control mechanism 120 having a force sensor 104, a PID control unit 210 that controls the position of the tool 103 so that the contact force is constant, and a computer that records the output signal of the displacement sensor 105. 200. In order to detect contact between the three-dimensional fine shape 102 and the tool 103 with high sensitivity, a filtering method using a lock-in amplifier 150 is used. In order to detect a specific frequency component with high sensitivity, it is necessary to input a reference signal to the lock-in amplifier 150. The sinusoidal voltage signal generated by the function generator 180 is applied to the PZT actuator 106 of the tool control mechanism 120 via the PZT drive amplifier 190 to cause the tool 103 to vibrate slightly. The force sensor 104 attached directly behind the tool 103 detects the vibration of the tool 103 and amplifies it by the charge amplifier 140. By branching the sinusoidal signal generated by the function generator 180 and inputting a reference signal to the PZT actuator 106 and the lock-in amplifier 150, the output signal output from the force sensor 104 and the reference signal detect the same frequency. In order to detect only the tool driving frequency component of the contact force when the three-dimensional fine shape 102 and the tool 103 are in contact with each other with high sensitivity and to realize shape measurement with a constant low measurement force, the control by the PID controller 170 is performed. Do.

  Next, a method for positioning the tool tip position and the rework point at the time of tool change will be described. FIG. 4 shows a method of matching the positioning of the tool tip rework point with high accuracy using the machined shape as a measurement reference when changing the tool. First, the axial shape of the three-dimensional fine shape 102 is measured by a machined shape evaluation system. While controlling the position of the tool 103 so that the three-dimensional fine shape 102 and the tool 103 always have a constant low measuring force, the tool 103 is scanned in the axial direction using an X slide of an ultra-precision lathe. At this time, the motion trajectory of the tool 103 becomes the shape measurement result in the axial direction of the three-dimensional fine shape 102. The movement trajectory in the axial direction is synchronized with the pulse of the linear encoder attached to the X axis (axial direction) of the ultra-precision lathe, and the position of the axial center of the three-dimensional fine shape 102 is detected with a resolution of 10 nm. be able to.

  Similarly, the spindle to which the workpiece 101 is attached is rotated at a constant speed while controlling the position of the tool 103 so that the three-dimensional fine shape 102 and the tool 103 always have a constant low measuring force. The circumferential motion trajectory of the tool 103 is the result of measuring the circumferential shape of the three-dimensional fine shape 102, and the motion trajectory is also synchronized with the pulse of the rotary encoder attached to the ultraprecision lathe spindle. The position of the center of the dimensional fine shape 102 in the circumferential direction can be detected with a resolution of 0.001 °.

  By driving the PZT actuator 106 of the tool control mechanism 120, the tool 103 is brought close to the workpiece surface 101 while slightly vibrating. FIG. 5 shows the contact force detected by using the force sensor 104 attached just behind the tool 103 for contact between the tool 103 and the surface of the workpiece 101.

  In order to evaluate the shape evaluation displacement resolution of the machining shape evaluation system on the machine, a step of 30 nm is given to the surface of the workpiece 101 in the cutting direction using the Z slide of the ultra-precision lathe, and the followability of the tool 103 by PID control is given. The confirmed result is shown in FIG. The stability of the displacement sensor when the surface of the workpiece 101 is in contact with the tool 103 is about 30 nm.

  Using a tool 103 having a corner radius R of 0.2 mm, a three-dimensional fine shape machining having a depth of 5.2 μm and a pitch of 200 μm was performed on the surface of the workpiece 101. FIG. 7 shows the result of measuring the shape in the axial direction and the shape in the circumferential direction of the three-dimensional fine shape 102 by the machined shape evaluation system. Thereby, the center 116 of the axial movement locus of the tool 103 and the center 117 of the circumferential movement locus of the tool 103 can be detected with high accuracy.

  When the tool 103 worn during machining is replaced and reworked, the tool exchanged with the machining center position of the three-dimensional fine shape 102 of the already machined part due to the difference in the height of the core of the tool 103 or the tool mounting deviation. There is a positioning deviation between the center of the tip and the center. In order to confirm the influence of the deviation between the processing center position and the tool tip center position after the tool change when changing the tool in the processing of the three-dimensional fine shape, the tool 103 is replaced, and then the three-dimensional fine shape 102 is changed to the already processed part. Connect to and process. The result is shown in FIG. Due to the influence of the tool tip positioning deviation due to the tool change, it is impossible to connect to the three-dimensional fine shape 102 of the already processed part.

  The machined shape evaluation system measures the axial shape and circumferential shape of the three-dimensional fine shape 102, and uses the three-dimensional fine shape 102 of the already machined part as a measurement standard to measure the tool tip and rework point. FIG. 9 shows a result obtained by processing the three-dimensional fine shapes 102 by matching the positioning of the three-dimensional fine shapes 102 with high accuracy. As a result, it is possible to perform a stitching process in which the processed part and the non-processed part are connected and processed without giving a positioning deviation between the tip position of the tool 103 and the rework point due to tool replacement.

DESCRIPTION OF SYMBOLS 101 Workpiece | work 102 Three-dimensional fine shape 103 Tool 104 Force sensor 105 Displacement sensor 106 PZT actuator 107 Axial pitch 108 (Three-dimensional fine shape) Circumferential pitch 109 (Three-dimensional fine shape) Ready part 110 Unprocessed part (three-dimensional fine shape) 111 Tool tip center 112 (before tool change) Tool tip center 113 (after tool change) Axial deviation 114 (due to tool change) Circle 114 (due to tool change) Circumferential deviation 115 Center of axial direction of three-dimensional fine shape 116 Center of axial movement locus of (tool) 117 Center of circumferential direction of three-dimensional fine shape 118 Center of circumferential movement locus of (tool) 120 Tool control mechanism 130 Displacement sensor amplifier 140 Charge amplifier 150 Lock-in amplifier 160 Reference signal 170 PID control 180 Function Zee Nereta 190 PZT drive amplifier 200 computer (A / D converter)
210 PID controller

Claims (1)

An actuator that drives a tool, a tool holder that is coupled to the actuator and holds the tool, a displacement sensor that is arranged coaxially with the actuator and that measures the displacement of the tool, and that measures the force applied to the tool In the process of exchanging the tool due to wear or damage of the tool when repeatedly cutting a precise three-dimensional fine shape pattern on the surface of the workpiece using a processing measurement device configured integrally with a force sensor that performs Stitch characterized in that the position of the replaced tool is accurately identified by scanning and measuring the shape of the already-processed pattern, using the processing measuring device with the replaced tool as a displacement measuring probe. Processing method.