JPH0526248U - Cutting equipment - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] In the field of ultra-precision cutting, to prevent damage to the force sensor that detects the cutting state and shape accuracy during processing in real time. [Structure] A force sensor 4 for detecting a processing reaction force during cutting is attached to the tool rest 3. A limiting member 32 is fixed above and below the force sensor 4 with a slight gap G in contact therewith at the base. The voltage applied to the piezo element P is changed so that the force sensor 4 is not deformed beyond the deformation range by inserting the piezo element P into the restriction member 32 and the force sensor 4 is deformed. The gap G is finely adjusted to limit the amount of deformation.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a cutting device using a thin metal cylindrical member used in an image forming apparatus as a member to be cut.

[0002]

[Prior Art]

 For example, in the field of ultra-precision cutting of photoconductor drums and magnetic disk substrates, mirror finishing is usually performed. When inspecting these products, not only dimensional accuracy and shape accuracy but also whether or not the surface is a mirror surface is important, and in many cases fine scratches with a width of about 10 μm called scratches are not allowed.

Regarding the inspection of the surface state, at present, the operator visually inspects after processing. This method requires the skill of the worker and poses a problem in promoting the automation of processing.

Further, the following research has been conducted on the inspection of the surface state.

1) A technique for measuring the roughness of a machined surface by scattered light obtained by irradiating the surface of a workpiece with laser light (Kenji Morita, Yoichi Kawakubo: Mirror surface machining using diffracted light Sano in-process measurement, Journal of Precision Engineering, 54, 4 (1988), 642-646).

2) A technique for quantitatively measuring and evaluating fine scratches on a processed surface by scattered light obtained by shining a laser beam on the surface of a workpiece (Takashi Miyoshi, Jun Kangei, Katsumasa Saito: using scattering theory) Study on measurement and evaluation of small scratches (1st report), Journal of Precision Engineering, 54, 6 (1988), 1095-1100).

3) Non-contact measurement of surface roughness using the critical angle method using laser light (Tsuguo Kono: Outline of in-process measurement processing control technology, Joint presentation by Precision Engineering Society, Industry-Academia Cooperative Research Cooperation Subcommittee) Meeting symposium text, 1990, 1-5).

Further, the following research has been conducted on monitoring the processing state by paying attention to vibration during processing, AE signal, heat flow and the like.

4) Technology for recognizing phenomena such as chip entanglement during machining by focusing on heat flux (Hidenori Shinno, M. Rahman, Chikaro Inaba: Recognition of machining environment based on heat flux measurement-total Validity evaluation of measurement results-Proceedings of the Japan Society for Precision Engineering Autumn Meeting, 1990, 583-584).

5) Technology for recognizing the wear state of tools using ultrasonic signals (Shuzo Ito, Fujio Shirasawa, Chikaro Inaba, Kei Ito: Tool wear state recognition using ultrasonic in-process sensors, Japan Society for Precision Engineering Autumn Meeting Academic Proceedings, 1990, 585-586).

In the measurement of shape accuracy, an attempt has been made to realize high-precision processing by measuring the shape of a processed workpiece and feeding back the depth of cut (Tsuguo Kono: In-process measurement processing). Outline of control technology, symposium text of the presentation meeting of the precision engineering society, industry-academia cooperative research cooperation subcommittee, 1990, 1-5.

[0012]

[Problems to be solved by the device]

 Among these conventional techniques, those that monitor vibrations and AE signals during machining are mainly intended to detect wear and breakage of tools. In addition, it is considered difficult for a device that monitors the heat flow during processing to detect a high-speed phenomenon because the heat information generally has a time delay. In addition, these technologies are targeted for general precision processing on the order of μm, and there is no case where they are applied to ultra-precision cutting processing.

Further, the optical measuring method using laser light has the following drawbacks.

When optically measuring the shape and roughness of the surface using laser light, the cutting edge of the cutting tool and the point measured by the sensor are made to be the same due to spatial restrictions. It's difficult. Therefore, the information detected by the sensor is not exactly the information of the processing point, but has a slight time difference.

In addition, cutting fluid is often used in actual machining, and its influence also becomes a problem in optical measurement methods, so it is difficult to apply it to actual production as in-process measurement. . Therefore, in the optical method, the measurement is performed after the processing, and the inspection takes time.

Therefore, we paid attention to the processing reaction force as a parameter measured during processing. The processing reaction force is a physical quantity generated at the processing point itself, and if the surface shape or state during processing changes, the processing reaction force is also considered to change with the surface shape or state. is there.

A force sensor using a strain gauge is used as the detection means for detecting the processing reaction force.

The force sensor is attached to the base of the tool shank supporting the cutting tool, and the cutting resistance received by the tool is converted into a signal of an electric processing reaction force of the strain gauge provided on the base of the tool shank to process the machining state. Can be displayed as a mode pattern waveform.

Therefore, by feeding back the information obtained from the mode pattern signal, it becomes possible to automatically correct the machining state of the workpiece.

However, if the force sensor is subjected to an abnormally large cutting resistance, or if an external force exceeding the limit is applied due to a collision with another instrument, it is difficult to destroy and restore the force sensor. A protective device is required to prevent deformation beyond the range where the processing reaction force of the sensor is detected.

In general, as a protective device, a strong block member, which forms a slight gap with the outer wall of the tool rest by adjusting the screw of a bolt, is installed on the outer wall of the force sensor to receive a large external force. At this time, the deformation of the force sensor is prevented by the block member, but since the gap must be set with extremely high accuracy within the range of several microns to several tens of microns, adjustment of the bolt will increase the It was difficult to set the accuracy, and it was therefore difficult to ensure complete protection of the force sensor without requiring a great amount of adjustment time.

As a result of solving this problem and improving the present invention, the allowable deformation range of the force sensor is set with high accuracy, and as a result, measures are taken to prevent damage to the force sensor in advance. The purpose of the present invention is to provide a cutting machine capable of performing the above.

[0023]

[Means for Solving the Problems]

 The above-mentioned object is to detect the reaction force at the time of cutting on the tool post of the tool used for the cutting in the cutting device using the thin metal cylindrical member used for the image forming apparatus as the member to be cut. The present invention is achieved by a cutting machine characterized in that a force sensor is installed and the operating range of the force sensor is restricted by using a piezo element to prevent damage to the force sensor.

[0024]

【Example】

 An embodiment of the cutting apparatus of the present invention will be described below. FIG. 1 is a schematic view of a cutting device, and FIG. 2 is a diagram showing an output waveform of a processing reaction force during cutting.

The cutting apparatus of the present invention uses a metal thin-walled cylindrical member used in an image forming apparatus as a member to be cut, and is a metal thin-walled cylindrical member used in a copying machine or a laser beam printer. A lathe 2 for processing the photosensitive drum substrate 1 is provided with a tool rest 3. The tool rest 3 is equipped with a force sensor, that is, a force sensor 4 that uses a strain gauge that detects the processing reaction force during cutting. This force sensor 4 cuts from the tool A used for cutting. It constitutes a detection means for detecting the processing reaction force during processing.

The output signal obtained from the force sensor 4 is amplified by the dynamic strain gauge 5, converted into a digital signal by the AD converter 6, and taken into the computer 7. A memory and a disk device are connected to the computer 7 as a storage means 8, and a plurality of mode pattern signals categorized according to the processing surface state at the time of cutting stored in the memory 7 and the force sensor 4 are stored. The output signal obtained from the above is compared by the comparison means 9 to detect the state during cutting. The computer 7 creates a signal for controlling the machining after detection and sends a control signal to the NC device or the sequencer 10 for controlling the lathe 2 via a digital IO board / RS232C interface or the like.

The output signal obtained from the force sensor 4 may be filtered by a low-pass filter, a high-pass filter, a band-pass filter, etc., and then input to the AD converter 6, and these filter processes may be AD-converted. It may be performed by software after AD conversion by the device 6, so that noise can be removed.

For detecting the processing reaction force during cutting, for example, 1989 Precision Engineering Society Autumn Meeting Academic Lectures, pp. 111-112 “Trial of Monoblock Type Three-Component Force Detection Holder for Magnetic Disk Cutting” (Yotaro Hatamura, Adachi Mitsuaki) The tool-integrated machining reaction force detection holder described can be used. This sensor has the same size as a normal bite shank, is compact and has high rigidity. In fact, it has been recognized that when processing is performed using this sensor, a mirror surface can be formed and the shape accuracy is about the same as that of a normal shank.

As the dynamic strain gauge 5, for example, a DPM613B manufactured by Kyowa Denki Co., Ltd. is used as an AD converter, for example, an AD conversion board ADX-98E manufactured by Canopus Electronics Co., Ltd., and as an interface board, for example, Contec Co., Ltd. IO. The board PIO-24 / 24 (98) can be used as a computer, for example, PC-9801UV manufactured by NEC Corporation.

Next, an example of detecting a processing state during cutting using this cutting apparatus will be described. The workpiece was a thin-walled aluminum cylinder corresponding to the material A5805, and the photosensitive drum substrate 1 having a diameter of 60 mm and a thickness of 1 mm was used. The tool used was a natural single crystal diamond flat tool. The processing conditions were: spindle speed 6,000 rpm, feed 0.2 mm / rev, depth of cut 20 μm.

In the processing of the photoconductor drum substrate 1, surface defects are important as defects that occur during processing. Specifically, there are chatter vibrations, scratches, defects due to entanglement of cutting chips, and uncut parts. Conventionally, these defects were visually judged by humans after processing. It was found that these phenomena can be detected from the output signal by classifying the output signal pattern of the processing reaction force.

When the processing reaction force is detected, it is checked whether the force sensor 4 is operating normally. Specifically, the force sensor 4 used detects the force by converting it into strain with a strain gauge, so the dynamic strain gauge 5 balances the circuit before use, and the output signal after balance adjustment is set. If it is within the range, it is determined to be operating normally. If the circuit of the force sensor 4 has a failure such as a wire breakage, the output signal after the balance adjustment is out of the set range, and it can be seen that the operation is not normal.

FIG. 2 is a waveform of an output signal of a processing reaction force corresponding to a normal cutting state where a mirror surface having a surface state of about 0.2S to 0.3S is obtained. The processing reaction force is detected at the start of processing, and by paying attention to the rise of the output signal of this processing reaction force, the processing start is automatically determined. In addition, the output signal returns to almost zero level when the machining is completed, and by paying attention to the trailing edge of this output signal, the automatic completion of machining is determined.

FIG. 3 shows a detailed configuration of the tool rest 3, in which the tool A is attached to the force sensor 4 via a fixture 30 and the force sensor 4 is fixed to the tool rest 3. .

The force sensor 4 has a square hole 31B penetrating the middle portion of the square groove 31A provided on the upper bottom surface thereof, and the above-mentioned strain is formed on the upper and lower bottoms of the square hole 31B corresponding to the square groove 31A. Each gauge 31 is attached and attached.

The force sensor 4 detects the cutting resistance of the tool A received when the photosensitive drum substrate 1 is processed, as a tensile or compressive strain acting on the upper bottom surface of the square hole 31B, and detects the processing resistance. The force is output as the signal waveform described above.

On the upper and lower outer side surfaces of the force sensor 4, each limiting member 32 with a slight gap G is fixed in a state of being in contact with the base portion.

In the cutting apparatus of the present invention, each limiting member 32 has a piezo element P attached inside each square hole 32B that is connected to and penetrates the cut groove 32A, and is applied to the piezo element P. The gap G is adapted to be finely adjusted by the applied voltage.

Therefore, a static load is applied to the preliminary cutting tool, and the load on the cutting tool is gradually increased while detecting the output from the force sensor 4.

When the output from the force sensor 4 indicates a certain set value within the measurable limit value (for example, 50% to 70% of the limit strain amount), the force sensor 4 falls below the threshold value. Set the gap G so that it does not move. The gap G is set by changing the applied voltage to the piezo element P and increasing the load on the cutting tool, so that the deformation of the tool rest 31 is blocked by the restricting member 32 and the force sense is suppressed. This is performed by adjusting so that the output from the sensor 4 does not change beyond the set value.

If the machining state is normal and the cutting resistance received by the tool A is within the preset setting range, the elastic deformation of the force sensor 4 remains within the above-mentioned gap G, and thus The machining is continued without contacting each of the restriction members 32.

If a strong external force is applied to the force sensor 4 itself beyond the preset setting range, the cutting resistance received by the tool A becomes abnormal due to abnormal machining conditions or an accident occurs, and the force sensor 4 Is deformed and the gap G becomes 0, and the force sensor 4 contacts the limiting member 32. As a result, the force sensor 4 is prevented from being deformed by the limiting member 32, and the force sensor 4 distorts more than the set strain. Before the force sensor 4 receives an excessive external force that causes damage, the external force is removed and destruction is prevented.

Although this embodiment is a mechanism for preventing damage to the force sensor 4 in the main component force direction, it is easy to prevent damage in the same manner with respect to the feed force component and the back force component direction.

Further, with respect to the force sensor of the type using a strain gauge, it is easy to prevent damage by utilizing the present invention.

[0045]

[Effect of the device]

 The present invention makes it possible to properly prevent the tool-integrated force sensor from being damaged due to abnormal cutting or a predicted accident, and as a result, it is possible to always detect a machining reaction force and perform mirror finishing. A cutting machine that can be obtained is provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a cutting device.

FIG. 2 is a diagram showing an output waveform of a processing reaction force during cutting.

FIG. 3 is a detailed configuration diagram of a tool rest.

[Explanation of symbols]

 1 Photoconductor Drum Base 2 Lathe 3 Turret 3 Force Sensor 5 Dynamic Strain Meter 6 AD Converter 7 Computer 8 Storage Means 9 Comparing Means 10 NC Device or Sequencer 11 Upper Computer A Tool 31 Strain Gauge 32 Restricting Member P Piezo Element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toyoji Ito 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Takami Hashimoto 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company

Claims (1)

[Scope of utility model registration request] 1. A force for detecting a processing reaction force at the time of cutting on a tool post of a tool used for the cutting, in a cutting device using a thin metal cylindrical member used for an image forming apparatus as a member to be cut. A cutting device, wherein a force sensor is installed, and the operation range of the force sensor is restricted by using a piezo element to prevent damage to the force sensor.