JPH0557566A - Machining unit - Google Patents

Abstract

PURPOSE:To make the recognition of a cutting state into what is real by setting up a made pattern signal in advance on the basis of cutting reaction data obtained by test cutting, comparing it with an actual cutting reaction at time of the actual cutting, and making a machining state so as to be detected by the result, in a machining unit of a metal thin-walled cylinderical member for an image former. CONSTITUTION:Plural mode patterns classified according to a cutting surface state at the time of machining, are stored in a storage means 8 of a computer 7 in advance. In addition, a force sensor 4, detecting a cutting reaction in machining, is attached to a tool rest 3. Thus the cutting reaction in operation is detected by this force sensor 4, amplifying it with a dynamic strain gauge 5, and it is inputted into the computer 7 via an analog-to-digital converter 6. The computer 7 compares it with a model pattern signal corresponding to the cutting reaction of the storage means 8 by a comparing means 9, detecting a state during the machining, and outputs a cutting control signal to a numerical control system or sequencer 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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]

2. Description of the Related Art In the field of ultra-precision cutting of photoconductor drums and magnetic disk substrates, for example, mirror finishing is usually performed. When inspecting these products, not only dimensional accuracy and shape accuracy but also whether the surface is a mirror surface is important.
In many cases, even minute scratches are not allowed.

As for the inspection of the surface condition, at present, the operator visually inspects after processing. in this way,
This requires workers to have skills and has been a problem in promoting automation of processing.

The following studies have been conducted on the inspection of the surface condition.

1) A technique for measuring the roughness of a machined surface by scattered light obtained by shining a laser beam on the surface of a workpiece (Kenji Morita, Yoichi Kawakubo: Mirror-finish surface roughness 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), Japan Society for 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, Precision Engineering Society, Industry-Academia Collaborative Research Cooperation Section Meeting, Presentation 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.Ra
hman, Chikaro Inaba: Recognition of processing environment based on heat flux measurement-Evaluation of validity of measurement results-Proceedings of Autumn Meeting of Japan Society for Precision Engineering, 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 by ultrasonic in-process sensor, Academic Meeting of Precision Engineering Society Autumn Meeting Proceedings, 1990, 585-58
6).

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

[0012]

Among these conventional techniques, those which 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 because of spatial restrictions. It's difficult. Therefore, the information detected by the sensor is not exactly the information on the processing point but has a slight time difference.

Further, cutting fluid is often used in actual machining, and its influence also becomes a problem in the optical measuring method, so that 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 focused on the processing reaction force as a parameter measured during processing. This is because 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. ..

However, when judging the processing state of the object to be cut from the data of the processing reaction force, the judgment standard has been empirically obtained by the conventional method, and the influence of the fluctuation of the processing reaction force in the actual processing is considered. It is set with a large margin to make it smaller.

Therefore, it is not suitable for detailed machining such as ultra-precision machining, which is not suitable for making a detailed determination of the machining state.

Further, if the sensor is damaged during monitoring of the processing state, it cannot be recognized, and the subsequent judgment may be inaccurate or impossible.

The present invention has been made in view of the above points, and in the field of ultra-precision cutting, provides a cutting apparatus capable of detecting and recognizing the cutting state and shape accuracy during processing in real time and feeding back to the processing. The purpose is to do.

[0021]

SUMMARY OF THE INVENTION The above-mentioned object is, in a cutting apparatus having a thin metal cylindrical member used in an image forming apparatus as a member to be cut, a processing reaction force at the time of cutting from a tool used for the cutting. Detecting means for detecting, storage means for storing a plurality of mode pattern signals classified according to a processing surface state at the time of cutting processing of the thin metal cylindrical member by the detecting means, and cutting from the detecting means Comprising a comparison means for comparing the output signal at the time of machining and a plurality of mode pattern signals stored in the storage means, and the output signal at the time of cutting and the data of the machining reaction force obtained by the preliminary trial machining. The cutting pattern of the thin metal cylindrical member is detected in real time by the comparison with the mode pattern signal set based on the comparison means. It is accomplished by milling apparatus to.

[0022]

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

The cutting device of the present invention uses a thin metal cylindrical member used in an image forming apparatus as a member to be cut, and is a photosensitive thin metal cylindrical member used in a copying machine or a laser beam printer. Body drum base 1
A lathe 2 for processing is provided with a tool rest 3. A force sensor 4 for detecting a processing reaction force during cutting is attached to the tool post 3, and the force sensor 4 detects a processing reaction force at the time of cutting from the tool A used for cutting. Is composed of.

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 storage means 8,
A plurality of mode pattern signals stored therein, which are classified according to the processing surface state during cutting, and the force sensor 4
The comparison means 9 compares the output signal obtained from the above with the output signal to detect the state during cutting. The computer 7 creates a signal for controlling the machining after detection and controls the lathe 2 NC
Digital IO board for device or sequencer 10
Send control signals via RS232C interface.

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 performed by the AD converter. It may be performed by software after AD conversion by 6, and noise can be removed by this.

To detect the processing reaction force during cutting, for example, 1989
Proceedings of the Annual Meeting of the Japan Society for Precision Engineering, Autumn Meeting, page 111-112, "Trial of Monoblock Type Three-Component Force Detection Holder for Magnetic Disk Cutting" (Yotaro Hatamura, Mitsuaki Adachi) Holders 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 confirmed 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.

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

Next, an example of detecting the processing state during cutting using this cutting apparatus will be described. The workpiece was a thin-walled aluminum cylinder corresponding to 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. Processing conditions are: spindle speed 6,000 rpm, feed 0.2 mm / re
Processed with v, notch 20 μm.

In processing the photosensitive drum substrate 1,
Defects in the surface state are important as defects that occur during processing. Specifically, there are chatter vibrations, scratches, defects due to entanglement of 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 pattern of the output signal of the processing reaction force.

When the processing reaction force is detected, it is checked whether the force sensor 4 is operating normally. Specifically, since the force sensor 4 used detects the force by converting it into strain with a strain gauge, the circuit is balanced by the dynamic strain gauge 5 before use, and the range of the output signal after the 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 disconnection, the output signal after the balance adjustment is out of the set range, and it is understood that the operation is not normal.

FIG. 2A shows the waveform of the output signal of the processing reaction force corresponding to a normal cutting state in which a mirror surface having a surface state of about 0.2S to 0.3S is obtained. The processing reaction force is detected when the processing is started, and attention is paid to the rise of the output signal of the processing reaction force to automatically determine the processing start.
Further, the output signal returns to almost zero level at the end of the processing, and by paying attention to the trailing edge of the output signal, the automatic end of the processing is determined.

FIG. 2B shows the waveform of the output signal when chatter vibration occurs. A chattering signal is generated, which causes a chattering pattern on the surface and causes a defect. Chatter occurs when the processing reaction force increases due to the wear of the cutting tool and the vibration isolation by the vibration isolation jig is insufficient. Comparing the waveform of the output signal with the case of FIG. 2A, it can be seen that the amplitude of the fluctuation of the processing reaction force gradually increases. It is often associated with chatter vibration being a resonance phenomenon.

FIG. 2C shows the waveform of the output signal when a band-shaped rubbing scratch having a width of several mm occurs. Such rubbing scratches occur when the processing reaction force increases due to the wear of the bite and the vanishing effect becomes inadequate. A characteristic of this case is that the processing reaction force has a pulse-like peak. When the processed photosensitive drum substrate is observed, a scratch is generated at a portion corresponding to the peak portion of the waveform, and the correspondence between the waveform of the output signal and the workpiece is well taken.

FIG. 2D shows the waveform of the output signal when the chips are entangled. Entanglement of chips causes scratches on the surface,
It becomes defective. It can be seen that the processing reaction force increases when the chips are entangled.

FIG. 2 (e) shows the waveform of the output signal when the uncut portion occurs. The uncut portion occurs when the raw pipe before processing is deformed, and the unprocessed portion becomes defective because it does not become a mirror surface. It can be seen that the output signal of the processing reaction force is at the zero level at the location corresponding to the unprocessed portion.

Incidentally, in FIGS. 2 (a) to 2 (e),
The sampling frequency of the data is 5 KHz, and the graph shows the obtained data in a scattered manner for easy viewing.

As described above, since the surface condition of the workpiece and the output signal of the processing reaction force are correlated, these patterns are stored in the storage means in advance and compared with the output signal obtained during cutting. As a result, the state during processing can be detected.

In each mode pattern of the processing reaction force stored in the above-mentioned storage means, the judgment standard obtained by the trial processing performed prior to the start of the continuous processing is set.

The processing reaction force judgment criterion is determined according to the flow shown in FIG.

In the trial machining, appropriate machining conditions are set on the basis of experience and achievements, and the machining is carried out after setting a temporary standard in order to cope with a trouble during the trial machining.

The trial machining is performed five times for each of the machining reaction forces in the normal cutting state, and the maximum value is Fmax.
(1), Fmax (2) ... Excluding the maximum and the minimum from Fmax (5). For example, when Fmax (2) is the maximum Fmax (3), Fmax (1),
From Fmax (4) and Fmax (5), the mean (Fmean) and variance (Fsigma) are obtained.

As a result, the upper limit reference value (Fupper) of the determination criterion
Is determined as Fupper = Fmean−α1 · Fsigma. Here, α1 is a proportional constant determined by experience and know-how.

Similarly, the lower limit reference value (Flower) is also determined as Flower = Fmean−α2 · Fsigma.

When judging the processing reaction force detected by using the upper limit reference value (Fupper) and the lower limit reference value (Flower) as threshold values, in the normal cutting shown in FIG. 2A, the detected processing reaction force is set to the set processing value. It is within the upper and lower limits of the reaction force.

In the case of chatter vibration shown in FIG. 2B, the detected processing reaction force exceeds the set upper and lower limit reference values of the processing reaction force at almost the same frequency.

In the case of occurrence of a band-shaped scraping scratch as shown in FIG. 2C, the detected processing reaction force exceeds the set upper limit reference value of the processing reaction force.

In the case where the chips are entangled as shown in FIG. 2 (d),
The detected processing reaction force exceeds both the upper limit reference value and the lower limit reference value of the processing reaction force, and exceeds the upper limit reference more frequently than the lower limit reference value. That is, the processing reaction force average value level increases.

When the uncut portion shown in FIG. 2 (e) occurs, the detected processing reaction force falls below the set lower limit reference value of the processing reaction force.

These judgments are made according to the following judgment criteria for 16 consecutive points when the processing reaction force is sampled at 5 KHz, for example.

For example, among 16 consecutive points of processing reaction force data, by comparing the frequency exceeding the upper limit reference value with the frequency lower than the lower limit reference value,

[0051]

[Table 1]

It is possible to determine the machining state as shown in, and it is also possible to determine that the machining state is abnormal when the total is 10 or more.

Each of the above frequencies is stored in the storage means, and the machining state of the workpiece is judged by comparing with each frequency obtained from the data of the machining reaction force detected in real time.

FIG. 4 shows the relationship between the fluctuation of the processing reaction force and the movement (drift) of the output signal after the processing is completed.
(A) is a range in which the processing reaction force at time t after 80% of the processing time (s) has not exceeded the upper limit reference value and does not fall below the lower limit reference value. It shows a normal machining state with zero drift.

(B) shows that the machining reaction force at time t is below the lower limit reference value and the machining reaction force after machining is below the zero level due to factors such as temperature rise of the tool. Further, (c) shows that the processing reaction force at time t exceeds the upper limit reference value and the processing reaction force has not returned to the zero level due to cooling of the temperature of the tool or the like.

In the cases (b) and (c) above, when the amount deviating from the zero level exceeds the appropriate amount, it is determined that the thermal equilibrium state of the cutting machine is broken and the cutting machine is in an abnormal moving state. ..

On the other hand, the abnormality of the force sensor 4 itself, which is a processing reaction force detecting means, is detected as follows.

FIG. 5A shows the case where the force sensor 4 is damaged during cutting, and naturally the detection of the processing reaction force becomes undetectable halfway.

When the new force sensor 4 is installed, if the force sensor 4 is normal, the machining reaction force fluctuates as shown in (b) at the start of the adjustment of zero balance, but the machining reaction is immediately stabilized at the zero level. The force can be detected.

On the other hand, if the reaction force sensor 4 is abnormal, even if the zero balance adjustment is started, an abnormal pattern signal is generated in which no processing reaction force is detected, as shown in (c).

[0061]

As described above, according to the present invention, the machining state of the work piece is judged by the objectively set severe judgment criteria, and the machining state is recognized in real time. As a result, highly reliable ultra-precision cutting is achieved. A cutting processing device that can perform processing unattended has been 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 flowchart showing a process of setting an upper limit reference value and a lower limit reference value which are judgment criteria.

FIG. 4 is a diagram showing an output waveform of a processing reaction force in which an upper limit and a lower limit reference value are set.

FIG. 5 is a diagram showing a change in an output waveform of a processing reaction force depending on a state of a force sensor.

[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 Comparison Means 10 NC Unit or Sequencer 11 Upper Computer A Tool

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

Claims (3)

[Claims] 1. A detecting device for detecting a processing reaction force at the time of cutting from 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, Storage means for storing a plurality of mode pattern signals classified according to the processing surface state at the time of cutting the thin metal cylindrical member by the detecting means, and an output signal from the detecting means during the cutting processing and the storage Comparing means for comparing a plurality of mode pattern signals stored in the means, and a mode pattern signal set based on the output signal at the time of cutting and the processing reaction force data obtained by the preliminary trial processing. A cutting processing device, wherein the cutting processing state of the thin metal cylindrical member is detected in real time by the comparison by the comparison means. 2. The cutting apparatus according to claim 1, wherein the mode pattern signal includes an abnormal pattern signal for detecting an abnormal state of the detecting means. 3. The cutting apparatus according to claim 1 or 2, wherein when the output signal from the detecting means does not allow an appropriate amount of movement during machining pause, an abnormality of the detecting means is detected.