JPH02237703A - Diamond tool and cutting device using this tool - Google Patents

Abstract

PURPOSE:To cut and machine a workpiece with high accuracy by forming a conductive iron-implantation layer on rake face and the cutting edge of a tool, applying a voltage between the conductive workpiece and the conductive layer to measure a current value, and detecting a contact point of the tool with the workpiece based on the change in the current value. CONSTITUTION:When a voltage is applied between a diamond tool 2 and a workpiece 1, the tool 2 is brought close to the workpiece 1 by a microvibrating tool rest 4, and a cutting edge contacts the workpiece 1, a current C flows into a circuit 12. A ammeter 11 detects the current value C and outputs it to a control device 13. When the current value C becomes larger than a threshold value, the control device 13 judges that the cutting edge came into contact with the workpiece 1, drives a driving piezoelectric element 45 through a piezoelectric element power supply 5, referenced from this contact-position, and controls the micro-depth of cut by detection signals of a displacement gage 6. Since the current flows in the circuit 12 at an instant when the cutting edge wakes contact with the conductive workpiece 1, a contact point can be detected with high accuracy, and thereby the cutting accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a diamond cutting tool used for precision cutting and a cutting device that makes minute cuts using this diamond cutting tool.

[Conventional technology] When performing micro-cutting with a diamond cutting tool, the depth of cut is set by visually determining the point of contact between the diamond cutting tool and the surface of the workpiece, and then using the cutting device of the machine tool to set the depth of cut. Only quantitative cuts are made. However, the accuracy of visually determining the contact point is only a few meters at most, and the resolution of the cutting device is also
Since it is about Lm, submicron cuts cannot be made in this direction. Therefore, for the purpose of controlling the depth of cut below lpm, the contact point between the diamond bit and the workpiece surface was
．． A method has been proposed in which the contact point is detected with an accuracy of 1 pLm or less and the depth of cut is set based on the contact point (1932).
(Refer to p. 737 of the Proceedings of the 3rd Annual Japan Society for Precision Engineering Spring Conference Academic Lectures). This is shown in Figure 3. In the figure, (1) is the workpiece, (2) is the diamond cutting tool, (3) is the reaction force detection piezoelectric element that detects the reaction force applied to the diamond cutting tool (2), and (4) is the fine movement tool stand. A notch (4C) is provided in the steel block to form parallel leaf spring parts (4d) and (4e), and the fixing part (4a) is
) and a fine movement part (4b), and a notch (4
C) incorporates a drive piezoelectric element (4f). (5) is a piezoelectric element power source that applies voltage to the driving piezoelectric element (4f), (6) is a displacement meter using an electric micrometer that detects the amount of displacement of the fine movement part (4b), and (7) is a displacement meter that detects A displacement current converter converts the amount of displacement into a current value, (8) is an AC voltmeter that measures the reaction force of the piezoelectric element (3) for reaction force detection as a voltage, and (9) is an arithmetic unit. ) and the detected reaction force, and the specified cutting depth is applied to the drive piezoelectric element (4f) via the piezoelectric element power source (5). Next, we will explain the operation. The computing unit (9) first monitors the reaction force detection signal a from the reaction force detection piezoelectric element (3) and detects the drive piezoelectric element (
Gradually increase the applied voltage b to the fine movement part (4b)
by displacing the diamond bit (2) to the workpiece (1).
). While the diamond cutting tool (2) is not in contact with the workpiece (1), the level of the reaction force detection signal a is almost constant at the noise level, as shown in characteristic part A in Figure 4, but when the workpiece From the time of contact with object (1), both parties (2)
．． During (1), a reaction force occurs as a thrust force of the cutting resistance, and rises as shown in characteristic B in Fig. 4. Arithmetic unit (9
) determines that the diamond cutting tool (2) has contacted the workpiece (1) when the level of the reaction force detection signal a reaches a predetermined value C, and calculates the signal at the rising part B of the characteristic by the least squares method. It approximates a straight line, and the intersection point D between this straight line and the almost flat characteristic part A is located between the diamond tool (2) and the workpiece (
1) Perform calculations regarding the point of contact with. Using this contact point D as a reference, the driving piezoelectric element (4f) is driven via the piezoelectric element power source (5) so as to displace the fine movement part (4b) by the specified depth of cut, and the displacement meter (6) Control is performed so that the detected displacement amount becomes the instructed depth of cut. [Problem to be solved by the invention] However, since conventional cutting devices detect the contact point from the reaction force as a thrust force of the cutting resistance, the reaction force is detected unless the diamond bit (2) is made to cut. cannot be detected. Therefore, the intersection point D with the straight line calculated by the method of least squares does not match the true point of contact. In other words, in principle,
It is not possible to detect exact contact points. As a result, there was a problem that high-precision cutting could not be performed. In addition, it is necessary to perform high-speed calculation using the least squares method, which complicates the function of the calculator (8).Furthermore, in order to reduce the detection error of the contact point, it is necessary to use a piezoelectric sensor with high sensitivity and high rigidity for reaction force detection. There was also the problem that the element (3) was required, leading to an increase in cost.

This invention was made with the aim of solving the above-mentioned problems, and aims to provide a cutting device that can cut conductive workpieces with high precision, and a diamond cutting tool for use in the cutting device. [Means for Solving the Problems] In order to achieve the above object, the diamond cutting tool of the present invention is characterized in that a conductive ion-implanted layer is formed on the rake face and the edge of the cutting edge. Further, the cutting device of the present invention applies a voltage between the diamond cutting tool and the conductive workpiece to determine the electric resistance value between the diamond cutting tool and the workpiece or the current flowing between the two. means for detecting the point of contact between the diamond cutting tool and the workpiece based on the change in the electrical resistance value or current value, and a drive control means for causing the diamond cutting tool to cut a predetermined amount from the detected contact point. It is characterized by the following. [Operation] According to the present invention, not only the workpiece but also the diamond tool has conductivity, so by applying a voltage between the diamond tool and the workpiece, the electric resistance value or The value of the current flowing between the two can be measured. This electrical resistance value or current value changes rapidly the moment the diamond cutting tool and the workpiece come into contact.
By detecting this change point, the contact point can be easily detected. Therefore, the contact point can be detected more accurately than the conventional method of determining the contact point based on cutting resistance. Furthermore, the electrical resistance value and current value described above are relatively easy to measure, and an expensive piezoelectric element for detecting reaction force is not required. [Example] An example of the present invention will be described below with reference to the drawings. Figure 1 is an enlarged view showing the cutting edge of the diamond cutting tool (2), where (2a) is the rake face, (2b) is the flank face, and (2c) is the cutting edge.
is the cutting edge, and these rake face (2a) and flank face (2a)
b) and the edge of the cutting edge (2C), an ion-implanted layer (2d) of, for example, nitrogen or argon is formed. This ion implantation layer (2d) is a diamond bite (2).
Ions such as nitrogen and argon are implanted between many carbon molecules on the surface of the ion-implanted layer (2d
) makes the cutting edge of the cutting tool (2) conductive. In FIG. 2, the diamond cutting tool (2) has a shank (2e), for example, a fine movement part (4b) of a fine movement tool stand (4).
), (10) is a DC power supply that applies voltage between the ion-implanted layer (2d) of the diamond cutting tool (2) and the conductive workpiece (1). ，
(11) is an ammeter, which is a circuit containing a DC power supply (10) (
(13) is a control device that is equipped with a comparator (not shown), which measures the current value C measured by the ammeter (11) and a preset value. The contact between the diamond tool (2) and the workpiece (1) is determined by comparing the threshold value. The rest of the configuration is the same as that of the conventional example shown in FIG. 3, and the same or corresponding parts are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

Next, explain the action. First, with a voltage applied between the diamond cutting tool (2) and the workpiece (1), use the fine movement tool stand (4) to
Bring the diamond cutting tool (2) close to the workpiece (1) and measure the current value of the circuit (12) with an ammeter (11). Eventually, when the cutting edge (2C) of the diamond cutting tool (2) comes into contact with the workpiece (1), the circuit (12)
is closed and current flows.

The ammeter (l1) detects the current value C of the circuit (l2) and outputs it to the control device (13). The control device (13) compares the input current value C with a threshold value, and when the current value C becomes larger than the threshold value, the cutting edge ridge (2C) of the diamond cutting tool (2) is damaged. It is determined that the workpiece (1) has been contacted, and the driving piezoelectric element (4f) is driven using the contact position (contact point) as a reference via the piezoelectric element power supply (5), as in the conventional example shown in Fig. 3. Then, it is controlled so that a minute amount of incision is made as instructed by the detection signal of the displacement meter (6). In this way, in the above embodiment, the ion-implanted layer (2d) was formed on the rake face (2a) and the cutting edge ridge (2c) of the diamond cutting tool (2).
Conductive workpiece (1) and diamond tool (2)
The moment the cutting edge ridge (2C) of the circuit (12) comes into contact with the
Since current flows through the contact point, the contact point can be detected with high accuracy. Therefore, cutting accuracy is improved compared to the conventional method.

In addition, the current value C changes rapidly at the moment of contact. Therefore, the control device I! Current value C determined by the comparator in (13)
Since the point of contact can be easily detected by comparing the value and the threshold value, there is no need to perform calculations using the conventional method of least squares, which simplifies the structure of the control device (l3). Moreover,
Measuring the current value C does not require an expensive piezoelectric element, unlike conventional reaction force measurement. In this way, the control device i! (1
3) The structure is simplified and a piezoelectric element for detecting reaction force is not required, so the cost of the cutting device can be reduced.

By the way, in the above example, the current value of the circuit (l2) was measured, but instead of this, the electrical resistance value between the diamond cutting tool (2) and the workpiece (1) was measured, and this resistance value was measured. Contact points may be detected based on changes in . Further, in the above embodiment, the rake face (2a) . A-grained surface (2b) and cutting edge ridge (
The ion implantation layer (2d) was formed on the rake face (2a) and the cutting edge ridge (2c).
C). Note that the implanted ions are not limited to nitrogen or argon, but may be any ion that can impart conductivity to the diamond bite (2). [Effects of the Invention] As explained above, according to the present invention, since an ion-implanted layer is formed on the rake face and cutting edge of a diamond cutting tool, contact points can be detected extremely accurately for conductive workpieces. Moreover, since it is easy to use, it is possible to perform fine cutting with high precision, and it is also possible to simplify the configuration of the cutting equipment and reduce costs.

[Brief explanation of drawings]

Fig. 1 is an enlarged sectional view of the tip of a diamond cutting tool showing an embodiment of the present invention, Fig. 2 is a schematic diagram of a cutting device which is an embodiment of the invention, and Fig. 3 is a diagram of a conventional cutting device. The schematic configuration diagram and Figure 4 are characteristic diagrams showing changes in the reaction force detection signal level with respect to the feed amount of the cutting tool. (1) Workpiece, (2) Diamond cutting tool, (2a) Rake face, (2C) Cutting edge, (2d) Ion-implanted layer, (4 )...Fine movement tool stand, (4f)...Piezoelectric element for drive, (5)...Piezoelectric element power supply, (6)...Displacement meter, (7)...Displacement current converter, ( 10)...DC power supply, (l1)...Ammeter, (13)...Control device. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A diamond cutting tool in which a conductive ion-implanted layer is formed on the rake face and the edge of the cutting edge. (2) A fine adjustment tool stand that holds a diamond cutting tool with a conductive ion-implanted layer formed on the rake face and cutting edge, and a combination of the diamond tool's conductive ion-implanted layer and the conductive workpiece. means for applying a voltage between the diamond tool and the workpiece and measuring the electrical resistance value between the diamond tool and the workpiece or the current value flowing between the two; A cutting device comprising means for detecting a position at which the diamond bit contacts a workpiece, and means for driving and controlling the fine movement tool body so that the diamond cutting tool cuts by a predetermined amount from the detected position of contact.