JPH048453A - Material weight error compensator for numerically controlled nc) machine tool - Google Patents

Abstract

PURPOSE:To adjust weight within tolerance by comparing the material weight detected at the outside of a machine with the preset reference material weight, finding the extent of under or overweight, and calculating a tool edge compensation value from the under or overweight value. CONSTITUTION:When a material subject to weight adjustment machining is mounted on a weight measuring instrument 4, material weight w1 is inputted into a comparator 6 in a numerical control system 5, whereby this material weight w1 is compared with the preinputted and stored material reference weight wo, finding the under or overweight DELTAw, and it is fed to an arithmetic circuit 7. An infeed compensation value in the X-axis direction is calculated from this under or overweight value and stored in this arithmetic circuit 7, thus machining takes place with such a value that is made up of what the infeed compensation value of the X-axis command of a program is added or subtracted to or from an X-axis positioning command value, through which such a machining as varying a work diameter phid according to the under or overweight of the material is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for correcting the position of a cutting edge when cutting is performed in order to maintain a constant weight of a workpiece.

Conventional technology For example, there are workpieces, such as engine pistons, whose weight must be kept within a predetermined allowable weight range in order to reduce noise and vibration.Most of these workpieces are made of diamond cast. Or precision castings and forgings.
Although the uniformity with respect to weight is relatively good, it is often not possible to obtain the specified weight by cutting only the necessary parts.For this reason, conventionally, as shown in Figure 2, the average weight of the material is calculated in advance using an NC lathe. The weight is adjusted by cutting the machining allowance set from the above. However, as long as the non-cut parts of the finished product remain, there are many cases where small errors remain and are not within the tolerance range, so after machining is completed, additional finishing machining, plating, and other weighting processes are performed to bring them within the tolerance range. I have to.

Problems to be Solved by the Invention The method described in the conventional description in which weighting is done so that the weight falls within the allowable weight depending on the process has the problem that it generates unnecessary processes, increases the amount of work in progress, and has a negative impact on quality. It has points.

The present invention has been devised in view of the above-mentioned problems of the prior art, and its purpose is to provide a correction device during cutting that can adjust the weight within an allowable range.

Means for Solving the Problems In order to achieve the above object, the material weight error correction device for an NC machine tool according to the present invention includes a means provided outside the machine for detecting the material weight of a workpiece, and a means for detecting the material weight of the workpiece. This device includes a comparison circuit that calculates excess or deficiency weight by comparing it with a preset reference material weight, and an arithmetic circuit that calculates a cutting edge correction amount from the excess or deficiency weight, and keeps the finished weight of the workpiece constant. .

The working weight measuring device detects the material weight of the workpiece, and compares this detected weight with a preset material standard weight.
Excess/deficiency weight with respect to the reference amount is determined, and a cutting correction value of the cutter is calculated from the excess/deficiency weight, and correction is performed by adding or subtracting it to the cutting command value.

Example An embodiment will be described with reference to FIG.

In a well-known NC lathe, a main spindle is rotatably supported on a headstock installed on the left side of a bed (not shown).
A chuck 1 is fitted onto the tip of the main shaft, and a workpiece W is gripped by gripping claws 1a of the chuck 1. A carriage (not shown) having a guide in the X-axis direction is movably placed on a guide in the Z-axis direction cut out on the bed, and a tool rest 2 is mounted on this carriage via a cross slide (not shown). It is placed movably. A turret 3 is provided on the tool rest 2 so as to be rotatable in the X-axis vertical plane, and a tool T is attached to one of a plurality of tool attachment stations on the left side of the turret 3.

On the other hand, a weight measuring device 4 and an NC device 5 are installed near the NC lathe to detect the weight w1 of a workpiece W (hereinafter referred to as a raw material) that has been machined at a necessary location and is about to undergo weight adjustment processing. In the NC device 5, a set standard weight wo is calculated by adding a predetermined machining allowance weight for weight adjustment to a predetermined product weight of the workpiece W.
a comparison circuit 6 which stores the reference weight WO and the detected weight W of the weight measuring device 4 to determine an excess or deficiency weight ΔW, and an arithmetic circuit 7 which calculates the X-axis correction amount from this excess or deficiency weight ΔW. The part A surrounded by the imaginary line is the circuit related to the present invention, and the rest is the same as the conventional circuit.

The X-axis correction amount output from the arithmetic circuit 7 is added to or subtracted from the program command value in the X-axis control circuit 8 to obtain an X-axis command value that takes the correction amount into consideration. The servo motor is driven and controlled to perform the correction.

Next, the operation of this embodiment will be explained.

Next, when the material to be subjected to weight adjustment cutting is placed on the weight measuring device 4, the material weight W1 is input to the comparison circuit 6 in the NC device 5. The input material weight W is compared with the material reference weight wo inputted and stored in advance in the comparator circuit 6, and the surplus/deficiency weight ΔW with respect to the reference weight is determined and sent to the arithmetic circuit 7. In the arithmetic circuit 7, a cutting correction amount in the X-axis direction is calculated from this excess/deficiency weight and is stored.

Next, the material on the weight measuring device 4 is gripped by the chuck gripping jaws 1a of the NC lathe, and when the start button is pressed, the main shaft is rotated, and the tool rest 2, which is waiting at a predetermined position, is rotated in the X-axis and Z-axis directions. It is moved at a rapid traverse speed and positioned at the cutting start position. The X-axis positioning command value at this time is the value obtained by adding or subtracting the depth of cut correction amount stored in the X-axis command value of the program. Cutting is performed by moving at a cutting feed rate, and the weight of the finished product remains constant by cutting with different processing diameters φd depending on the excess or deficiency of the material.

Effects of the Invention Since the present invention is configured as described above, it produces the following effects.

The weight of the material is detected by a weight measuring device, and this is compared with the standard weight of the material that is set and stored in advance to determine the excess or deficiency of the weight relative to the standard weight, and the correction amount is calculated by calculation to perform the correction. As a result, for workpieces with strict weight regulations that leave non-cutting parts, it is possible to keep all parts within the allowable weight range by performing weight adjustment processing twice, and the weighting process that was conventionally performed can be omitted. This is effective in reducing work-in-progress through process reduction and improving quality.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram including a partial block diagram of the material weight error correction device of this embodiment, and FIG. 2 is an explanatory diagram of a conventional technique showing an NC device when turning is performed for weight adjustment. . 4. Weight measuring device 6. Comparison circuit 7. Arithmetic circuit W.. Workpiece

Claims (1)

[Claims] (1) A means provided outside the machine for detecting the material weight of the workpiece; a comparison circuit that compares the detected material weight with a preset reference material weight to determine excess or deficiency weight; A material weight error correction device for an NC machine tool, characterized in that it includes an arithmetic circuit that calculates a cutting edge correction amount and maintains a constant product weight of a workpiece.