JPS60201861A - Correction of diameter of multi-blade cutter - Google Patents

Abstract

PURPOSE:To fully automate setting and correction of the correcting amount of tool diameter by feeding back the machining accuracy of work to the correction level of the tool diameter while setting the limit of the tool diameter correction level. CONSTITUTION:To perform cutting of work while employing the setting correction of tool and to automatically measure the dimension of work upon completion. The results are compared with the dimensional allowance preset in an automatic measuring correction controller to perform automatic decision. In case of preliminary cutting, an error added with the finish margin is measured as a machining error thereby the measurement will exceed over the upper limit of dimensional allowance and since new tool is employed, the correction value is calculated from the measured value of work thus to correct the correction amount of tool in a numerical controller. Such corrected tool diameter correction amount is employed to perform machining again and if the dimension of work measured automatically upon completion of machining is within the allowance, mass production is executed while if it will exceed over the upper limit of allowance, it is corrected again and stops upon deviation from the lower limit. If the sum of correction amount exceeds over the setting level, it is decided to be the limit of service life.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for correcting the diameter of a multi-blade cutting tool, such as an end mill, in a workpiece machining process using the multi-blade cutting tool.

B. Prior Art As a prior art, contour machining of a plate cam using an end mill, which is a typical multi-blade tool, will be explained. As an example, consider contour machining of a plate cam shown in FIG. Assuming that the diameter of the end mill is d, the end mill only needs to move while rotating on an envelope E located outside the finished shape of the plate cam (3) by a distance corresponding to the radius d/2.

In actual machining, the radius error of the end mill diameter ΔT
This occurs as a shape error in the cam contour. In addition, because the end mill has a shape with extremely low rigidity due to its dimensions and structure, it bends due to cutting resistance.As a result, the center of the end mill traces a trajectory Δ8 outside the envelope E, and Δ
This results in an error of 8. Further, as the cutting time passes, the end mill cutting edge gradually wears out, so cutting is performed with a tool whose radius is smaller by the amount of wear Δω.

In this way, just thinking about the end mill will result in a maximum dimensional error of (Δγ + Δε + Δω). Therefore, in order to eliminate such dimensional errors, the following dimensional correction method is adopted in the known workpiece cutting process.

■ First, a trial cutting is performed, and the operator checks whether the dimensions of the workpiece are within predetermined control limits by measuring the workpiece. ).

(2) Next, the tool radius amount corresponding to the above-mentioned dimensional error is input into a numerical control (NC) device to perform finishing machining.

■ Measure the dimensions of the workpiece as appropriate to check the state of tool wear, and modify the NC program so that the tool movement trajectory moves inward by the amount reduced by tool wear.

At this time, if the amount of wear on the cutting edge of the tool exceeds the control limit, replace the tool with a new one.

As mentioned above, operator intervention is essential in conventional end mill processing, and the higher the required machining accuracy of the plate cam, which is the workpiece, the more difficult it is for the operator to measure the workpiece dimensions, make empirical judgments, etc. In addition, the frequency of modification of the Canadian program increases.

Thus, when machining workpieces using conventional multi-blade cutting tools,
Problems were observed in that it required a great deal of effort to manage the finished dimensions of the workpiece and the multi-blade cutting tool, and furthermore, it was difficult to manage the machining accuracy.

Purpose of the Invention The present invention completely automates the process of machining a workpiece using a multi-blade cutting tool, and also makes it possible to utilize the know-how gained through the experience of the operator as a parameter for correcting the diameter dimension of the multi-blade cutting tool. The main object of the present invention is to provide a method and apparatus for correcting the diameter of a multi-blade cutting tool.

C0 Structure of the Invention The present invention automatically measures errors in workpiece machining dimensions in a workpiece machining process using a multi-blade cutting tool, and uses the measured value as a correction amount for the diameter of the multi-blade cutting tool in a numerical control device to calculate dimensional tolerances. The first gist is a diameter correction method for multi-blade cutting tools that calculates the diameter correction amount of multi-blade cutting tools by sequentially inputting data into a comparison circuit and comparing it with a preset wear limit value for multi-blade cutting tools. It is a dimensional tolerance comparison system that has an automatic measurement calculation device connected to a measurement bar of workpiece processing dimensions to automatically measure errors in workpiece processing dimensions, and a dimensional tolerance setting device sequentially connected to the automatic measurement calculation device. Diameter correction for multi-blade cutting tools, consisting of a multi-blade cutting tool diameter correction amount calculation circuit having a correction amount constant setting device, and a tool diameter correction amount comparison circuit having a wear limit setting device for multi-blade cutting tools. The second gist is the device.

2. Embodiment FIG. 2 shows a flowchart for diameter correction of the end mill tool (2). This is done by detecting the errors (ΔT, Δ6, Δω), etc. by automatically measuring the workpiece dimensions, and inputting the errors externally as a correction value for the tool diameter correction amount of the numerical control (NC) device. This figure shows the function of setting the limit of the amount of tool wear by obtaining dimensional accuracy and further setting the limit value of the amount of tool correction.

The procedure for carrying out the method of the present invention, from trial cutting to mass production-scale cutting of a workpiece, and furthermore, setting the tool wear limit, will be explained in order.

(a) Trial Cutting ■ The tool diameter correction amount set in advance in the automatic measurement correction controller is input into the numerical control (NC) device as external data.

The above-mentioned tool correction amount is a value obtained by adding the finishing table to a percentage of the nominal diameter of the tool.

■ Perform cutting of the workpiece using the set tool compensation amount.

- After the cutting process of the workpiece is completed, the dimensions of the workpiece are automatically measured using a known detection means such as a triaxial displacement detector or a touch sensor.

■ Automatic determination is performed by comparing this measurement result with the dimensional tolerances set in advance in the automatic measurement correction controller. In the case of trial cutting, the numerical value obtained by adding the finishing allowance to the errors (Δγ, Δε, Δω) is measured as the machining error, so the measurement result exceeds the upper limit of the measurement dimensional tolerance.

(2) Since trial cutting is performed using a new tool, a correction value is calculated from the measured value of the workpiece, and the tool correction amount of the numerical control device is corrected.

This correction amount is a numerical value obtained by multiplying a constant set by the operator by the measurement calculation result, and can be considered to be a numerical value that includes the know-how of the operator in calculating the correction amount of workpiece machining dimensions or tool diameter.

(2) Cutting the workpiece again using the tool diameter correction amount corrected in this way.

■ After the re-cutting process is completed, the dimensions of the workpiece are automatically measured, and if they are within the dimensional tolerances, the process proceeds to the mass-production scale cutting process.

If the measurement result exceeds the upper limit of the dimensional tolerance,
Correct the tool diameter correction value again, and then cut the workpiece again. Furthermore, if the measurement result exceeds the lower limit of the dimensional tolerance, the machine is stopped.

(b) Mass production and tool wear limit setting After finishing the cutting process of the workpiece, the dimensions of the workpiece are automatically measured and automatically determined by comparing them with the dimensional tolerances set in advance in the automatic measurement correction controller. As a result, (1) If the machining dimensions of the workpiece exceed the upper limit of the dimensional tolerance, even if the total amount of correction added to the tool diameter correction amount so far is less than the preset tool correction amount, For example, the tool diameter correction amount is corrected and the workpiece is cut again according to the same procedure as in the trial cutting.

On the other hand, if the total amount of corrections is greater than or equal to the preset tool correction amount, it is determined that the tool has reached its service life limit, a new tool is called, and the workpiece is cut again from trial cutting according to the procedure described in the previous section. Repeat the correction program up to machining.

(II) If the machining dimensions of the workpiece exceed the lower limit of the dimensional tolerance, the machine will automatically stop.

(I[[) If the machining dimensions of the workpiece are within the dimensional tolerance, the preset tool correction amount is used to determine whether or not the tool diameter should be corrected when machining the next workpiece, based on the measurement results of the workpiece dimensions. Judgment is made by comparing with the limit value of

If there is no need for correction, replace the workpiece and continue cutting the subsequent workpiece. On the other hand, if it is necessary to correct the tool diameter, compare the total amount of corrections made so far with the amount of tool correction,
If the total amount of correction exceeds the tool correction amount, a new tool is called and cutting of the workpiece is started from trial cutting according to the procedure described in the above section (a). If the sum of the correction amounts is less than or equal to the tool correction amount, the tool diameter correction amount is corrected and the next cutting process is started. Note that this correction amount is a value obtained by multiplying a constant set by the operator by the measurement calculation result, and is considered to be a value that includes the operator's know-how in calculating the correction amount for workpiece machining dimensions or tool diameter. can be done.

According to the above-mentioned procedure, it is possible to completely automatically perform trial cutting, correcting dimensional errors of the workpiece due to tool wear, and even setting the tool wear limit.

An example of a diameter correction device for a multi-blade cutting tool suitable for carrying out the method of the present invention will be described below.

Figure 3 shows an example of a diameter correction device for a multi-blade cutting tool, such as an end mill.The measuring bar (1) has almost the same shape as a normal cutting tool, and is automatically controlled by the automatic tool change function (ATC) of the machining center. It has a structure that can be mounted on the main spindle, and the dimensions and shape of the workpiece can be automatically measured at a predetermined point in time by numerical control (NC) commands. The measurement results obtained by the measurement bar (1) are output by an automatic measurement calculation device as a calculation value (for example, the outer diameter of the plate cam, etc.) suitable for the object to be measured. This output is transmitted to a dimensional tolerance comparison circuit, and it is automatically determined whether or not the dimensional tolerance is within the dimensional tolerance set by the dimensional tolerance setting device. If the measured value of the workpiece size is within the preset dimensional tolerance, the next step of processing is performed as is. If the measured value is outside the set dimensional tolerance, the tool radius correction amount calculation circuit calculates the actual correction amount α·ΔRi. Here, ΔRi is the amount of correction of the tool diameter calculated from the automatic measurement calculation result of the workpiece dimensions. However, as described above, when a workpiece is actually machined using ΔRi as the tool diameter correction amount, the workpiece cannot be finished to accurate dimensions due to tool deflection and the like.

Therefore, the corrected tool radius correction amount α·ΔRi multiplied by the constant α input from the correction amount constant setter is input to the numerical control (NC) device as the tool radius correction amount to be actually used. Through the above process, it is possible to realize cutting of a workpiece whose dimensions are always within a preset dimensional tolerance. However, since the surface quality of the tool actually deteriorates due to wear, it is necessary to set a certain limit on the amount of correction. Therefore, in the tool radius correction amount cumulative value comparison circuit, the cumulative value of correction amount Σα・ΔRi=α(ΔR1
+ΔR2+ΔRs +----) is counted, and the cumulative value of the correction amount is repeatedly compared with the limit value ΔRIIlaχ set by the tool wear limit setting device. If the cumulative value of the correction amount is within the wear limit, the correction amount α・ΔRi
Carry out cutting and reprocessing of the workpiece according to the following. On the other hand, if the cumulative value of the correction amount exceeds the wear limit, it is determined that the tool life has been reached, and the machine is stopped or the end mill in use is automatically replaced with a spare end mill, and then the operation procedure described above is performed. Resume cutting of the workpiece according to the instructions.

Effects of the Invention As can be understood from the above explanation, by adopting the method of the present invention, setting and correction of the tool radius correction amount can be achieved in cutting workpieces that involve tool radius correction such as end mill contour machining. This can be done completely automatically.

According to the present invention, it is possible to stably ensure machining accuracy by feeding back the machining accuracy of the workpiece to the tool radius compensation value, and furthermore, by setting the limit of the tool radius compensation value, the tool diameter compensation value is automatically Wear limits can be controlled.

According to the present invention, a tool that has reached its wear limit is automatically replaced with a spare tool, and a new tool correction amount is set for the replaced multi-blade cutting tool. Therefore, it becomes possible to carry out continuous unmanned operation. Furthermore, the operator's experiential know-how regarding workpiece machining dimensions and tool diameter correction dimensions can be incorporated into the automatic control device as quantitative values set by the correction amount constant setter, resulting in higher accuracy. It is possible to carry out automatic processing of workpieces that have

[Brief explanation of the drawing]

FIG. 1 is a plan view illustrating contour machining of a plate cam using an end mill, and FIG. 2 is a flowchart of tool diameter correction in end mill machining. Further, FIG. 3 is a block diagram illustrating a tool diameter correction device in end mill processing. (1) - Measuring bar, (2) - End mill, C3>
-----One-plate cam. Patent applicant: Osaka Kiko Co., Ltd. Agent: Sho Ehara Hideo Ehara Figure 2 *Figure a

Claims (2)

[Claims] (1) During the workpiece machining process using a multi-blade cutting tool, errors in the workpiece machining dimensions are automatically measured, and the erroneous measurements are manually input to the dimensional tolerance comparison circuit as correction amounts for the multi-blade cutting tool diameter in the numerical control device. A method for correcting the diameter of a multi-blade cutting tool, comprising: calculating a diameter correction amount of the multi-blade cutting tool by comparing it with a preset wear limit value of the multi-blade cutting tool. (2) an automatic measurement calculation device connected to a measuring bar for workpiece machining dimensions to automatically measure errors in workpiece machining dimensions;
A dimensional tolerance comparison circuit having a dimensional tolerance setter sequentially connected to the automatic measurement calculation device, a correction amount calculation circuit for a diameter of a multi-blade cutting tool having a correction amount constant setter, and a wear limit setter for a multi-blade cutting tool. A diameter correction device for a multi-blade cutting tool, comprising a comparison circuit for cumulative value of cutting odor diameter correction amount.