JPH0611470B2 - Grinding machine controller - Google Patents

Description

The present invention relates to a control device for a grinder that grinds a work by a grindstone supported at the tip of a grindstone shaft.

[Prior Art] Generally, in this type of grinding machine, in order to maintain the sharpness of the grindstone well, a dressing device for correcting (dressing) the surface of the grindstone using a correction tool such as a dress diamond is attached.

As this dressing method, there is a method in which dressing is performed for each machining, but depending on the type of work, machining allowance, etc.
Since it is not necessary to dress the whetstone every time, a dress method called skip dress is adopted. This is for processing a plurality of works with one dress.

However, when this type of skip dress method is adopted, if the grindstone is clogged during skipping, grinding by the grindstone does not proceed, and a large bending force is generated on the grindstone shaft in relation to the processing speed, and the grindstone itself Therefore, there is a problem that the processed surface is tapered.

If such a phenomenon occurs for all workpieces,
It is considered that the original skip count was set incorrectly.However, if the taper does not occur for most workpieces but it occurs for some workpieces, the skip count setting is not appropriate. It is unthinkable, and in terms of production efficiency, it is preferable to keep the number of skips as large as possible.

[Object of the Invention] An object of the present invention is to control the processing speed appropriately so that a taper does not occur during skipping, thereby reliably preventing the occurrence of a taper without changing the number of skips. It is to provide a control device for the board.

[Structure of the Invention] Therefore, the inventors of the present invention have various machining allowances, which are not always constant even for the same work, and the sharpness of the grindstone depends more accurately on the machining allowance, not on the number of processed workpieces. Paying attention to the above, the stock removal amount during skipping is integrated, and when the integrated amount becomes large, the machining speed is reduced,
It is configured to compensate for the reduction in sharpness and prevent the occurrence of taper.

[Effects of the Invention] According to the present invention, since the processing speed is controlled according to the accumulated machining allowance, grinding can be performed at a processing speed according to the sharpness of the grindstone, and a force that bends the grindstone shaft acts. Since it does not occur, it is possible to reliably prevent the occurrence of taper.

[Examples] Hereinafter, examples of the present invention will be specifically described with reference to the accompanying drawings.

As shown in the overall system configuration in Fig. 1, the grinder is
A spindle 2 that holds a workpiece 1 by a chuck, a cutting table 3 that feeds the workpiece by cutting, a machining head 6 in which a grindstone 4 is replaceably attached to the tip of a grindstone shaft 5, and the machining head 6 moves back and forth in the axial direction. A whetstone table 7 for making a dressing and a dressing device 9 for dressing the whetstone 4 by a dress diamond 8 are configured as basic components.

A cutting motor 10 for cutting and feeding the cutting table 3 is controlled by a cutting control device 11.

The data required for this control are given by the pre-gauge 12 that measures the inner diameter of the workpiece before machining and the impro gauge 13 that measures the inner diameter of the workpiece 1 during machining. The outputs of these pre-gauge 12 and impro gauge 13 are: It is input to the cutting control device 11 via the gauge amplifier 14 and also to the stock removal calculation circuit 15.

The machining allowance calculation circuit 15 is selectively connected to the gauge amplifier 14 and a gap elimination device 16 provided for the machining head 6 via a changeover switch 17, and the grinding wheel 4 is used for machining. When the gap elimination device 16 detects that the workpiece 1 has come into contact with the workpiece 1 and outputs the contact signal to the surplus calculation circuit 15, the changeover switch 17 is switched to the gauge amplifier 14 side, and first, the machining detected by the pre-gauge 12 is performed. The inner diameter Di (j) of the previous work 1 is read, and then the inner diameter D (j) of the work 1 after the completion of machining detected by the impro gauge 13 is read, and the machining allowance ΔD (j) = Di (j) -D (j) is calculated, and the machining allowance ΔD (j) is calculated when one machining is completed
To enter.

A machining completion signal and a dressing completion signal are input to the machining allowance integration calculation circuit 18. The machining allowance ΔD (j) is integrated every time the machining completion signal is input, and the integrated value is obtained. (R = 1, ..., N-1, N is the number of set skips) each time, the cutting speed calculation circuit 20, the grinding power calculation circuit 21,
Output to the gauge change rate calculation circuit 22.

The three arithmetic circuits 20, 21, 22 are selectively connected to the cut control device 11 by a changeover selection switch 23.

Cutting speed arithmetic circuit 20 is for setting the cutting speed Vc in accordance with a machining allowance integrated value I _R, if the allowance integrated value I _R as FIG. 3 (a) is changed, FIG. 3 (b ), The cutting speed Vc is decreased stepwise from the initial speed Vo according to the stock removal integrated value I _R.

When the cutting speed calculation circuit 20 is selected, the cutting control device 11 drives and controls the cutting motor 10 so that cutting is performed at the set cutting speed Vc.

Further, when the grinding power calculating circuit 21 has been selected constant power grinding is performed, will be the power value with respect to the processing head 6 at that time is set according to the cumulative allowance value I _R, cutting control unit 11 Performs feedback control of the cutting motor 10 so that the driving power of the processing head 6 becomes the set power value.

Furthermore, when the gauge change rate calculation circuit 22 is selected, the gauge change rate Gc is set according to the stock removal accumulated value I _R.

This method will be described with reference to the flow shown in FIG. 2. First, the initial gauge change rate Gco is set in advance.

On the other hand, the stock removal calculation circuit 18 integrates the stock removal ΔD (j) input from the stock removal calculation circuit 15 for each machining completion signal,
The integrated value Is output to the gauge change rate calculation circuit 22.

The gauge change rate calculation circuit 22 sets the gauge change rate Gc by the following equation.

Gc = Gco ± α · I _R where, alpha is a constant that indicates the amplification factor.

Based on the gauge change rate Gc set in this way, feedback control of the cutting motor 10 is performed so that the machining dimension increase speed detected by the in-process gauge 13 approaches the gauge change rate Gc. Control comes into play.

By doing so, the processing speed is controlled in consideration of the sharpness of the grindstone 4 even during the skip, so that the grindstone shaft 5
No excessive force is applied to the blade, correct grinding is performed, and the taper is not generated.

When the dressing is performed once, the dressing operation circuit 15 and the like are reset in response to the dressing completion signal,
The next grinding is started and the same control as above is executed.

The stock removal calculation may be calculated from the relationship between the finish reference dimension and the initial values of the pre-gauge and the impro gauge, or the feed position when the gap elimination device is operating.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention, FIG. 2 is a flow chart diagram showing a calculation flow of the system,
FIGS. 3 (a) and 3 (b) are graphs showing changes in the stock removal amount I _R and setting patterns of the cutting speed Vc corresponding thereto, respectively. 1 ... Workpiece, 3 ... Cutting table, 4 ... Grindstone, 5 ... Grindstone axis, 6 ... Machining head, 7 ... Grindstone table, 9 ... Dressing device, 11 ... Cutting control device, 12 …… Pre-gauge, 13 …… Impro gauge, 15 …… Grinding allowance calculation circuit, 18 …… Grinding allowance calculation circuit, 20 ・ ・ ・ Cutting speed calculation circuit, 21 …… Grinding power calculation circuit, 22 …… Gauge change rate calculation circuit .

Claims (1)

[Claims] 1. A grinding machine having a grindstone shaft provided with a grindstone at its tip, a cutting feed device for relatively feeding a work to the grindstone, and a grindstone correcting device for performing grindstone correction after grinding a plurality of works. , The number of skips detector that detects the number of workpieces processed from the grindstone correction, the work allowance detection means that detects the work allowance, and the work allowance detected by the work allowance detection means between the skips after the grindstone correction A control device for a grinding machine, comprising: a work stock removal detecting integrator, and a machining speed control device that reduces a machining speed according to an increase in stock removal stock.