JPH0771787B2 - Grinding control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention is a constant power grinding type grinding control for controlling the cutting speed so that the grinding power becomes constant in each grinding process such as black skin grinding and rough grinding. Regarding the device.

[Prior art]

Conventionally, when grinding, for example, the inner surface of a work piece (hereinafter, referred to as a work), the grindstone is rotated and axially fed to be inserted into the work. Rough grinding, finish grinding, spark out, etc. (black skin grinding may be performed before rough grinding) are performed. And as a cutting speed control method in this grinding, conventionally, there is constant power grinding as described in JP-A-51-140282, which is, for example,
The cutting speed of each grinding process of rough grinding and finish grinding is controlled by feedback so that the grinding power becomes a constant value for each grinding process. For example, rough grinding is faster than finish grinding. Since it cuts in, the power is controlled accordingly.

In the conventional constant power grinding, the grinding power for each process is set for each work type for different kinds of works, for example, works different in material, size or heat treatment in the previous process. For the same type of work, the same power is used for all works. The reason for setting the same electric power in this way is that it is considered that the conditions of the machined surface will be the same for the same type of work. However, in reality, when the electric power is controlled to the same electric power, the grinding accuracy may be different for each work even for the same kind of work, so that there is a problem that the grinding accuracy is low in some cases. In this way, the processing accuracy varies, even for the same type of work, as the cutting speed of the grindstone is faster, the cutting depth of the grindstone increases and the load applied to the grindstone increases, resulting in damage to the grindstone. Is because it is expressed by the amount of work, that is, (working amount x load), and therefore grinding wheel damage such as clogging changes due to changes in the grinding allowance, and there are things that further change the sharpness of the grinding wheel, etc. Conceivable. And, performing low power grinding with a grindstone with reduced sharpness means increasing the grindstone pressing force on the workpiece, and as the grindstone pressing force increases, the bending of the grindstone shaft also increases and the machining hole becomes tapered. That will lead to deterioration in accuracy. This deterioration in accuracy can be avoided by performing grinding stone dressing for recovering the sharpness of the grinding stone, but increasing the number of dressings means shortening the life of the grinding stone.

[Object of the Invention]

The present invention has been made in view of the above conventional problems, and in a grinding control device that performs a skip dress cycle that processes several workpieces with one dress, it is possible to suppress grindstone damage and extend the grindstone life. At the same time, it is an object of the present invention to provide a grinding control device capable of stabilizing and improving grinding accuracy.

[Structure and Action of Invention]

In the constant power grinding, the present inventor diligently studied the cause of fluctuation in grinding accuracy even with the same kind of work, and found the following transitions. That is, (a) in general, the workpiece has a variation in its unmachined diameter, and therefore the machining allowance, which is the difference between the unmachined diameter and the finished machining diameter,
The so-called machining allowance varies among the works, but in the case of the same type of work, the larger the machining allowance, the larger the grindstone damage such as clogging, the sharpness of the grindstone deteriorates, and the grinding accuracy decreases.

(B) Therefore, in order to achieve the above-mentioned object, it is necessary to obtain a machining allowance for each work, and for a work having a large machining allowance, grinding control should be performed with a smaller set power, but conversely, for a work having a small machining allowance. It suffices to perform grinding with a large set power.

Therefore, the present invention provides a grinding control device for performing constant power grinding, as shown in the functional block diagram of FIG.
A grinding device 1 for grinding a work, a cutting control means 61 for controlling the cutting speed of the device 1 so that the grinding power is constant in each grinding process, and a work sensor 62 for obtaining a work allowance. , And the stock removal calculation means 63 and the cutting control means 6
The grinding power correction means 64 for correcting the grinding power by 1 is provided.

In the present invention having the above-mentioned configuration, the workpiece sensor 62 and the machining allowance calculation unit 63 determine the machining allowance, and the grinding power correction unit 64 cuts the grinding power correction signal to reduce the grinding power as the machining allowance increases. Given to means 61,
As a result, a workpiece with a large machining allowance is ground at low power, that is, at a low speed, and grinding stone damage is suppressed by that amount, improving grinding accuracy, and conversely, a work with a small machining allowance is ground at high power, that is, at a high speed. The cycle time can be shortened without reducing the grinding accuracy.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

2 and 3 show a grinding control device according to an embodiment of the present invention. In FIG. 2 showing the overall structure, 1 is a grinding device for grinding the inner surface of a work W, which is a grindstone. It is composed of a drive device 7, a work drive device 14, and a grindstone dressing device 15.

The grindstone table 2 of the grindstone drive device 7 is slidably mounted on the upper surface of the bed 1a in the left-right direction in the figure, and a female screw box (not shown) fixed to the lower surface of the grindstone table 2 is for moving the grindstone table. The ball screw 3 is screwed together, and the grindstone feed motor 4 whose output shaft is connected to the ball screw 3 is fixed to the bed 1a. A wheel head motor 5 is mounted on the grindstone table 2, and a grindstone 6 is connected to an output shaft of the motor 5.

The work table 8 of the work driving device 14 is placed on the upper surface of the bed 1a so as to be slidable in the vertical direction in the figure, and a female table (not shown) fixed to the lower surface of the work table 8 is used for moving the work table. A ball screw 9 is screwed, and a cutting feed motor 10 having an output shaft connected to the ball screw 9 is fixed to the bed 1a. A headstock 11 for chucking the work W is mounted on the work table 8, and the headstock 11 and a drive motor 12 mounted in the vicinity thereof are connected by a drive belt 13.

The grindstone dressing device 15 is of a swing type mounted on the work table 8, and a dressing tool 15b is attached to the swing arm 15a.

Reference numeral 20 denotes a cutting control device which receives the cutting speed and the cutting amount signal from the pulse encoder 28 so that the cutting speed and the cutting amount of the grinding device 1 become set values, and the wheel head motor 5 This is for performing feedback control so that the grinding power by the method becomes a predetermined value.

In FIG. 3 showing the block configuration of the cutting control device 20 and the like, 21 is a cutting speed setting unit for setting each cutting speed according to the type of work in semi-fast feed, black skin feed, and fast feed, and 31 is Similarly, a grinding power setting unit for setting rough grinding power Rpo and finishing grinding power Fpo according to the type of work, 22 is a semi-rapid feed amount, black skin grinding amount, rough grinding amount, and finishing grinding amount according to the type of work. It is a cutting amount setting part to set the size,
Each of these set values is determined based on the work of the average stock removal S. 23, 24, and 32 are a cutting speed selection unit and a cutting amount selection unit that select the cutting speed setting value, the cutting amount setting value, and the grinding power setting value, respectively, according to the selection signal E from the selection signal creating unit 25. , A grinding power selection unit, and the selection signal E is generated according to the sequence signal F from the sequence control unit 26. Further, 27 is a drive control signal creation unit, which uses the set value selected by the cutting speed selection unit 23 and the cutting amount selection unit 24 as a target value, the rotation speed of the cutting feed motor 10,
The current value from the pulse encoder 28 for detecting the rotation amount is compared, and a drive control signal C for feedback-controlling the cut feed motor 10 is created and output so that they match each other.

33 is a grinding power control signal generation unit, which is a grinding power set value from the power selection unit 32 and a power detection device 60.
From the current wheel head motor 5 to produce and output a grinding power control signal C'according to the difference between the two values.
Further, 34 is a selector switch for selectively passing the control signal C'and the drive control signal C according to the selection signal E, and 29 is a drive signal D corresponding to the drive control signal C or the grinding power control signal C '. It is a driver that outputs.

Reference numeral 30 denotes a gap eliminator that detects that the grindstone 6 has come into contact with the surface of the workpiece W to be processed from the change in the electric power of the wheel head motor 5. This is the inner diameter of the workpiece W at the start of grinding,
That is, it is a work sensor for detecting the unmachined inner diameter Ds.

40 is the amount of increase / decrease B of the stock removal B'of the work W with respect to the average stock removal S
Is a stock removal computing device, which is a stock removal computing unit 41
And a stock removal amount calculation unit 42. The stock removal calculation unit 41 is the grindstone 6 from the gap eliminator 30.
And a workpiece W contact detection signal, an unmachined inner diameter Ds obtained from a cutting feed position at the time of detection and a preset finishing inner diameter Df are used to calculate the machining allowance B of the workpiece W by the following formula (1). ′ Is calculated.

B ′ = (Df−Ds) / 2 (1) Further, the stock removal amount increase / decrease calculation unit 42 calculates the increase / decrease amount B = SB ′ with respect to the average stock removal S of the stock removal B ′.

50 is a grinding power correction device, which is set as above,
Set the rough grinding power Rpo for the workpiece with the average stock removal S according to the stock removal increase / decrease amount B by the following formula (2).
It is for correcting to.

Rp = Rpo-K * B (2) Next, the function and effect will be described.

Here, FIG. 4 is a characteristic diagram showing the relationship between the machining allowance increase / decrease amount B and the actual rough grinding power Rp, and the slope of the characteristic line is the above equation (2).
Corresponding to the proportional coefficient K of the work, which is an experimental value determined by the type of the work, that is, the material, size, or pre-processing, for example, the degree of heat treatment. As is clear from the figure, the actual rough grinding power Rp is Rpo which is the same as the set value in the work with the stock removal increase / decrease amount B of 0, that is, the average stock removal S, and in the work of B ₁ and B _2.
Rp ₁ and Rp ₂ , and the larger the stock removal, the lower the power consumption.

In the apparatus of the present embodiment, various cutting speeds, cutting amounts, and grinding powers are set by the setting units 21, 22, and 31, and when the workpiece W is loaded on the headstock 11 and the apparatus is started, the sequence The sequence signal F from the control unit 26 is the selection signal creation unit
The selection signal E for selecting the semi-rapid feed from the creating unit 25 is input to the cutting speed selecting unit 23, the cutting amount selecting unit 24, the grinding power selecting unit 32 and the changeover switch 34. Then, first, the setting semi-rapid feed speed and the set semi-rapid feed amount, which are the target values, are selected in both the selection sections 23 and 24, and the changeover switch 34 is switched to the drive control signal creation section 27 side. In addition,
In this case, there is no selection output from the grinding power selection unit 32. Then, the selected both target values are compared with the current value input from the pulse encoder 28 in the drive control signal creating section 27, and the drive control signal C corresponding to the difference between the two is created. The drive signal D corresponding to the control signal C is input to the cutting feed motor 10 via 34, whereby the work W is fed in the direction perpendicular to the axis. Further, the cutting speed and the cutting amount at this time are fed back to the drive control signal creating unit 27 via the pulse encoder 28, and thus the predetermined cutting speed and feeding amount are controlled.

Then, in the above-mentioned semi-rapid feed, the inner surface of the work W is the grindstone 6
When you touch, the target value and the current value will match,
This coincidence signal G is input to the selection signal creating section 25, and a signal E for selecting the black skin cutting speed and the black skin grinding amount from the creating section 25.
Is input to each of the selection units 23 and 24, and black skin grinding is performed in the same manner as above. When the black skin grinding is completed, the selection signal E becomes a signal for selecting the rough grinding. Therefore, the grinding power selecting section 32 selects the rough grinding power, and the changeover switch 34 is switched to the grinding power control signal creating section 33 side. .

Further, the gap eliminator 30 detects the contact between the workpiece W and the grindstone 6 in the above-described semi-feeding from the change in the electric power of the wheel head motor 5 at this time, and this detection signal is used as the stock removal calculation unit 41.
Entered in. Considering a work in which the stock removal B ′ is larger than the average stock removal S by B ₁ , in the stock removal calculation unit 41,
The stock removal B ′ is calculated by the above equation (1), and the amount of increase / decrease with respect to the average stock S, in this case, the increase B ₁ is calculated, and this stock removal increase B ₁ is input to the grinding power correction device 50. Then, in the apparatus 50, the set rough grinding power Rpo is corrected to the actual rough grinding power Rp ₁ according to the stock removal increase amount B ₁ by the equation (2), and the power Rp ₁ is input to the grinding power selection unit 32. Since the rough grinding selection signal is input to the selecting unit 32 as described above, the actual rough grinding power Rp ₁ is input to the grinding power control signal creating unit 33, where the actual rough grinding power Rp ₁ is input.
A grinding power control signal C'corresponding to the difference between ₁ and the detected grinding power P from the power detection device 60 is created.
Is input to the driver 29 via the changeover switch 34, and the feed motor 10 is driven by the drive signal D corresponding to the control signal C '.
Is controlled so that the grinding power P of the wheel head motor 5 corresponds to the actual rough grinding power corresponding to the increased stock removal B _1.
Cutting control is performed so that it becomes Rp ₁ .

Further, when the rough grinding is completed, next, finish grinding is also performed by constant power control. In this case, the set finish grinding power Fp set based on the work of the average machining allowance S is used.
Depth control is performed with o as a target value. Thus, in the present embodiment, the black skin grinding is controlled by constant speed control, and the rough grinding and finish grinding are controlled by constant power control. Is performed.

As described above, in this embodiment, the stock removal of the work W is obtained, and the cutting control is performed with the actual rough grinding power that is smaller as the stock removal corresponding to the size of the stock W is larger. Suppressing wheel damage and maintaining the sharpness of the wheel, as a result, the wheel life can be extended, grinding accuracy can be improved, and conversely, a workpiece with a small machining allowance can be ground with a large grinding power, so the cycle time can be reduced accordingly. Can be shortened.

In the embodiment, the gap eliminator 30 is described as an example of the work sensor, but the work sensor may be, for example, a pre-gauge that measures the inner diameter of the work W before loading or an in-process gauge that measures the inner diameter of the work W after loading. Further, in the above-described embodiment, only the rough grinding power is corrected according to the stock removal, but the black skin grinding power may be further corrected, and by doing so, the grinding accuracy can be further improved. Furthermore, in the above embodiment, the case where the inner surface of the work is ground has been described, but the present invention can of course be applied to the outer surface grinding.

〔The invention's effect〕

As described above, according to the grinding control device of the present invention, since the work allowance is determined and the grinding power is controlled according to the allowance, it is possible to suppress the grindstone damage even in the work with a large work allowance, and the grindstone life. It is possible to extend the grinding angle and improve the grinding accuracy.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is an overall configuration diagram of a grinding control device according to an embodiment of the present invention, FIG. 3 is its block configuration diagram, and FIG. −
It is an actual rough grinding electric power characteristic diagram. 1 ... Grinding device, 20 ... Depth control device, 30 ... Gap eliminator (work sensor), 40 ... Stock removal computing device,
50 ... Grinding power correction device, 61 ... Cutting control means, 62 ...
Work sensor, 63 ... machining allowance calculation means, 64 ... grinding power correction means.

Claims (1)

[Claims] 1. A grinding device for performing a grinding process on an inner surface or an outer surface of a workpiece, a grinding power detecting means for detecting a grinding power, and a cutting speed of the grinding device detected by the grinding power detecting means. The cutting control means for controlling the electric power to be constant in each grinding process, the work sensor for detecting the inner diameter or the outer diameter of the workpiece, and the unprocessed diameter and finish of the workpiece from the detection output of the sensor. A machining allowance calculation unit that calculates the machining allowance that is the difference from the machining diameter, and a machining allowance increase and decrease amount calculation unit that calculates the machining allowance increase / decrease amount with respect to the average machining allowance that is the difference between the average value of the unmachined diameters of multiple workpieces and the finishing machining diameter. And a grinding power correction means for providing the cutting control means with a grinding power correction signal for making the grinding power smaller than the set grinding power for the average machining allowance as the amount of increase or decrease of the machining allowance increases. Characterizing Cutting control device.