JPH0649273B2 - Grinding control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a constant dimensional change rate for controlling the cutting speed so that the dimensional change rate, which is the cutting amount per unit time, becomes constant in each grinding process. The present invention relates to a grinding type grinding control 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. Grinding is performed under the grinding conditions suitable for each grinding process such as black skin grinding, rough grinding, and finish grinding. Conventionally, as a method of controlling the cutting speed in each grinding process, there has been a constant speed grinding, which is a constant cutting process for each grinding process determined in consideration of grinding conditions such as a machined surface state in each grinding process. This is a method of controlling the cutting speed by the speed. However, it is generally unavoidable that the grindstone shaft bends due to the pressing force during grinding, and there is a clearance due to this bending, so in constant speed grinding, the actual grinding speed of the workpiece does not match the cutting speed.

Therefore, as a cutting speed control method capable of solving the problem that the cutting speed and the grinding speed do not coincide with each other, conventionally, there is a constant dimension change rate grinding, which detects the size of the processed portion of the workpiece and changes the dimension. Rate, that is, the method of controlling the cutting speed so that the actual grinding amount per unit time is constant for each grinding process.For example, rough grinding is for cutting at a higher speed than finish grinding, We try to control at a large rate of change.

In the conventional constant dimensional change rate grinding, the dimensional change rate for each of the above-mentioned grinding steps should be reset for each work type for different kinds of works, for example, for works having different sizes, materials, or heat treatment in the previous process. However, the same type of work has the same dimensional change rate for all works. However, when controlling to the same dimensional change rate, even if the same kind of work, the grinding accuracy may differ from one work to another, and the conventional grinding control device has a problem that a work having a low grinding accuracy occurs. In this way, the machining accuracy changes because the cutting speed of the grindstone is faster, the cutting depth of the grindstone is increased and the load applied to the grindstone is increased, even if it is the same kind of work, and the damage of the grindstone is increased. Since it is represented by the work amount, that is, (working amount x load), it is considered that there is something that changes the grinding wheel damage such as clogging due to changes in the grinding allowance, and changes the sharpness of the grinding wheel. .

[Object of the Invention]

The present invention has been made in view of such conventional problems, and aims to provide a grinding control device capable of suppressing the grinding wheel damage and extending the grinding wheel life, stabilizing the grinding accuracy, and improving the grinding accuracy. There is.

[Structure and Action of Invention]

The present inventor diligently studied the cause of variation in grinding accuracy even in the case of the same kind of work in the above-mentioned constant dimension change rate grinding, and found the following points. That is, (a) Generally, the workpiece has a variation in its unmachined diameter,
Therefore, the machining allowance, which is the difference between the unmachined diameter and the finish machining diameter, causes variations in the so-called machining allowance.However, in the case of the same type of work, the larger the machining allowance, the greater the damage to the grindstone such as clogging. As a result, 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 with a large machining allowance, grinding control should be performed with a small dimensional change rate, but conversely for a work with a small machining allowance. It suffices to grind with a large dimensional change rate.

Therefore, the present invention relates to a grinding control device for performing constant dimension change rate grinding, as shown in the functional block diagram of FIG.
The cutting speed is controlled so that the dimensional change rate is constant in each grinding process, and the current dimensional change rate calculation unit that calculates the current dimensional change rate from the output signal from the in-process gauge and the current dimensional change A cutting control means 61 having a dimensional change rate control signal producing section for producing a dimensional change rate control signal by comparing the rate with a set dimensional change rate, and a work sensor 62 for obtaining a work allowance. A machining allowance calculating unit 63 including a machining allowance calculating unit for calculating a machining allowance from the detection output of the work sensor 62, and a machining allowance increasing / decreasing amount calculating unit for calculating a machining allowance increasing / decreasing amount with respect to an average machining allowance of the workpiece.
A dimensional change rate correcting means 64 is provided for correcting the dimensional change rate by the cutting control means 61 to be smaller than the dimensional change rate for the average stock removal as the stock removal increase / decrease amount increases.

In the present invention having the above-described configuration, the workpiece sensor 62 and the machining allowance calculating unit 63 determine the machining allowance, and the dimensional change rate correcting unit 64 increases the dimensional change rate as the dimensional change rate becomes larger than the average dimensional change rate. A dimensional change rate correction signal for reducing the size is given to the cutting control means 61, whereby a workpiece with a large machining allowance has a small dimensional change rate,
In other words, it is ground at a low speed, the grindstone damage is suppressed by that amount, and the grinding accuracy is improved. Conversely, a workpiece with a small machining allowance is ground at a large dimensional change rate, that is, at a high speed, and the grinding accuracy is not reduced by that amount. The cycle time will be shortened.

〔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 driving device 7, a work driving device 14, and a grindstone dressing device 15.

The grindstone table 2 of the grindstone driving device 7 is placed on the upper surface of the bed 1a so as to be slidable 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 A ball screw 3 is screwed, and a 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 the bed 1
A work table moving ball screw 9 is screwed into a female screw box (not shown) fixedly mounted on the lower surface of the work table 8 on the upper surface of a so as to be slidable in the vertical direction in the figure. The cutting feed motor 10 to which the output shaft is connected 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 near the headstock 11 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.

20 is a cutting control device, which is fast-forward, semi-fast-forward,
In the black skin grinding, the cutting speed and the cutting amount signal from the pulse encoder 28 are received, and the cutting speed of the grinding device 1 is
This is for feedback control so that the depth of cut becomes a set value, and in rough grinding and finish grinding, a detection signal of the in-process gauge 60 is received and the dimensional change rate of the work W becomes a set 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 dimensional change rate setting unit that sets a rough dimensional change rate Rd ₀ and a finish dimensional change rate Fd ₀ according to the type of work, 22 is a semi-rapid feed amount, a black skin grinding amount, a rough grinding amount, and a finish grinding amount. This is a cutting amount setting unit that sets the size according to the type of
It is determined based on the work (difference between the average value of the unprocessed diameter and the finished processed diameter). For example, the rough dimension change rate Rd
₀ is set in advance by experiments or the like so that the average machining allowance S can be machined with a predetermined accuracy, and this is a rough dimensional change rate with respect to the average machining allowance. Two
Denoted at 3, 24, and 32 are a cutting speed setting value, a cutting amount setting value, and a dimensional change rate setting value, respectively, which are selected in accordance with a selection signal E from the selection signal creating section 25. Section, the dimensional change rate selection section, and the selection signal E is generated according to the sequence signal F from the sequence control section 26. Reference numeral 27 denotes a drive control signal creation unit, which sets the setting values selected by the cutting speed selection unit 23 and the cutting amount selection unit 24 as target values, the rotation speed of the cutting feed motor 10, A drive control signal C for comparing the current value from the pulse encoder 28 for detecting the rotation amount and feedback-controlling the cutting feed motor 10 so that they match each other.
Create and output.

Reference numeral 35 denotes a current dimensional change rate calculation unit for receiving a detection signal from the in-process gauge 60 and calculating a current dimensional change rate ΔD = dD / dt of the machining inner diameter of the work W when the clock t is input, and 33 is a dimensional change. Is a rate control signal generator,
This receives the current dimensional change rate ΔD from the present dimensional change rate calculating section 35 and the dimensional change rate set value from the dimensional change rate selecting section 32, and outputs a dimensional change rate control signal C ′ according to the difference between the two values. Create and output. Further, 34 is a changeover switch for selectively passing the dimension change rate control signal C'and the drive control signal C according to the selection signal E, and 29 is a drive according to the drive control signal C or the dimension change rate control signal C '. The driver outputs the signal D.

Reference numeral 30 is a gap eliminator that detects the contact of the grindstone 6 with the surface to be processed of the work W from the change in the electric power of the wheel head motor 5. This is because the inner diameter of the work W at the start of grinding, that is, the unprocessed inner diameter Ds is detected. Has become a work sensor.

Reference numeral 40 denotes a stock removal computing device for computing the increase / decrease amount B of the stock removal B ′ of the work W with respect to the average stock removal S.
1 and a stock removal amount increase / decrease calculation unit 42. The machining allowance calculation unit 41 receives a contact detection signal between the grindstone 6 and the work W from the gap eliminator 30, receives an unprocessed inner diameter Ds obtained from the cutting feed position at the time of detection, and a preset finishing inner diameter Df. Then, the stock removal B'of the work W is calculated by the following equation (1).

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

Reference numeral 50 denotes a dimensional change rate correction device, which is a set rough dimensional change rate Rd for the workpiece of the average machining allowance S set above.
_This is for correcting ₀ to the actual rough dimension change rate Pd according to the stock removal increase / decrease amount B by the following equation (2).

Rd = Rd ₀ −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 dimension change rate Rd.
Corresponding to the proportional coefficient K in (2), this is an experimental value determined by the type of work, that is, the material, size or pre-processing, for example, the degree of heat treatment. As is clear from the figure,
For a workpiece with a stock removal increase / decrease amount B of 0, that is, an average stock removal S, the actual rough dimension change rate Rd is Rd _0, which is the same as the set value, and B ₁ , B
The _second workpiece is _Rd 1, Rd _2, is smaller the larger the allowance.

In the apparatus of this embodiment, various cutting speeds, cutting amounts, and dimensional change rates are set by the setting units 21, 22, and 31.
When the work W is loaded on the headstock 11 and the present apparatus is started, the sequence signal F is input from the sequence control unit 26 to the selection signal creation unit 25, and the selection signal E for selecting the semi-rapid feed is turned off from the creation unit 25. It is input to the cutting speed selection unit 23, the cutting amount selection unit 24, the dimensional change rate selection unit 32, and the changeover switch 34. Then, first, both the selection units 2
In 3 and 24, the set quasi-rapid feed speed and the set quasi-rapid feed amount, which are the target values, are selected, and the changeover switch 34 is switched to the drive control signal generating section 27 side. In this case, there is no selection output from the dimension change rate selection unit 32. Then, both of the selected target values are compared with the current value input from the pulse encoder 28 in the drive control signal creating unit 27,
A drive control signal C corresponding to the difference between the two is generated, the control signal C is input to the driver 29 via the changeover switch 34, and the drive signal D corresponding to the control signal C is input to the cutting feed motor 10. As a result, the work W is fed in the direction perpendicular to the axis. In addition, the cutting speed and the cutting amount at this time are fed back to the drive control signal generating unit 27 via the pulse encoder 28, and in this way, the cutting speed and the feed amount are controlled to a predetermined set cutting speed and feeding amount.

Then, in the above-mentioned semi-rapid feed, the inner surface of the work W is the grindstone
When touching, the target value and the current value match, and this matching signal G is input to the selection signal creating unit 25,
A signal E for selecting the black skin cutting speed and the black skin grinding amount is input from the creating unit 25 to the respective selecting units 23 and 24, and the black skin grinding is performed in the same manner as described above. When the black skin grinding is completed, the selection signal E becomes a signal for selecting the rough grinding. Therefore, the dimensional change rate selecting section 32 selects the dimensional change rate, and the changeover switch 34 is switched to the dimensional change rate creating section 33 side. .

Further, the gap eliminator 30 detects the contact between the work W and the grindstone 6 in the semi-rapid feed from the electric power change of the wheel head motor 5 at this time, and this detection signal is input to the stock removal calculation unit 41. Considering a work in which the stock removal B ′ is larger than the average stock removal S by B ₁ , the stock removal calculation unit 41 described above is used.
In the above formula (1) by machining allowance B 'are calculated, further decrease amount with respect to the average stock removal S, this case is calculated is increased or decreased amount of B _1, the allowance bulking B ₁ represents the dimensional change rate correcting unit 50
Entered in. Then, in the device 50, the set rough dimension change rate Rd ₀ is corrected to the actual rough dimension change rate Rd ₁ according to the stock removal increase amount B ₁ by the equation (2), and the dimension change rate Rd
d ₁ is input to the dimension change rate selection unit 32. As described above, since the rough grinding selection signal E is input to the selection unit 32, the actual rough dimension change rate Rd ₁ is input to the dimension change rate control signal creation unit 33, where the actual rough dimension change is performed. Rate R
A dimensional change rate control signal C'corresponding to the difference between d ₁ and the current dimensional change rate ΔD from the current dimensional change rate calculator 35 is generated, and the control signal C'is sent to the driver 29 via the changeover switch 34. The drive signal D that is input and corresponds to the control signal C '
Thus, the cutting feed motor 10 is drive-controlled, and thus the cutting control is performed so that the dimensional change rate of the workpiece W becomes the actual rough dimensional change rate Rd ₁ corresponding to the stock removal increase amount B ₁ .

Further, when the rough grinding is completed, next, finish grinding is also performed by the constant dimensional change rate control. In this case,
The cutting control is performed with the set finishing dimension change rate Fd ₀ target value set based on the work of the average machining allowance S. In this way, in this embodiment, the black skin grinding is performed by the constant speed control and the rough grinding is performed. , And finish grinding, the cutting speed is controlled by the constant dimensional change rate control.

As described above, in this embodiment, since the stock removal of the work W is obtained and the cutting stock is controlled by the actual rough dimension change rate which is smaller as the stock removal corresponding to the size of the stock is larger, the stock removal is increased. Also reduces grindstone damage and maintains the sharpness of the grindstone.As a result, the grindstone life can be extended and grinding accuracy can be improved.Conversely, a workpiece with a small machining allowance can be ground at a large dimensional change rate, so cycle Time can be shortened.

Although the gap eliminator 30 has been described as an example of the work sensor in the above embodiment, 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 it after loading. Further, in the above embodiment, only the rough dimensional change rate is corrected in accordance with the stock removal, but the dimensional change rate of black skin grinding may be further corrected. 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, the work allowance is determined, and the dimensional change rate is controlled according to the allowance. It has the effect of extending the life and improving 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 dimension change rate characteristic chart. DESCRIPTION OF SYMBOLS 1 ... Grinding device, 20 ... Depth control device, 30 ... Gap eliminator (work sensor), 40 ... Margin calculation device, 50 ... Dimensional change rate correction device, 61 ... Depth control means, 62 ... … Work sensor, 63 …… Allocation calculation means,
64: Dimensional change rate correction means.

Claims (1)

[Claims] 1. A grinding device for performing grinding on an inner surface or an outer surface of a workpiece, a detection means for detecting an inner diameter or an outer diameter of the workpiece by an in-process, and a cutting speed of the grinding device for a dimensional change rate. While controlling so that it becomes constant in each grinding process, the cutting control means for calculating the current dimensional change rate by receiving the output of the detection means and creating the dimensional change rate control signal, and the inner or outer diameter of the workpiece. A work sensor that detects the diameter, a machining allowance calculation unit that calculates the machining allowance that is the machining allowance of the workpiece from the detection output of the work sensor, and the difference between the average value of the unmachined diameters of multiple workpieces and the finished machining diameter. For a certain average
The machining allowance calculation means, which comprises a machining allowance increase / decrease calculation unit for calculating the machining allowance increase / decrease, and a dimensional change rate that is an optimum value for the work having the average machining allowance are preset, and the machining allowance increase / decrease is A grinding control device comprising: a dimensional change rate correcting means for giving a dimensional change rate correction signal for making the dimensional change rate smaller than the set dimensional change rate for the average machining allowance to the cutting control means as the value is larger.