JPS61252064A - Device for controlling grinding - Google Patents

Abstract

PURPOSE:To grind a workpiece with a swivel quantity corresponding to a machining allowance or the deflecting angle of a wheel spindle and prevent a machined surface from becoming a tapered condition by obtaining the machining allowance of said workpiece and providing a control means for controlling the swivel quantity corresponding to said machining allowance. CONSTITUTION:The inside diameter or outside diameter of a workpiece is detected by a work sensor 62, and the machining allowance, or the machining part of the workpiece, is operated from the detected output by a machining allowance operating means 63. The greater the operated machining allowance is, the greater a swivel quantity which is the intersecting angle between the main spindle of a grinding device 1 and a wheel spindle, is made by a swivel correcting signal, which is given to a swivel control means 61 through a swivel quantity correcting means 64. Based on this swivel correcting signal, a workpiece with a large machining allowance can be ground by means of a grinding device 1 with a large swivel quantity corresponding to the size of the deflecting angle of the wheel spindle, to prevent a machined surface from becoming a tapered condition, while improving its cylindricality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a grinding control device that performs grinding while controlling a main spindle and a grindstone spindle to a predetermined swivel amount.

[Prior art]

Conventionally, when grinding the inner surface of a workpiece, for example, the grindstone is rotated and fed in the axial direction and inserted into the workpiece.
After that, the workpiece is fed with a cutting feed in the direction perpendicular to the axis, and the workpiece is pressed against a grindstone to sequentially perform black grinding, rough grinding, finish grinding, etc.

In this grinding process, it is inevitable that the grindstone shaft is bent by the pressure of the workpiece, and if this continues, the machined surface of the workpiece will become tapered and the cylindricity of the product will decrease. In order to suppress this taberization, a spark-out process is conventionally provided after the finish grinding process. It's not economical.

Conventionally, in grinding control devices, the main spindle and the grinding wheel spindle are adjusted to a specific intersecting state according to the expected deflection angle. For workpieces that have undergone different heat treatments in the previous process, the swivel amount is reset to a different amount for each type of workpiece, but for the same type of workpieces, the above deflection angle etc. are considered to be about the same, so The workpiece is also ground with a constant swivel amount. However, when grinding with the same swivel amount, the above-mentioned grinding accuracy, especially the cylindricity, may differ from work to work even for the same type of work.Therefore, with conventional grinding control devices, there is a problem that variations in grinding accuracy occur. On the other hand, in order to stabilize this cylindricity, it was necessary to lengthen the spark-out process, which resulted in a problem that the cycle time was extended. The reason why machining accuracy fluctuates in this way is that even if the workpiece is of the same type, the damage to the grinding wheel such as clogging changes depending on the grinding allowance, and the sharpness of the grinding wheel changes, and the bending angle of the grinding wheel axis changes accordingly. It is thought that the

[Purpose of the invention]

The present invention was made in view of such conventional problems, and
It is an object of the present invention to provide a grinding control device that can stabilize the cylindricity by eliminating taberization of a processed surface without increasing the cycle time.

[Structure and operation of the invention]

The present inventor has conducted extensive research into the causes of variations in cylindricity even for the same type of work in the above swivel control, and
We found the following points. That is, (a) In general, workpieces have variations in their unmachined diameters, and therefore the machining allowance, which is the difference between the unmachined diameter and the finished diameter, will vary between workpieces. In this case, the larger the machining allowance, the greater the damage to the grinding wheel such as clogging, the sharpness deteriorates, the deflection angle increases, and the machined surface becomes tapered.

(bl) Therefore, in order to achieve the above objective, it is necessary to find the machining allowance for each workpiece, and for workpieces with large machining allowances, it is necessary to grind with a large swivel amount corresponding to the large deflection angle. For the workpiece, the swivel amount can be reduced.

Therefore, the present invention provides a grinding control device that performs swivel control, as shown in the functional block diagram of FIG.
A grinding device 1 that performs grinding on a workpiece, a swivel fi control means 61 that controls the swivel amount of the device 1, and a workpiece sensor 62 that determines the machining allowance of the workpiece. A machining allowance calculation means 63 and a swivel amount correction means 64 for correcting the swivel amount by the swivel control means 61 are provided.

In the present invention having the above configuration, the machining allowance of the workpiece is determined by the workpiece sensor 62° and the machining allowance calculating means 63, and the swivel amount correction means 64 controls the swivel by controlling the swivel correction signal for increasing the swivel amount as the machining allowance becomes larger. As a result, a workpiece with a large machining allowance is ground with a large swivel amount corresponding to the deflection angle of the grinding wheel shaft, and as a result, even if the deflection angle becomes large according to the machining allowance, the workpiece is not taberized. As a result, the cylindricity is improved and stabilized, and the cylindrical time is shortened to the extent that the spark-out process is 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 configuration, 1 is a grinding device for grinding the inner surface of a workpiece W, and this is a grinding device. It is composed of a drive device 7, a workpiece drive device 14, and a grindstone dressing device 15.

The grindstone table 2 of the grindstone drive device 7 is placed on the top surface of the bed Ia so as to be slidable in the horizontal direction as shown in the figure, and a female screw box (not shown) fixed to the bottom surface of the grindstone table 2 is provided with a threaded box (not shown) for moving the grindstone table. A grindstone feed motor 4, to which a ball screw 3 is screwed and whose output shaft is connected to the ball screw 3, is mounted on the bed 1a. It is worn. Furthermore, a RAD motor 5 is attached to the wheel on the grindstone table 2,
A grindstone 6 is connected to the output shaft of the motor 5.

The work table 8 of the work drive device 14 has a bend 1
A ball screw 9 for moving the work table is screwed into a female screw box (not shown) fixed to the bottom surface of the work table 8. A cutting feed motor 1o to which its output shaft is connected is fixed to the bed la. On top of the workpiece 8 is a swivel table 8a.
is rotatably mounted, and the output shaft of a swivel motor 16 that rotationally drives the swivel table 8a is connected to the connection bracket portion 8b of the table 8a. Furthermore, a workpiece W is placed on the swivel table 8a.
A headstock 11 for chucking the headstock 11 is provided, 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 swinging type mounted on the work table 8, and a dressing tool 15b is attached to its swinging arm 15a.

Reference numeral 60 denotes a cutting control device, which performs feedback control of the cutting speed and cutting feed amount by the cutting feed motor 10 of the grinding device 1 so that they become set values.

A swivel control device 20 receives a swivel amount signal from the swivel motor 16 via a pulse encoder 28 and performs feedback control so that the swivel amount of the grinding device 1 becomes a predetermined value. In FIG. 3 showing the block configuration of this swivel control device 20, etc., 21 is a swivel angle setting section, and in this setting section 21, a set swivel amount θO that does not cause taper in a work with an average machining allowance S is set. This was determined in advance through experiments. Reference numeral 22 denotes a drive control signal generation unit, which compares the set swivel amount as a target value with the current swivel amount of the swivel motor 16 inputted via the pulse encoder 28, and determines that the two match. A drive control signal C for feedback controlling the swivel motor 16 is created. And 23
is a driver that creates a drive signal corresponding to the drive control signal C described above.

30 is a gap eliminator that detects when the grinding wheel 6 contacts the processed surface of the workpiece W from the power change of the rad motor 5 to the wheel; It has become.

Reference numeral 40 denotes a machining allowance calculation device that calculates an increase/decrease B in the machining allowance B° of the workpiece W with respect to the average machining allowance S;
1 and a machining allowance increase/decrease calculation section 42. The machining allowance calculation section 41 receives a contact detection signal between the grinding wheel 6 and the workpiece W from the gap eliminator 30, and calculates the raw inner diameter Ds at the start of grinding determined from the cutting feed position at the time of cough detection and a preset value. From the finished inner diameter Df, use the following formula (1)
The machining allowance B' of the workpiece W is calculated.

B' = (Df-Ds)/2...
(1) Further, the machining allowance increase/decrease calculating section 42 calculates the increase/decrease B-3-B' of the machining allowance B° with respect to the average machining allowance S.

Reference numeral 50 denotes a swivel amount correction device, which adjusts the set swivel amount θ0 for the workpiece of the average machining allowance S set in the swivel angle setting unit 21 by using the following formula (2) to calculate the actual swivel amount according to the increase/decrease B of the machining allowance. Convert to θ.

θ=θo+ *B...(2)
Next, the effects will be explained.

Here, FIG. 4 is a characteristic diagram showing the relationship between the actual swivel amount θ and the change in removal amount B, and the slope of the characteristic line is expressed by the above equation (2).
This corresponds to the proportionality constant K, which is an experimental value determined by the type of workpiece, that is, the material, size, or the degree of preprocessing, such as heat treatment.

As is clear from the figure, when the machining allowance increase/decrease is 0, that is, the average machining allowance S, the actual swivel amount θ is the same as the set value θ0, and B1. When B2, θ1. θ2, and the larger the machining allowance, the larger the swivel amount.

First, to explain the depth of cut control in this device, when the workpiece W is loaded onto the headstock 11 and the device is started, the depth of cut control device 60 sets the cutting feed rate in advance, as in the conventional system. The cutting feed motor 10 is feedback-controlled so that the cutting feed amount becomes , and the cutting feed amount, thereby sequentially performing black scale grinding, rough grinding, finish grinding, and spark out.

Next, swivel control for a workpiece whose machining allowance B' is larger than the average machining allowance S by B1 will be explained.

In the above-mentioned cutting control, when the inner surface of the workpiece W contacts the grindstone 6, the gear tooth eliminator 30 detects the contact between the two from the change in the power of the grinding motor 5 to the wheel at the time of this contact, and this detection signal is sent to the machining allowance calculation section. 41. Then, the machining allowance calculation unit 41 calculates the machining allowance B° using the above formula (1), and furthermore, the machining allowance increase/decrease calculation unit 42
The machining allowance increase B1 is calculated in , and this machining allowance increase 31B is input to the swivel amount correction device 50. In this swivel amount correction device 50, the set swivel amount θ0 is determined by the actual swivel amount θ according to the machining allowance increase B1 according to the above formula (2).
The signal is corrected to 1 (see FIG. 4), and is input to the drive control signal generator 22.

In the drive control signal generation section 22, the actual swivel amount θ1
is set as a target value, this value is compared with the current value from the pulse encoder 28, and a drive control signal C is created to make the two coincide. This control signal C is input to the driver 23, and a drive signal corresponding to the control signal C is input to the swivel motor 16, so that the axis of the headstock 11 is moved counterclockwise with respect to the axis of the grinding wheel 6. Swivel control is performed to rotate by θ1, and the above-mentioned depth of cut control is performed using this swivel amount θ1. As a result, the workpiece W is ground to the same finishing inner diameter over the entire length of the machined surface, ensuring a predetermined cylindricity. Ru.

In this way, in this embodiment, the set swivel amount θO for the average machining allowance S is corrected to the actual swivel amount θ corresponding to the increase/decrease i1B in machining allowance, and swivel control is performed using this as the target value, so that the size of the machining allowance can be adjusted. In addition, grinding can be performed with a swivel amount that corresponds to the deflection angle of the grinding wheel shaft.
As a result, the same type of workpiece can be ground to the same cylindricity even if the machining allowance is different, improving the cylindricity and stabilizing it.Moreover, in this case, there is no need to lengthen the spark-out process, so the cycle time is extended. It's never done.

In the above embodiment, the gap eliminator 30 is used as an example of the workpiece sensor, but the workpiece sensor may be, for example, a bridgeage that measures the inner diameter of the workpiece before loading, or an in-process gauge that measures the inner diameter of the workpiece after loading. In the example, a case has been described in which the inner surface of the workpiece is ground, but the present invention can of course also be applied to grinding the outer surface.

〔Effect of the invention〕

As described above, according to the grinding control device according to the present invention, the machining allowance of the workpiece is determined and the swivel amount is controlled according to this machining allowance, so that the swivel amount is controlled according to the machining allowance and the deflection angle of the grinding wheel shaft. It has the effect of being able to grind, prevent tapering of the processed surface, improve cylindricity, and stabilize it.

[Brief explanation 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 a block diagram thereof, and FIG. 4 is an increase/decrease in machining allowance. −
It is an actual swivel amount characteristic diagram. l...Grinding device, 20...Swivel control device, 30
...Gap eliminator (work sensor), 40.
...Machining allowance calculation device, 50...Swivel amount correction device, 6
1...-Swivel control means, 62... Work sensor,
63...Machining allowance calculation means, 64...Swivel amount correction means.

Claims (1)

[Claims] (1) A grinding device that grinds the inner or outer surface of a workpiece, a swivel control means that controls the amount of swivel that is the intersection angle between the main axis of the grinding device and the grindstone axis, and A workpiece sensor that detects the diameter, a machining allowance calculation means that calculates a machining allowance, which is a machining allowance of the workpiece, from the detection output of the sensor, and a swivel correction that increases the swivel amount as the machining allowance from the machining allowance calculation means increases. A grinding control device comprising: swivel amount correction means for applying a signal to the swivel control means.