JP2846938B2 - Workpiece rigidity calculation device for grinding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention is supported by a center mounted on a main shaft and a tailstock, and by feeding a grinding wheel to a workpiece rotating around the axis of the center. The present invention relates to a workpiece rigidity calculation device for calculating the rigidity of a workpiece in a grinding machine configured to grind a workpiece.

<Conventional technology> Conventionally, when grinding a workpiece with a grinder, the grinding wheel rotation speed,
It is necessary to determine the grinding conditions such as the rotation speed of the workpiece and the feed speed of the grinding wheel.

Among these grinding conditions, the wheel feed speed is determined in consideration of the amount of deflection of the workpiece, that is, rigidity. The invention disclosed in Japanese Patent Publication No. Hei 2-7790 discloses an apparatus for controlling the feed speed of a grindstone by calculating the rigidity.

<Problems to be Solved by the Invention> However, in the invention of the above-mentioned publication, the rigidity is calculated collectively for the entire workpiece. For this reason, in a workpiece having a plurality of grinding points, depending on the grinding points, the rigidity is actually larger than the calculated value, and the feed speed may be increased. . The rigidity of the workpiece is also affected by the rigidity of the supporting spindle and tailstock.

<Means for Solving the Problems> The present invention has been made to solve the problems described above, and has a shape input means for inputting shape data of a workpiece, and a support for storing rigidities of a main shaft and a tailstock shaft. Rigidity storage means, shape estimating means for estimating a cylindrical shape for each number of grinding steps of a workpiece from the shape data input by the shape input means, and cylindrical shape of the grinding step of the workpiece estimated by the shape estimating means A first deflection amount calculating means for calculating a deflection amount for each cylindrical shape; and a second deflection amount calculating means for calculating the deflection amount for each cylindrical shape from the rigidity of the main shaft and tailstock stored in the support rigidity storage means and the total length of the workpiece. And a stiffness calculating means for calculating a reciprocal obtained by adding the deflection amounts obtained by the first deflection amount calculating means and the second deflection amount calculating means to calculate the rigidity of the workpiece. .

<Operation> When shape data of a workpiece is input by the shape input unit, the shape estimating unit estimates a cylindrical shape for each number of grinding stages of the workpiece based on the shape data. A deflection amount for each cylindrical shape is calculated from the estimated cylindrical shape by the first deflection amount calculation means, and a first deflection amount is calculated from the rigidity of the main shaft and the tailstock stored in the support rigidity storage means and the total length of the workpiece. (2) The deflection amount calculating means calculates the deflection amount in consideration of the support stiffness, and the stiffness calculation means calculates the reciprocal obtained by adding the deflection amounts obtained by the first deflection amount calculating device and the second deflection amount calculating device. The rigidity is calculated for each cylindrical shape.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings. First
In the figure, reference numeral 10 denotes a main body of a grinding machine. A workpiece W is supported at both ends by a center between a headstock 13 and a tailstock 14 mounted on a bed 111 via a table 12, and a spindle motor 15 is provided. The main shaft 13a is driven by the rotation of the main shaft 13a. A grinding wheel head that supports a grinding wheel 16
17 is guided on the bed 11 so as to be able to advance and retreat with respect to the processing surface of the workpiece W, and is moved by a servomotor 18.

On the other hand, reference numeral 20 denotes a numerical controller for distributing pulses to a drive circuit 21 for driving the servomotor 18 to move the grinding wheel 16, and is mainly controlled by an arithmetic processing unit 22, a memory 23, a pulse generation circuit 25, and a gate circuit 26. It is configured. A rotation speed control circuit for rotating the spindle 13 at a speed corresponding to the command speed from the arithmetic processing device 22 is provided in the arithmetic processing device 22.
27 is connected via an interface 28, a numerical control program is stored in a memory 23, and a grinding condition calculation device (workpiece rigidity calculation device) is provided via an interface 31.
30 is connected.

As shown in FIG. 2, the grinding condition calculation device 30 includes a calculation processing device 35, a memory 32, a CRT display device 33, and a keyboard 34. The memory 31 stores a workpiece input from the keyboard 34. Workpiece data storage area PDA for storing shape data, workpiece material, required surface roughness, etc.
And a grinding condition storage area GTA in which the wheel feed speed and the workpiece peripheral speed are obtained and stored from the obtained rigidity value,
A characteristic data storage area CDA for storing characteristic data required for calculating the characteristics and rigidity of the grinding machine 10 and the grinding conditions is provided. In the characteristic data storage area CDA, as shown in FIG. 3, characteristic data indicating the relationship between the rigidity value and the grinding efficiency for each material of the workpiece and the characteristic data of the workpiece for each required surface roughness of the workpiece shown in FIG. The characteristic data indicating the relationship between the diameter and the peripheral speed of the spindle and the rigidity values of the spindles of the headstock 13 and the tailstock 14 of the grinding machine 10 are stored.

The operation of obtaining the stiffness value with the above configuration will be described with reference to the flowchart shown in FIG. 5 and FIG. First, in determining the stiffness value, the keyboard 34 is used to determine the axial dimension of a five-step shaped workpiece, the diameter of a cylindrical portion, the required surface roughness of a ground portion, and the material of the workpiece as shown in FIG. 6 (a). The data is input and stored in the work data storage area PDA. Then, it is determined in step 100 whether the shape data of the entire workpiece has been input.
Proceed to 104, and if not entered, proceed to Step 103. Here, in FIG. 6A, since the portions indicated by A2 and A4 in the five-step shape are non-ground portions, no diameter data has been input, so the process proceeds to step 103. In step 103, a process for estimating the shape of the portion where the shape data has not been input is performed. This process is a flowchart shown in FIG. The processing of the flowchart of FIG. 7 will be described with reference to FIG.

First, in step 200, the diameter d _(m) and d of the adjacent shapes A1 and A3 in the shape portion A2 whose diameter has not been input.
_{Read (m + 1)} from the work data storage area PDA
At 201, the diameter of the right side is compared with the diameter of the left side shape. If the diameter of the left side is large, the process proceeds to step 202; In this case, in the shape A2, the diameter d _(m) of the left shape A1 is smaller than that of the left shape A1, and the process proceeds to step 203.In step 203, the diameter of the shape A2 is set to the diameter d _(m) of the left shape A1. The axial dimension of the shape A1 that has not been input is obtained from the dimensions of the adjacent shapes A1 and A3. Then, in step 205, the axial dimension l of the left side shape A1
_The dimension obtained by adding the axial dimension lr _{(m + 1 )} of the shape A2 to _{r (m)} is the shape A
2 '. In the case of shape A4, the shape on the left side is set in step 202.
Since A3 is determined to be large, the process proceeds to step 202, where the diameter of the shape A4 is changed to the diameter d _{(m + 2) of the} right shape A5 in step 202.
And the shape A4 for which no dimensions have been entered in step 206
Is determined from the dimensions of the adjacent shapes A3 and A5.
Then, in step 207, the axial dimension l _{r (m + 4) of the} right side shape A5
Add the dimension A _r of the shape A4 to the axial dimension l _{r (m + 3).}
And As a result, the shape is estimated as shown in FIG. 6 (b), and the shape is determined. Here, the reason why the diameter is made smaller when estimating the shape is to make it possible to estimate that the amount of deflection of the part whose shape is unknown is large and the rigidity is small. The shaft dimension of this shape is the left end of the workpiece W.
Stored in coordinates with P _(m) as the origin. When the shape estimation is completed, the process proceeds to step 104, and the number of ground portions, that is, the number M of shapes is stored for the determined shape. In step 105, the parameter n for counting the number of stages is set to 1
Is set in step 106, and the load of the grindstone at the time of grinding the shape indicated by the parameter n is set as the concentrated load, and the coordinates of this load point are determined. This load point is determined assuming that a unit load is applied to the center of the shape. In the shape A1 'of FIG. 6 (b), the point of (P _(m) + P _{(m + 1)} ) / 2 is defined as the load point l. _{P (n)} . When the load point is determined, the process proceeds to step 107, where the deflection λ'n of the workpiece in the shape A1 'is Is calculated.

Next, proceeding to step 108, the headstock 13 and the tailstock 1 having the shape A1 '
The deflection λ ″ n considering the rigidity values a and b of the shaft 4 is Is calculated by E is the Young's modulus.

When the flexures λ'n, λ "n are calculated, the reciprocal of the value obtained by adding the flexures λ'n, λ" n is obtained in step 109 as the stiffness value K _{(n) of the} shape A1 '. , The process proceeds to step 110 to compare the number M of shapes with the parameter n,
It is determined whether the stiffness of all the shapes has been obtained. If the stiffness of all the shapes has been obtained, this program is terminated. If not, 1 is added to the parameter n in step 111 and the process returns to step 106.

By performing the above processing, the rigidity value and the shape data of the workpiece are stored in the workpiece data storage area PDA.

When the stiffness value is obtained, processing for determining the feed speed of the grindstone and the peripheral speed of the workpiece is performed. The feed speed of the grinding wheel is determined in the work data storage area PDA from the characteristic data indicating the relationship between the rigidity value for each material of the work and the grinding efficiency as shown in FIG. 3 and stored in the characteristic data storage means CDA. been workpiece material and grinding efficiency from the shapes each of rigidity value K _(n) for each shape Z _(n) is determined, the feed rate v of the shape grindstone by the following equation from the grinding efficiency Z _{(n) (n )} Is required.

The determination of the peripheral speed of the workpiece is based on the characteristic data indicating the relationship between the diameter of the workpiece and the peripheral speed of the spindle for each required surface roughness of the workpiece shown in FIG. The peripheral speed N of the workpiece is obtained from the diameter d _{(m) of the} shape and the required surface roughness, and is stored in the grinding condition storage area GTA.

After the grinding conditions are determined in this manner, the respective values are transferred to the numerical controller 20 and stored in the memory 23,
The stored peripheral speed N of the workpiece is determined by the spindle speed control circuit 27.
Is output to the main spindle rotation command.
13a is rotated. Then, when the feed speed v _{(n) of the} grinding wheel is output to the pulse generation circuit 25, the pulse generation circuit 25 starts pulse distribution, the servo motor 18 is driven, and the grinding wheel head 17 is moved at the speed v _(n) , Rough grinding of the workpiece is performed. Thereafter, the peripheral speed N of the workpiece and the feed speed v _{(n) of the} grindstone are finely ground at reduced values in accordance with the required surface roughness, whereby the grinding of one shape is completed. Grinding is performed in the same manner with respect to the shape, so that grinding according to the rigidity of each shape of the workpiece is performed.

<Effect of the Invention> As described above, in the present invention, the shape input means for inputting the shape data of the workpiece, the support rigidity storage means for storing the rigidity of the main shaft and the tailstock shaft, and the input by the shape input means Shape estimating means for estimating a cylindrical shape for each number of grinding steps of a workpiece from the obtained shape data, and a first deflection amount for calculating the amount of deflection for each cylindrical shape of the grinding step of the workpiece estimated by the shape estimating means Calculating means for calculating the amount of deflection for each cylindrical shape from the rigidity of the main shaft and tailstock stored in the support rigidity storing means and the cylindrical shape of the grinding stage of the workpiece estimated by the shape estimating means; Since there are provided second deflection amount calculating means, and rigidity calculating means for calculating a reciprocal obtained by adding the deflection amounts obtained by the first deflection amount calculating means and the second deflection amount calculating means to calculate the rigidity of the workpiece. , For each shape of the workpiece The amount of deflection can be obtained, and a rigidity value in consideration of the supporting rigidity can also be obtained, thereby providing an advantage that the grinding efficiency can be improved.

[Brief description of the drawings]

The drawings show an embodiment of the present invention. FIG. 1 is an overall configuration diagram of a grinding machine, FIG. 2 is a configuration diagram of a grinding condition calculation device, and FIG.
FIG. 4, FIG. 4 is a diagram showing characteristic data, FIG. 5, FIG. 7 is a flowchart showing processing of the arithmetic processing unit, and FIG. 6 is a diagram for explaining shape estimation. 10: Grinding machine, 13: Headstock, 13a: Spindle, 15: Spindle motor, 16: Grinding wheel, 17: Grinding wheel, 18: Servo motor, 20: Numerical controller, 22, 35 arithmetic processing unit, 23, 32 memories, 25 pulse generating circuit, 27 speed control circuit, 30 grinding condition arithmetic unit.

Continuation of the front page (56) References JP 27790 (JP, B2) JP 51-7779 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) B24B 49 / 16 B24B 47/20

Claims (1)

(57) [Claims] 1. A grinding machine which is supported by a center attached to a main shaft and a tailstock, and which grinds a workpiece by feeding a grinding wheel to a workpiece rotating about an axis of the center. A work rigidity calculating device,
Shape input means for inputting shape data of the workpiece, support rigidity storage means for storing rigidity of the main shaft and tailstock,
A shape estimating means for estimating a cylindrical shape for each grinding step number of the workpiece from the shape data input by the shape input means; and a deflection amount for each cylindrical shape of the grinding step of the workpiece estimated by the shape estimating means. First deflection amount calculating means for calculating, and second deflection amount calculating means for calculating the deflection amount for each cylindrical shape from the rigidity of the main shaft and tailstock stored in the support rigidity storage means and the total length of the workpiece. And a stiffness calculating means for calculating a reciprocal obtained by adding the deflection amounts obtained by the first deflection amount calculating means and the second deflection amount calculating means to calculate the rigidity of the workpiece. Workpiece rigidity calculation device