JP3300384B2 - Grinding machine control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling grinding conditions in a grinding machine.

[0002]

2. Description of the Related Art When performing a grinding process, grinding conditions are determined in advance in consideration of the material of a workpiece, the type of a grinding wheel, required accuracy, and the like. Reflecting the recent shortage of labor and skilled workers, technology development for automating the process of determining such grinding conditions is also being carried out. For example, JP-A-63-295
No. 177 discloses an automatic cutting speed determination method in which a grinding force is measured in inner surface grinding and a cutting speed is controlled so that the grinding force becomes constant.

[0003]

In the case where the grinding operation is continuous and the grinding force can be measured continuously, such as when plunge grinding is performed with an internal grinding machine or a cylindrical grinding machine, the cutting speed is reduced by the above-mentioned conventional technique. Can control. However, in the case of a surface grinding operation using a surface grinding machine, as shown in FIG. 7, the processing is intermittent and the cut is step-shaped, so that the grinding resistance is also generated intermittently. For this reason, it is not possible to control the depth of cut by continuously measuring the grinding resistance as in the above-described prior art. Normally, the fixed grinding wheel 6
However, the workpiece 13 moves, but in the figure, for convenience of explanation, the grinding wheel 6 is shown to move. By the way, if the substantial cutting amount in the surface grinding operation is always constant, the grinding force measured in the immediately preceding cutting step is compared with the allowable grinding resistance, and the cutting amount in the next cutting step can be determined based on the result. Even with a grinding machine, it is possible to control the grinding resistance constant as in the prior art.
However, as shown in FIG. 8, in the surface grinding, the cutting amount when the grinding wheel 6 and the workpiece 13 first contact each other generally includes an empty grinding, so that the initial substantial cutting amount is smaller than the set cutting amount. Therefore, the grinding force measured at this time is smaller than the value obtained when grinding with the regular set cutting amount, and when the next cutting amount is determined based on this grinding force, the cutting amount in the next cutting step becomes excessively large. There was a problem of becoming.

Further, the grinding force generally changes as shown in FIG. That is, if the initial depth of cut is excessive, the grinding resistance increases as shown by the dotted line a in the figure, and grinding burns and abnormal wear of the grinding wheel occur. Further, as shown by the dotted line b in the figure, if the initial cutting amount is too small, the efficiency becomes low. Therefore, as shown by the solid line c in the figure, it is important to determine the depth of cut so as to obtain an appropriate grinding force in terms of both accuracy and efficiency. Furthermore, in the cutting process in the so-called transient state several times after the start of grinding, even if the set cutting amount is constant, the uncut amount is generated due to the elastic displacement between the grinding wheel and the workpiece. Less than the amount. Then, as the actual number of cuts approaches the set amount of cut as the number of cuts increases, the grinding resistance gradually increases as shown in FIG. For this reason, when the next cutting amount is determined on the basis of the grinding resistance in the immediately preceding cutting process in the transient state, there is a problem that the cutting amount is also excessively large. An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a grinding machine control method capable of determining an appropriate cutting depth even when performing intermittent grinding such as surface grinding in a surface grinding machine. is there.

[0005]

In order to achieve the above-mentioned object, a first aspect of the present invention is to provide a workpiece with a predetermined cutting depth.
Infeed for grinding by relatively moving the grinding wheel and workpiece
Process is repeated intermittently until the workpiece is fixed size
A method of controlling a grinding machine in a grinding machine, wherein an allowable value of a physical detection amount that changes in accordance with the grinding resistance or the magnitude of the grinding resistance, and a detection in a cutting process that is successively performed.
An allowable range of the ratio of the amount is determined in advance, and the cut amount is kept constant until the ratio of the detected amount reaches the predetermined allowable range. When the detected amount exceeds the allowable value or the ratio of the detected amount is When the allowable range is reached, the ratio between the detection amount and the allowable value
Change the cutting amount in the next cutting process accordingly,
Detecting the amount of braking <br/> that Gyosu to be the limit for the subsequent cut process. In the second invention, a predetermined cut is made to the workpiece.
The grinding wheel and the workpiece are relatively moved by the
The cutting process to be performed is intermittently repeated until the workpiece
A method of controlling a grinding machine in a grinding machine to be turned back,
The allowable value of the grinding force or the physical detection amount that changes according to the magnitude of the grinding force is determined in advance, and the detection amount of the cutting process detected first is ignored, and the second and subsequent cuts are performed.
In the process, based on the detected amount in the current cutting process
Allowable grinding resistance as the depth of cut in the next
The amount of uncut and the amount of uncut in the current cutting process
Is controlled to be a value obtained by adding the difference between the current depth of cut and the current cutting depth .
The difference Δδ and the uncut amounts δs and δi are represented by the following equations 1 to 3. Δδ = δs−δi = (F0−Fi) / k Equation 1 δs = F0 / k Equation 2 δi = Fi / k Equation 3 where F0: allowable grinding resistance Fi: grinding resistance in each cutting process δs: allowable grinding resistance Uncut amount at F0 δi: Uncut amount at each cutting step k: Spring constant between grinding wheel and workpiece

[0006]

According to the first aspect of the present invention, as shown in FIG. 4, when the initial cutting amount is too small, the ratio of the grinding resistance in the cutting process before and after the cutting is compared, and the steady state where the ratio is smaller than a predetermined value is obtained. The depth of cut is constant until, but when it reaches a steady state, the depth of cut is increased as indicated by arrow B. On the other hand, if the initial depth of cut is excessive, the depth of cut is changed when the grinding resistance exceeds a preset allowable value. The depth of cut is changed in the direction to reduce the grinding resistance as shown in b. Therefore, even when the initial cutting amount is too large or too small, the cutting amount in the steady state is changed so that the grinding resistance becomes an appropriate value. Also, the second
In the invention, the difference Δδ between the uncut amount δi generated when the grinding resistance in each cutting step is Fi and the uncut amount δs when the allowable grinding resistance is F ₀ is calculated by adding a value obtained by adding the current cutting amount. Since the grinding is performed as a cutting amount in the next cutting step, as shown in FIG. 6, the allowable grinding resistance can be quickly reached. Further, in any of the methods, dressing is performed when the cut amount becomes equal to or less than the allowable value, so that accuracy and efficiency can be further improved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the configuration of an apparatus for carrying out the present invention will be described below with reference to FIGS. FIG. 1 is a side view showing a configuration example when the present invention is applied to a surface grinder.
Is a front view. 1 is a bed. 2 is a column, 1 bed
Are slidably held in the direction of arrow Y and are driven by the motor 3. Reference numeral 4 denotes a spindle head, which is slidably held on the column 2 in the direction of arrow Z and driven by a motor 5. Reference numeral 6 denotes a grinding wheel, which is attached to the tip of a grinding wheel shaft 7 rotatably held by the spindle head 4. 8
Is a table, which is slidably held on the bed 1 in the direction of arrow X and driven by a hydraulic cylinder (not shown). 9
Is a chuck attached to the table 8 via a force detector 10. The force detector 10 is connected to a numerical controller 12 via an amplifier 11. A workpiece 13 is mounted on the chuck 9. 14a, 14b
Is a proximity sensor attached to the bed 1. Fifteen
Is a dog attached to the table 8. In addition,
When the dog 15 faces the proximity sensors 14a and 14b,
At the same time as the signals from the proximity sensors 14a and 14b are input to the numerical controller 12, the moving direction of the table 8 is switched. The operation will be described below, taking as an example a case where the workpiece 13 is machined by plunge grinding with cuts at both ends. FIG. 3 is a flowchart of the cutting amount control according to the first embodiment of the present invention. Hereinafter, steps 110 to 200 in FIG. 3 are collectively referred to as “transient state control”.
Call. Steps 300 to 360 are collectively referred to as “steady state control”. The motor 3, the motor 5, and the hydraulic cylinder (not shown) are controlled by a program previously input to the numerical controller 12, and the workpiece 9 is moved to the grinding wheel 6.
It is processed by. Here, the grinding resistance is determined by the proximity sensor 1
4a as a trigger and the proximity sensor 14b
, And only the grinding resistance in the up-cut grinding is measured. The grinding wheel 6 descends at a rapid traverse to the vicinity of the workpiece 13, and thereafter, when receiving signals from the proximity sensors 14 a, 14 b, the grinding wheel 6 descends by the cutting amount t to perform grinding. At the same time, the grinding force F is reduced by the force detector 10. Measured (step 1
20). In the cutting step where the grinding force F is measured first, the cut amount is not changed, and the process proceeds to the next cutting step. However, if the grinding resistance F is larger than the allowable grinding resistance F ₀ , the process proceeds to a “steady state control” process described later (step 150). It measured grinding force Fi to the second and subsequent first be compared with the permissible grinding force F _0, moves to "control the steady state" to be described later to be larger than the permissible grinding force F ₀ (step 190). When the measured grinding resistance Fi is smaller than the allowable grinding resistance F ₀ , the ratio with the grinding resistance F _i−1 of the immediately preceding cutting step is calculated, and while this ratio is larger than the allowable value α, the cutting amount is reduced. No change is made and grinding continues (step 200). And F
When i / F _i-1 ≤ α, the process proceeds to the “steady state control” step, where the depth of cut is changed to (F ₀ / Fi) · t by the ratio of the grinding resistance Fi to the allowable grinding resistance F _0. (Step 300)
Grinding is performed, and this operation is continued until a fixed size is reached, and the grinding is completed. If the cutting amount becomes smaller than the allowable value β in the middle (step 310), it is determined that the sharpness of the grinding wheel 6 has deteriorated, and dressing is performed (step 320). In the present embodiment, the above configuration is adopted. As shown in FIG. 4, when the initial cutting amount is small, the cutting amount is constant in the transient state, but the cutting amount is changed after the steady state and the predetermined amount is changed. The grinding is performed under the grinding resistance F ₀ . If the initial depth of cut is large, the depth of cut is changed immediately when the grinding resistance Fi exceeds the allowable grinding resistance F ₀ even in a transient state, and the allowable grinding resistance F
Since it is controlled to be ₀ , the cutting amount is not excessively changed, and there is an effect that grinding burn and abnormal wear of the grinding wheel are prevented. In addition, since the sharpness of the grinding wheel is restored by dressing when the depth of cut is equal to or less than the allowable value β, the grinding can not be continued with an excessively small depth of cut and efficient grinding can be performed. effective.

FIG. 5 is a flowchart showing a second embodiment of the present invention. Note that the steps up to the first measurement of the grinding resistance are the same as those in the above embodiment, and will not be described. 2
The grinding force F measured after the first time is compared with the allowable grinding force F _0, and the next cutting amount, that is, the cutting amount after the third time is changed to t + (F ₀ −F) / k, and the next cutting is performed. Will be Hereinafter, this operation is repeated until the fixed size is reached. If the cutting amount becomes smaller than the allowable value β in the middle, it is determined that the sharpness of the grinding wheel has deteriorated, and dressing is performed. In the present embodiment, the above configuration is adopted.
As shown in (1), the cut amount is changed in consideration of the uncut amount, and a steady state is obtained in a short time after the start of the cut. Therefore, in addition to the effects of the above-described first embodiment, efficient machining can be performed. There is an effect that can be.

In the above two embodiments, since the grinding resistance generally differs between the up-cut grinding and the down-cut grinding, the control is performed only by the grinding resistance in the up-cut grinding. However, the allowable grinding resistance is provided separately. Accordingly, the control may be performed with both the grinding resistance of the up-cut grinding and the down-cut grinding, or may be controlled only with the grinding resistance of the down-cut grinding. Also, in the above two embodiments, the case of plunge grinding with both ends cut was shown. However, the case of single end cut can be controlled in the same manner, and in the case of traverse grinding, it is possible to use the grinding resistance for each traverse step. Similar control can be performed. Further, in both of the above embodiments, the grinding resistance is used as the detection amount, but a physical amount corresponding to the grinding resistance, such as a change in motor current caused by the grinding resistance, a change in elastic displacement or vibration of each part, may be used as the detection amount. .

[0010]

As described in detail above, according to the present invention,
Even when performing intermittent grinding like surface grinding in a surface grinder, it is possible to determine an appropriate depth of cut, which prevents the depth of cut from becoming severe and causing grinding burns and abnormal wear of the grinding wheel, Even if the initial cut is too large or too small, the optimum cut amount can be set. That is, since the optimal cut amount can be automatically set, there is an effect that accuracy and work efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a side view of a surface grinding machine showing a configuration example when the present invention is applied.

FIG. 2 is a front view of a surface grinding machine showing a configuration example when the present invention is applied.

FIG. 3 is a flowchart showing a control method according to the first invention.

FIG. 4 is an explanatory diagram showing a relationship between the number of cutting steps, a grinding resistance, and a cutting amount in the first invention.

FIG. 5 is a flowchart showing a control method according to the second invention.

FIG. 6 is an explanatory diagram showing a relationship between the number of cutting steps, a grinding resistance, and a cutting amount in the second invention.

FIG. 7 is an explanatory view showing a relative movement mode between a grinding wheel and a workpiece in the surface grinding machine.

FIG. 8 is an explanatory view showing a relative movement mode between a grinding wheel and a workpiece in the surface grinding machine.

FIG. 9 is an explanatory view showing a relative movement mode between a grinding wheel and a workpiece in the surface grinding machine.

[Explanation of symbols]

 6 Grinding wheel 10 Force detector 12 Numerical controller 13 Workpiece 14a, 14b Proximity sensor 15 Dog

Claims (2)

(57) [Claims] 1. A grinding wheel having a predetermined cutting depth with respect to a workpiece.
Cutting process to perform relative grinding of workpiece and workpiece
For a grinder that repeats intermittently until the workpiece becomes a fixed size
A method of controlling a grinding machine in which the allowable value of a physical detection amount that changes in accordance with the grinding resistance or the magnitude of the grinding resistance, and the allowable range of the ratio of the detection amount in the cutting process that follows one after another. The depth of cut is kept constant until the ratio of the detection amount is within a predetermined allowable range, and the cut amount is greater than the allowable value, or when the ratio of the detection amount is within the allowable range, Detection amount and tolerance
Change the cutting depth in the next cutting process according to the value ratio
And the detected amount in the next and subsequent cutting process becomes an allowable value.
Grinder control wherein the benzalkonium be so that control. 2. A grinding wheel having a predetermined cutting depth with respect to a workpiece.
Cutting process to perform relative grinding of workpiece and workpiece
For a grinder that repeats intermittently until the workpiece becomes a fixed size
A method of controlling a grinding machine in which the allowable value of the grinding force or the physical detection amount that changes in accordance with the magnitude of the grinding force is set in advance, and the detection amount of the cutting process detected first is ignored. And the second and subsequent cuts
In the process, based on the detected amount in the current cutting process
Allowable grinding resistance as the depth of cut in the next
The amount of uncut and the amount of uncut in the current cutting process
A control method for controlling the difference so as to obtain a value obtained by adding the difference to the current depth of cut .