JP3351229B2 - Non-circular grinding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-circular grinding device for grinding a non-circular workpiece such as a cam while rotating its outer peripheral surface with a rotary grindstone.
More particularly, the present invention relates to an apparatus for controlling a rotation speed of a spindle on which a workpiece is mounted.

[0002]

2. Description of the Related Art Heretofore, as an apparatus for rotating a main spindle on which a workpiece is mounted and relatively moving a rotary grindstone in a direction perpendicular to the main axis to grind the outer periphery of the workpiece into a non-circular shape. For example, a cam grinder for grinding a cam in a vehicle engine is known.

In this type of cam grinder, profile data in which a relationship between a rotation angle of a spindle and a moving position of a rotary grindstone is stored in advance in a numerical control device (hereinafter referred to as an NC device) as control data. I have. Then, based on the profile data, the moving position of the rotary grindstone is controlled by the NC device in accordance with the rotation angle of the main spindle, so that the workpiece is ground at a predetermined cutting amount set in advance, and the non-true A cam as a circular body is formed.

[0004]

As shown in FIG.
The workpiece Wa is cut into a predetermined cutting amount by the rotating grindstone 12.
When grinding with H, the workpiece Wa and the rotary grindstone 12
Grinding force acts on However, since the cam has a non-circular shape, the contact length Li (see FIG. 18) of the rotary grindstone 12 with the workpiece Wa with the rotation of the workpiece Wa.
(Shown by a bold line) changes. The change in the contact length Li during the grinding process appears as a change in the frictional resistance of the grinding resistance. Then, since the frictional resistance becomes large in the portion where the contact length Li is large, there is a problem that the finished surface of the workpiece Wa is thermally damaged and the processing quality such as grinding burns and grinding cracks is reduced. there were.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to suppress an increase in frictional resistance at the time of grinding to prevent a decrease in the processing quality. An object of the present invention is to provide a grinding device for a perfect circular body.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a rotating means for rotating a spindle on which a workpiece is mounted, and a rotary grinding wheel for grinding an outer peripheral surface of the workpiece. Moving means for relatively moving the main axis in a direction intersecting with the main axis, and controlling the moving means based on control data which sets a relationship between a rotation angle of the main axis and a moving position of the rotary grindstone while rotating the main axis. Then, in a non-circular body grinding device for grinding the workpiece into a predetermined non-round shape, the workpiece and the rotary grindstone with respect to the workpiece angle based on the cutting amount of the rotary grindstone with respect to the workpiece First calculating means for calculating a contact length, and a main shaft rotation with respect to a main shaft rotation angle based on a reference main shaft rotation speed set in advance corresponding to a non-circular base circular portion and the calculated contact length. Second to calculate speed Calculating means, third calculating means for calculating a moving position of the rotary grindstone with respect to time change based on the calculated spindle rotational speed and the control data, and rotating with respect to time change based on the calculated moving position. Fourth calculating means for calculating the moving acceleration of the grindstone, determining means for determining whether the calculated moving acceleration is within a predetermined value, and determining the moving acceleration based on the result of the determination. If any of the values exceeds the reference value, the reference rotation speed is corrected so as to be reduced, and the reference spindle rotation speed correction means for causing the second calculation means to the fourth calculation means to perform the calculation again. When the moving acceleration is within a specified value, the main spindle rotation speed is determined based on the latest reference main spindle rotation speed and the latest main spindle rotation speed based on the latest main spindle rotation angle. Rotation control data determination means, comprising a control means for controlling the rotation means based on the spindle rotation control data determined during the grinding process, the rotation speed of the spindle is determined by the contact length between the workpiece and the rotary grindstone The rotation speed of the main spindle is set so that the rotation speed changes in accordance with the rotation speed and the accompanying movement acceleration of the grinding wheel falls within a specified value.

According to a second aspect of the present invention, in the first aspect,
The second calculating means calculates the spindle rotation speed such that ω changes in proportion to 1 / L when the contact length between the workpiece and the rotary grindstone is L and the spindle rotation speed is ω. Configuration.

According to a third aspect of the present invention, in the first or second aspect, the second calculating means has means for calculating a contact length with respect to the main shaft rotation angle from a calculation result by the first calculating means. .

According to a fourth aspect of the present invention, in the first or second aspect, the second calculating means has means for calculating a main shaft rotation speed with respect to a workpiece angle from a calculation result by the first calculating means. I have.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the reference main spindle rotational speed correcting means includes:
There is provided a means for calculating a correction amount of the reference spindle rotational speed in accordance with a difference between the maximum value of the moving acceleration of the rotary grindstone and the specified value.

According to a sixth aspect of the present invention, there is provided a rotating means for rotating a spindle on which a workpiece is mounted, and a moving means for relatively moving a rotary grindstone for grinding an outer peripheral surface of the workpiece in a direction intersecting the spindle. While rotating the main shaft, the moving means is controlled based on control data that sets the relationship between the rotation angle of the main shaft and the moving position of the rotary grindstone to grind the workpiece into a predetermined non-circular shape. A first calculating means for calculating a contact length between the workpiece and the rotary grindstone with respect to the workpiece angle based on a cutting amount of the rotary grindstone with respect to the workpiece, Second calculating means for calculating a main shaft rotation speed with respect to the main shaft rotation angle based on a reference main shaft rotation speed set in advance corresponding to the circular base circular portion and the calculated contact length; Based on spindle speed A rotation speed change amount calculating means for calculating a rotation speed change amount between main shaft unit rotation angles with respect to the main shaft rotation angle, and a determination means for determining whether the calculated rotation speed change amount is within a predetermined range or not. As a result of the determination, when there is a rotation speed change amount exceeding a specified range, the minimum rotation speed width in the non-circular lift portion is increased with respect to the main shaft rotation speed by the second calculation means. Spindle rotation speed correcting means for correcting the main shaft rotation speed, and determining the main shaft rotation speed and the reference main shaft rotation speed for the corrected main shaft rotation angle as main shaft rotation control data, or rotating based on the result of the determination. When the speed change amount is within the specified range, the main shaft rotation speed and the reference main shaft rotation speed with respect to the main shaft rotation angle by the second calculating means are used as main shaft rotation control data. Spindle rotation control data determining means for determining, and control means for controlling the rotating means based on the determined spindle rotation control data at the time of grinding, the rotation speed of the spindle is the contact between the workpiece and the rotary grindstone The main shaft rotation speed is set so as to change in accordance with the length and to reduce data in a portion where the rotation speed change amount between the unit rotation angles is large.

According to a seventh aspect of the present invention, in the sixth aspect,
The second calculating means is configured such that, when the contact length between the workpiece and the rotary grindstone is L and the spindle rotation speed is ω, the spindle relative to the spindle rotation angle is changed so that ω changes in proportion to 1 / L. The rotation speed is calculated.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, the main shaft rotation speed correcting means sets the main shaft rotation speed as a correction start point or a correction end point at an angle where the amount of change in the rotation speed in the lift portion exceeds a specified range. The speed is modified.

[0014]

Therefore, according to the first aspect of the present invention, the first
Calculates the contact length of the rotating grindstone with the workpiece. Then, the main shaft rotation speed with respect to the rotation angle of the main shaft is calculated by the second calculating means based on the calculated contact length. That is, as the contact length increases, the frictional resistance generated in the processed portion increases.
Therefore, in such a case, the rotational speed of the main shaft is reduced to suppress an increase in frictional resistance. On the other hand, if the contact length is small, the frictional resistance generated in the machined part will be small,
In such a case, the rotation speed of the main shaft is increased. As a result, even if the contact length changes with the rotation of the workpiece, the thermal influence on the workpiece is made uniform, and the quality of the finished surface is improved.

In addition, the moving position of the grindstone with respect to the time change is obtained by the third calculating means from the spindle speed thus obtained, and the moving acceleration of the grindstone is calculated by the fourth calculating means. As a result, when the moving acceleration exceeds the specified value by the determining means, the reference main spindle rotation speed serving as a reference for calculating the main spindle rotation speed is corrected by the reference main spindle rotation speed correcting means, and the second, third, and second rotation speeds are corrected. When the determination means determines that the value is within the specified value through the calculation means of step 4, the spindle rotation control data determining means determines the latest reference spindle rotation speed and, based on this, the spindle rotation speed with respect to the spindle rotation angle. Determined as data. Then, at the time of grinding, the rotating means is controlled based on the determined spindle rotation control data.

As described above, by appropriately setting the rotation speed of the main spindle within a range not exceeding the capability of the moving means of the rotary grindstone so as to follow the rotation of the main spindle, smooth control of the rotating means and the moving means is performed. It will be.

According to the second aspect of the present invention, the spindle rotational speed ω
Changes in proportion to 1 / L. In other words, the main shaft rotation speed ω decreases as the contact length L increases, and increases as the contact length L decreases.

According to the third aspect of the present invention, the second calculating means converts the contact length into data corresponding to the spindle rotation angle from the calculation result by the first calculating means, and then, based on this data, Since the spindle rotation speed with respect to the spindle rotation angle is calculated, the calculation is easily performed.

According to the fourth aspect of the present invention, the second calculating means calculates the spindle rotation speed with respect to the workpiece angle based on the calculation result by the first calculation means, and then calculates this spindle rotation speed. To convert to data corresponding to the rotation angle,
Calculation is easy.

According to the fifth aspect of the present invention, the reference spindle rotational speed correcting means calculates a correction amount of the reference spindle rotational speed according to a difference between the maximum value of the moving acceleration of the rotary grindstone and a specified value,
In order to provide an appropriate correction amount, correction of the reference spindle rotation speed and calculation of the rotation speed are performed in a short time.

According to the sixth aspect of the present invention, the first calculating means calculates the contact length of the rotary grindstone with the workpiece. Then, the main shaft rotation speed with respect to the rotation angle of the main shaft is calculated by the second calculating means based on the calculated contact length. That is, as the contact length increases,
The frictional resistance generated in the processed part increases. Therefore, in such a case, the rotational speed of the main shaft is reduced to suppress an increase in frictional resistance. On the other hand, if the contact length is small, the frictional resistance generated in the machined portion becomes small, and in such a case, the rotation speed of the main shaft is increased. As a result, even if the contact length changes with the rotation of the workpiece, the thermal influence on the workpiece is made uniform, and the quality of the finished surface is improved.

Further, from the spindle rotation speed obtained in this way, the third calculation means calculates the rotation speed change amount between the main spindle rotation angle and the main spindle unit rotation angle. As a result of this calculation, the judgment means determines the rotation speed change amount. If the amount is outside the specified range, the main spindle rotation speed correcting means sets
The main shaft rotation speed is corrected so as to widen the minimum rotation speed width of the lift portion with respect to the main shaft rotation speed with respect to the main shaft rotation angle calculated by the calculation unit, and the corrected main shaft rotation speed and the main shaft rotation control data determination unit The reference spindle rotation speed is determined as spindle rotation control data. Alternatively, when it is determined by the determining means that the rotation is within the specified range, the main spindle rotation speed and the reference main spindle rotation speed with respect to the main spindle rotation angle calculated by the second calculating means are determined by the main spindle rotation control data determining means. Is determined as Then, at the time of grinding, the rotating means is controlled based on the determined spindle rotation control data.

As described above, since the spindle rotation speed is corrected so that data at a portion where the variation of the spindle rotation speed is large is particularly low, the rotation speed of the spindle is controlled by the rotation speed control data during grinding. In this case, abnormal machining is avoided even if there is some time lag in speed.

According to the seventh aspect of the present invention, the spindle rotational speed ω
Changes in proportion to 1 / L. In other words, the main shaft rotation speed ω decreases as the contact length L increases, and increases as the contact length L decreases.

According to the eighth aspect of the present invention, the main spindle rotational speed correcting means corrects the main spindle rotational speed by using an angle at which the rotational speed variation exceeds a specified range in the lift portion as a correction start point or a correction end point. The data is corrected at an appropriate angular position, so that good processing is performed even if there is a slight speed change.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment in which the present invention is embodied in a grinding machine will be described below with reference to FIGS.

As shown in the partially cutaway side view of FIG. 1 and the plan view of FIG. 2, the work support table 1 is mounted on a top surface of one side of the base 2 by a moving mechanism (not shown) in the horizontal direction (Z direction in FIG. 2). ) Is movably supported. The headstock 3 is disposed on the upper surface of the work support 1, and has a spindle 4 for detachably supporting one end of the camshaft W, and a spindle motor composed of a servomotor as a rotating means for rotating the spindle 4. 5 is provided. Also, a plurality of cam-shaped workpieces Wa are formed on the camshaft W at predetermined intervals in the axial direction, and the outer peripheral surfaces of these workpieces Wa are ground surfaces Wb. The workpiece Wa is formed as a non-circular cam 23 by grinding the ground surface Wb.

The holder 6 is disposed on the upper surface of the work support 1 such that the distance between the holder 6 and the main shaft 4 can be adjusted. The camshaft W is rotatable so as to extend in the Z direction between the main shaft 4 and the holder 6. It is detachably supported. Then, in this supported state, the camshaft W rotates in a predetermined direction as the main shaft motor 5 is driven. The encoder 7 is attached to the spindle motor 5, and a detection signal from the encoder 7 is input to an NC device 18 described later.

The grinding wheel head 8 is provided with a camshaft W on the base 2.
2 is supported so as to be movable in a horizontal direction (X direction in FIG. 2) orthogonal to the axis. Moving motor 9 composed of servo motor
Is mounted on the other side of the base 2, and the ball screw 10 is rotated by the moving motor 9 to
Is moved toward or away from the camshaft W. In the present embodiment, a moving means is constituted by the moving motor 9 and the ball screw 10. The encoder 11 is attached to the moving motor 9, and a detection signal from the encoder 11 is input to an NC device 18 described later. The rotary grindstone 12 is rotatably supported by a support shaft 13 at one end of the grindstone table 8 such that the grinding surface faces the camshaft W. The grinding wheel motor 14 is a grinding wheel head 8
The output of the grinding wheel motor 14 is connected to the pulley 1
The light is transmitted to the grindstone 12 via the belts 5 and 16 and the belt 17 and is rotated in one direction.

The first calculating means, the second calculating means, the third calculating means, the fourth calculating means, the judging means, the reference main spindle rotation speed correcting means, the main spindle rotation control data determining means and the NC constituting the control means The device 18 is for controlling the operation of the entire device. The NC device 18 temporarily stores a CPU (central processing unit) 19 for performing various arithmetic processing, a ROM (read only memory) 20 for storing a program for controlling the operation of the entire device, and various information. It has a RAM (random access memory) 21.

In the RAM 21, lift data based on the final cam shape after finishing is stored in advance for each of various workpieces Wa to be processed. As illustrated in FIG. 3 and FIG. 4A, the lift data is the length in the radial direction from the rotation center O to the outer peripheral surface of the finally obtained cam 23 (indicated by a two-dot chain line in FIG. 3). r (Ai) is set for each unit angle of the workpiece Wa. The angle Ai of the workpiece Wa is defined as a predetermined radial line in which each radial line indicates 0 degrees when the workpiece Wa is divided into unit angles by a straight line extending along the radial direction. It represents the angle made with respect to the object. Here, as shown in FIG. 3, assuming that the intermediate position of the base circular portion 23a of the cam 23 (the portion where the length r (Ai) in the radial direction is constant) is P1, the position P1 and the workpiece The radial line connecting the rotation center O of Wa is set as a radial line indicating 0 degrees (= angle A1).

That is, as shown in the flowchart of FIG. 5, the NC device 18 determines the lift data r (Ai) in step S1 according to the type of the work, and in step S2, cuts the grinding wheel 12 into the workpiece Wa. Determine the amount ΔH. The cutting amount ΔH is defined as a depth of the grinding wheel 12 cut from the outer peripheral surface of the workpiece Wa when the workpiece Wa makes one rotation, and a tangent line in contact with the outer peripheral surface of the workpiece Wa. It is represented by a length in a direction orthogonal to the direction.

Further, in step S3, the grinding stone 12
Is determined, the NC device 18 determines in step S
In 4, the main shaft rotation angle θ (Ai) when the workpiece Wa contacts the grindstone 12 at each angle Ai is calculated and stored in the RAM 21.

That is, as shown in FIG.
Spindle angle θ (A) when the grinding point Qi of the grindstone 12 with respect to
Find i). The main shaft rotation angle θ (Ai) is set such that the angle θ (A1) when the grinding point Qi corresponds to the position P1 on the workpiece Wa is 0 degree.

The grinding point Q of the grindstone 12 with respect to the workpiece Wa
If i is always located on a straight line connecting the rotation center O of the workpiece Wa and the rotation center Pi of the grindstone 12, the workpiece W
a and the corresponding spindle rotation angle θ (Ai)
Is always the same value. However, as shown in FIG.
When the workpiece Wa having a non-circular shape is ground by the grindstone 12 having a predetermined radius R, the grinding point Qi shifts up and down with respect to a straight line connecting both rotation centers O and Pi. Therefore, the angle Ai of the workpiece Wa and the corresponding spindle rotation angle θ (Ai) do not always have the same value. As a result, for the angle Ai of the workpiece Wa set for each equal angle, the main shaft rotation angle θ (Ai) is not calculated as a value for each equal angle.

Based on this relationship, the NC device 18
In step S5, the rotation angle θi of the spindle 4 and the grindstone 1
The profile data Xi is calculated as control data that sets the relationship with the movement position 2 of the wheel head 8, that is, the movement position X of the grinding wheel head 8, and is stored in the RAM 21. As shown in FIG. 4B, the profile data Xi indicates the movement position X of the grinding wheel head 8 in the X direction during one rotation of the spindle 4,
Are set for each unit rotation angle.

That is, the lift data r (Ai) corresponding to the spindle rotation angle θ (Ai) in FIG.
As shown in (b), the distance ri and the grinding wheel radius R are converted into a distance ri between the rotation center O of the workpiece Wa and the grinding point Qi corresponding to the main shaft rotation angle θi at equal angles. , The profile data Xi is calculated.

In step S6, the NC device 18 determines the contact length of the grindstone 12 with the workpiece Wa based on the lift data r (Ai), the cutting depth ΔH, the grindstone radius R, and the like (thick line in FIG. 3). L (Ai) is calculated corresponding to the angle Ai of the workpiece Wa, respectively, and
1 is stored. That is, as shown in FIG.
a when the grinding point Qi of the grindstone 12 with respect to the workpiece a corresponds to the position of each angle Ai on the workpiece Wa.
Find i). Subsequently, the NC device 18 performs step S7.
In the above, based on the relationship calculated in step S4, the contact length L (Ai) is calculated by an interpolation operation (for example, a spline interpolation operation) using a predetermined interpolation formula for each of the main shaft rotation angles θi at equal angles. To the contact length Li corresponding to
Store it in AM21.

FIG. 6 is a graph showing the relationship between the rotation angle θi of the main shaft 4 and the contact length Li.

As is clear from the figure, the contact length Li of the grindstone 12 with the workpiece Wa greatly changes with the rotation of the main shaft 4.

Next, a main shaft rotation speed ωi is calculated with respect to the main shaft rotation angle θi so as to obtain main shaft rotation control data. First, in step S8, the base circle portion 23a
Is set. The reference main spindle rotation speed ω0 is a main spindle rotation speed when the base circle portion 23a of the cam 23 is in contact with the grindstone 12, and the preset reference main spindle rotation speed ω0 is used at first.
Then, in step S9, as shown in FIG. 4 (b), the NC device 18 adjusts the spindle speed so that the rotation speed ωi of the spindle 4 changes according to the calculated value of the contact length Li. ωi is calculated for each unit rotation angle of the main shaft 4 and stored in the RAM 21.

More specifically, the NC device 18 calculates the rotation speed ωi of the main shaft 4 using the following equation (1).

Ωi = K1 × ω0 × (L0 / Li) (1) Here, L0 is the contact length of the grindstone 12 at the base circle portion 23a of the cam 23. K1 is a correction coefficient specific to the device, and is set in advance for each device.

As shown in FIG. 6 and FIG.
As described above, the contact length L
i changes. Accordingly, when the main shaft rotation speed ω0 when the base circle portion 23a of the cam 23 is in contact with the grindstone 12 is set as a reference rotation speed, the rotation speed ωi of the main shaft 4 is in contact with the reference rotation speed ω0. The spindle rotation speed ωi is calculated for each unit rotation angle of the spindle 4 according to the above equation (1) so as to change in inverse proportion to the length Li. In other words, the main shaft rotation speed ωi is set to change in proportion to 1 / Li. As a result, the main shaft rotation speed ωi is set smaller as the contact length Li increases, and set larger as the contact length Li decreases.

FIG. 7 shows that the reference spindle rotational speed ω0 is, for example, 5
6 is a graph showing a relationship between a main shaft rotation angle θi and a main shaft rotation speed ωi based on data calculated from the above equation (1) when set to 0 rpm.

When the spindle rotation speed ωi shown in this graph is used as spindle rotation control data during grinding, the rotation of the spindle 4 is controlled based on the control data.
Following the rotation of the main shaft 4, the movement of the grinding wheel head 8 is controlled based on the profile data Xi. Usually, a specified value αa indicating the maximum of the movement acceleration α is preset in the movement motor 9 in accordance with the performance thereof. This specified value α
It is necessary to consider the movement acceleration α of the grinding wheel head 8 with respect to the calculated control data in order to operate the motor so as not to exceed a.

For this reason, the NC device calculates the wheel head movement acceleration α with respect to the change in the time t in steps S10 to S12. In step S10, based on the spindle rotation speed ωi with respect to the spindle rotation angle θi calculated in step S9 and the profile data Xi calculated in step S5, the wheel head position X with respect to the change in time t is calculated. FIG. 8 is a graph showing the relationship between the time t and the wheel head position X based on the calculated data. Next, in step S11, a wheel head moving speed v is calculated from the data of the wheel head position X. FIG.
Is a graph showing the relationship between the time t and the wheel head moving speed v based on the calculated data. Further, in step S12, a wheel head moving acceleration α is calculated from the data of the wheel head moving speed v. FIG. 10 is a graph showing changes in the time t and the grinding wheel moving acceleration α based on the calculated data.

Then, in step S13, the wheel head moving acceleration α is compared with a specified value αa. As shown in FIG. 10, a particularly high acceleration α portion is seen corresponding to the two lift portions 23c and 23d in the projecting portion 23b of the cam 23. It is determined whether or not the maximum value αh at this point is within the specified value αa. In FIG. 10, it clearly exceeds the specified value αa. In such a case, in step S14, the value set in step S8 is set. The reference spindle speed ω0 is corrected so that its value is reduced. The correction amount △ ω0 is performed by a predetermined amount. Alternatively, it is also possible to obtain the correction amount △ ω0 according to the difference between the maximum value αh and the specified value αa by calculation. With this correction, steps S8 to S13 are repeated again.

In step S8, the reference spindle rotational speed ω0 corrected in step S14 is set, and in step S9, the spindle rotational speed ωi is similarly calculated. FIG. 11 is a graph showing the relationship between the main shaft rotation angle θi and the main shaft rotation speed ωi when the reference main shaft rotation speed ω0 is corrected to, for example, 37 rpm in FIG.

Further, steps S10 to S
12, the calculation of the grinding wheel movement acceleration α is performed in the same manner. As a result, FIG. 12 is a graph showing the relationship between the time t and the wheel head movement acceleration α.

Then, in step S13, the maximum value αh of the wheel head movement acceleration α is reduced to within the specified value αa, and is compared with the specified value αa. It is determined that there is. With this determination, the control data of the spindle rotation is determined in step S15. That is, the latest main spindle rotation speed ω0 and the main spindle rotation speed ωi with respect to the main spindle rotation angle θi set and calculated in the immediately preceding steps S8 and S9 are determined as main spindle rotation control data.
Is stored.

That is, step S6 corresponds to first calculating means, steps S7, S8, and S9 correspond to second calculating means, step S10 corresponds to third calculating means, and steps S11 and S12. Corresponds to the fourth calculating means, step S13 corresponds to the determining means, and step S1
Reference numeral 4 corresponds to reference spindle rotation speed correction means, and step S15 corresponds to spindle rotation control data determination means.

The spindle rotation control data ω thus set
Grinding of the workpiece Wa is performed based on 0, ωi and the profile data Xi.

At the time of grinding, the NC device 18 calculates the rotation speed ω with respect to the rotation angle θ of the main shaft 4 based on the detection signals from the encoders 7 and 11, and moves the wheel head 8 in the X direction. And so on. And
The NC device 18 as a control means controls the rotation of the spindle motor 5 and the movement motor 9 based on the result of these calculations and the set spindle rotation speed ωi and the profile data Xi, and moves the spindle 4 to its rotation angle θi. At the same time, the grindstone head 8 is moved in the X direction in accordance with the rotation angle θi of the main shaft 4. Also, the NC device 1
8 controls the movement of the work support base 1 in the Z direction, and arranges a predetermined workpiece Wa so as to face the grindstone 12.
As a result, the predetermined work Wa is lift data r
(Ai) was ground into a non-circular shape corresponding to FIG.
A cam 23 is formed as shown by the chain line.

In the cam grinding machine configured as described above, the contact length Li of the grindstone 12 with respect to the workpiece Wa is determined based on the cutting amount ΔH of the grindstone 12 with respect to the workpiece Wa. It is calculated for each unit rotation angle. Then, the main shaft rotation speed ωi is changed so that the rotation speed ωi of the main shaft 4 changes according to the value of the calculated contact length Li.
i is set for each unit rotation angle of the main shaft 4. Then, during grinding, the rotation of the spindle motor 5 is controlled for each unit angle of the spindle 4 based on the set spindle rotation speed ωi.

That is, since the cam 23 has a non-circular shape, the contact length Li, in other words, the frictional resistance generated in the processed portion changes with the rotation of the workpiece Wa. When the contact length Li (frictional resistance) increases, the thermal effect on the workpiece Wa increases. However, in such a case, the rotation of the spindle motor 5 is controlled so that the rotation speed ωi of the spindle 4 becomes slow, and the machining load is controlled. On the other hand, when the contact length Li (frictional resistance) decreases, the rotation of the spindle motor 5 is controlled so that the rotation speed ωi of the spindle 4 increases.

As a result, this embodiment has the following effects.

(1) Even if the contact length Li changes with the rotation of the workpiece Wa, the frictional resistance generated in the processed portion is made uniform, and thermal damage such as grinding burns and grinding cracks is caused. And a high-quality finished surface can be obtained.

(2) As the contact length Li changes, the rotational resistance to the grindstone 12 also changes in proportion. But,
Also in this case, as described above, the spindle motor 5 is driven so that the rotation speed ωi of the spindle 4 changes according to the change in the contact length Li.
Is controlled, the fluctuation of the load on the grinding wheel motor 14 for rotating the grinding wheel 12 is suppressed.
2 rotates smoothly without generating micro-vibration, enabling high-precision machining.

(3) In this embodiment, the contact length Li
Is calculated for each unit rotation angle of the main shaft 4, and based on them, the rotation speed ωi of the main shaft 4 is set in advance for each unit rotation angle of the main shaft 4. Then, at the time of grinding, the rotation of the spindle motor 5 is controlled for each unit rotation angle of the spindle 4 based on the set spindle rotation speed ωi. By setting the rotation speed ωi of the spindle 4 in advance before grinding, the spindle motor 5 can be controlled smoothly. Further, the spindle motor 5 can be accurately and reliably controlled for each unit rotation angle of the spindle 4.

(4) Further, with respect to the spindle rotational speed ωi calculated as described above, a movement acceleration α of the grinding wheel head 8 following the main shaft rotation speed ωi is calculated, and the acceleration α is set within the specified value αa. By correcting the reference spindle rotation speed ω0, the spindle rotation speed ωi with respect to the spindle rotation angle θi is corrected based on the reference spindle rotation speed ω0, so that a smooth operation can be performed without exerting an excessive force on the motor for moving the grinding wheel head 8. As a result, improvement in processing accuracy can be realized.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS.

In the second embodiment, as shown in the flowchart of FIG. 14, steps S1 to S6 and steps S10 to S15 are performed in the same procedure as in the first embodiment. The procedure for calculating the spindle rotation speed ωi with respect to the spindle rotation angle θi between S10 and S10 is different from that of the first embodiment.

That is, by step S6, FIG.
As shown in (a), after the lift data r (Ai) and the contact length L (Ai) are set in the RAM 21 corresponding to the angle Ai of the workpiece Wa, the NC device 18 returns to the basic state in step S8. Reference spindle rotation speed ω0 of the circular portion 23a
Is set, then, in step S16, based on the reference main shaft rotation speed ω0, the main shaft rotation speed ω (Ai) that changes according to the value of the contact length L (Ai) is calculated by the following equation (2). ).

Ω (Ai) = K1 × ω0 × (L0 / L (Ai)) (2) The spindle rotational speed ω (A) calculated according to the above equation (2)
i) corresponds to the angle of the workpiece, that is, the main shaft rotation angle θ (Ai) that is not equal to each other. Therefore, next, in step S9, the spindle rotation speed ω (Ai) corresponding to the spindle rotation angle θ (Ai).
Is converted into a spindle rotation speed ωi corresponding to the spindle rotation angle θi for each equal angle as shown in FIG. That is, based on the main spindle rotation angle θ (Ai) and the corresponding main spindle rotation speed ω (Ai), the main spindle rotation angle θi for each equal angle is obtained by an interpolation operation (for example, a spline interpolation operation) using a predetermined interpolation formula. Is calculated.

In this embodiment, step S6 corresponds to first calculating means, steps S8, S16, and S9 correspond to second calculating means, step S10 corresponds to third calculating means, and step S10 corresponds to third calculating means. Steps S11 and S12 correspond to a fourth calculating unit, step S13 corresponds to a determining unit, step S14 corresponds to a reference main shaft rotation speed correcting unit, and step S15 corresponds to a main shaft rotation control data determining unit.

Also in this case, similarly to the above embodiment, the NC device 18 as the control means controls the spindle motor 5 so that the rotational speed ωi of the spindle 4 changes according to the contact length Li. Control can be performed for each unit rotation angle of the main shaft 4. Other functions and effects are the same as those of the first embodiment.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS.

In the third embodiment, as shown in the flowchart of FIG. 15, steps S1 to S9 are the same as those of the first embodiment described above, and a description thereof will be omitted. In the third embodiment, the method of determining the spindle rotation control data after the spindle rotation speed ωi that changes according to the contact length Li is calculated in step S9 is different from that of the first embodiment.

That is, in step S9, the spindle rotation angle θ
After the main shaft rotation speed ωi for i is calculated, in step S17, the rotation speed change amount dω / dθ between the main shaft unit rotation angles θi with respect to the main shaft rotation angle θi is calculated based on the calculated main shaft rotation speed ωi. FIG. 16 is a graph showing the relationship between the spindle rotation angle θi and the spindle rotation speed ωi based on the calculation result of step S9, and FIG. 17 is calculated in step S17 based on the calculation data of the spindle rotation speed ωi. 6 is a graph showing a relationship between a main spindle rotation angle θi and a main spindle rotation speed variation dω / dθ between main spindle unit rotation angles.

After the main shaft rotation speed change dω / dθ is calculated, it is determined in step S18 whether the speed change dω / dθ is within a specified range. As shown in FIG. 17, both lift portions 23c, 23 of the cam 23
Especially near the start point and the end point of d, the speed change dω /
There are angular positions θa and θb where dθ changes greatly.

When the data of the spindle rotation speed ωi having such a speed change dω / dθ is used as the spindle rotation control data and the grinding is performed, for example, even if a slight time lag occurs in the rotation of the spindle 4. In other words, when an angle shift occurs, the grinding is performed at a rotational speed completely opposite to the rotational speed ωi adapted to the grinding point Qi of the workpiece Wa, so that abnormal machining may occur at that position. There is. In order to prevent such a situation, step S1
8, S19 are provided.

In step S18, it is determined whether or not the rotational speed variation dω / dθ exceeds the specified range E. In FIG. 17, there is clearly one exceeding the specified range E. In such a case, in step S19, the data of the main shaft rotation speed ωi calculated in step S9 is mainly corrected for the lift portions 23c and 23d. Do. This correction increases the widths of the minimum rotation speeds ωL1 and ωL2 in the angle θ direction as shown by the two-dot chain line in FIG. 16 in accordance with the minimum rotation speeds ωL1 and ωL2 of the calculated values shown by the solid lines in FIG. Correct the data to In this method, the angle may be simply corrected to a predetermined width. However, in this case, the angular positions θa and θb where the speed change amount dω / dθ exceeds the specified range E are determined as the correction start or end points. Modify so that the line of the final rotation speed is extended. By making such a correction, the data at the portion where the variation dω / dθ of the spindle rotational speed ωi based on the theoretical calculation is large is set low, so that good machining can be performed.

In step S20, the main shaft rotation speed ωi and the reference main shaft rotation speed ω0 with respect to the corrected main shaft rotation angle θi are determined as main shaft rotation control data, or as a result of the determination in step S18, the rotation speed change amount is determined. When dω / dθ is within the specified range E, the main shaft rotation speed ωi and the reference main shaft rotation speed ωi with respect to the main shaft rotation angle θi calculated in step S9 are determined as main shaft rotation control data and stored in the RAM 21.

That is, step S6 corresponds to the first calculating means, steps S7, S8 and S9 correspond to the third calculating means, step S17 corresponds to the rotational speed change amount calculating means, and step S18 corresponds to the rotational speed change amount calculating means. Step S19 corresponds to the spindle rotation speed correcting means, and step S20 corresponds to the spindle rotation control data determining means.

At the time of grinding, the NC device 18 as a control means controls the spindle motor 5 and the motor 9 for moving the grindstone head 8 based on the set spindle rotation control data ω0, ωi and the profile data Xi. Is controlled.

As described above, the rotation speed ωi of the main shaft 4 changes in accordance with the contact length Li between the workpiece Wa and the grindstone 12, and the rotation speed change dω / unit rotation angle between the unit rotation angles accordingly. The main shaft rotation speed ωi is set so that the data in the portion where dθ is large is low.

As a result, this embodiment has the following effects.

(1) Even if the contact length Li changes with the rotation of the workpiece Wa, the frictional resistance generated in the machined portion is made uniform and thermal damage such as grinding burns and grinding cracks is caused. And a high-quality finished surface can be obtained.

(2) With the change of the contact length Li, the rotational resistance to the grindstone 12 also changes in proportion. But,
Also in this case, as described above, the spindle motor 5 is driven so that the rotation speed ωi of the spindle 4 changes according to the change in the contact length Li.
Is controlled, the fluctuation of the load on the grinding wheel motor 14 for rotating the grinding wheel 12 is suppressed.
2 rotates smoothly without generating micro-vibration, enabling high-precision machining.

(3) In this embodiment, the contact length Li
Is calculated for each unit rotation angle of the main shaft 4, and based on them, the rotation speed ωi of the main shaft 4 is set in advance for each unit rotation angle of the main shaft 4. Then, at the time of grinding, the rotation of the spindle motor 5 is controlled for each unit rotation angle of the spindle 4 based on the set spindle rotation speed ωi. By setting the rotation speed ωi of the spindle 4 in advance before grinding, the spindle motor 5 can be controlled smoothly. Further, the spindle motor 5 can be accurately and reliably controlled for each unit rotation angle of the spindle 4.

(4) When the spindle rotation is controlled based on the rotation control data ω0 and ωi set in this embodiment, abnormal machining can be avoided even if there is a slight time lag in speed. .

(5) In the lift portions 23c and 23d, the main shaft rotational speed ωi is corrected by setting the angular position where the rotational speed variation dω / dθ exceeds the specified range E as a correction start point or a correction end point. Data correction can be performed at an appropriate angle position, and thereby good machining can be performed even if there is a minute speed change.

[0084]

As described in detail above, according to the present invention,
It has the following excellent effects.

According to the first aspect of the present invention, the rotating means is controlled so that the rotational speed of the main shaft changes in accordance with the contact length of the rotary grindstone with the workpiece, so that the frictional resistance during the grinding process is reduced. This is an excellent effect that the increase in the quality can be suppressed and the deterioration of the processing quality can be prevented. In addition, the rotation means can be smoothly controlled, and accurate and reliable control can be performed for each unit rotation angle of the main shaft.

Further, by properly setting the rotation speed of the main spindle within a range not exceeding the capability of the moving means of the rotary grindstone so as to follow the rotation of the main spindle, the rotating means and the moving means can be controlled smoothly.

According to the second aspect of the present invention, the spindle rotational speed ω
Can be reduced as the contact length L increases, and can be increased as the contact length L decreases.

According to the third aspect of the present invention, after the contact length is converted into data corresponding to the spindle rotation angle, the spindle rotation speed with respect to the spindle rotation angle is calculated based on this data. It can be carried out.

According to the fourth aspect of the present invention, after calculating the spindle rotation speed with respect to the workpiece angle, the spindle rotation speed is converted into data corresponding to the spindle rotation angle, so that the calculation can be easily performed. .

According to the fifth aspect of the present invention, the correction amount of the reference spindle rotational speed is calculated according to the difference between the maximum value of the moving acceleration of the rotary grindstone and the specified value, and an appropriate correction amount is given. Correction of the reference spindle rotation speed and calculation of the rotation speed can be performed in a short time.

According to the sixth aspect of the present invention, the rotating means can be controlled so that the rotation speed of the main shaft changes in accordance with the length of contact of the rotary grindstone with the workpiece, so that the frictional resistance during grinding can be increased. An excellent effect of suppressing the deterioration of the processing quality can be achieved. In addition, the rotation means can be smoothly controlled, and accurate and reliable control can be performed for each unit rotation angle of the main shaft.

In addition, the main shaft rotation speed is corrected so as to widen the angle width at which the minimum rotation speed is given, especially for a lift portion at an angle where the rotation speed changes rapidly.
When the rotation speed of the main shaft is controlled by the rotation speed control data, even if there is a slight time lag of the speed, occurrence of abnormal machining can be prevented.

According to the seventh aspect of the present invention, the spindle rotational speed ω
Can be reduced as the contact length L increases, and can be increased as the contact length L decreases.

According to the eighth aspect of the present invention, the main spindle rotational speed correcting means corrects the main spindle rotational speed by using an angle at which the rotational speed variation exceeds a specified range in the lift portion as a correction start point or a correction end point. The data can be corrected at an appropriate angle position, so that good processing can be performed even if there is a minute speed change.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of a grinding machine embodying the present invention, showing one embodiment of a non-circular body grinding apparatus according to the present invention.

FIG. 2 is a plan view of the grinding machine shown in FIG.

FIG. 3 is a schematic diagram for explaining a grinding state of a workpiece Wa.

4A and 4B show a first embodiment, and FIG. 4A shows lift data r (Ai), contact length L (Ai), and spindle rotation angle θ (Ai) corresponding to an angle Ai of a workpiece Wa. FIG. 7B is an explanatory diagram showing the distance ri, the profile data Xi, the contact length Li, and the spindle rotation speed θi with respect to the spindle rotation angle θi for each equal angle.

FIG. 5 is a first diagram showing a procedure up to determination of spindle rotation control data.
It is a flowchart of an embodiment.

FIG. 6 is a graph showing a relationship between a spindle rotation angle θi and a contact length Li.

FIG. 7 is a graph showing a relationship between a spindle rotation angle θi and a spindle rotation speed ωi corresponding to a contact length Li.

FIG. 8 is a graph showing a relationship between a time t and a wheel head position X;

FIG. 9 is a graph showing the relationship between time t and wheelhead moving speed v.

FIG. 10 is a graph showing the relationship between time t and wheelhead movement acceleration α.

FIG. 11 shows the corrected spindle rotation angle θi and spindle rotation speed ω
It is a graph which shows the relationship with i.

FIG. 12 is a graph showing a relationship between a time t based on a corrected spindle rotation speed ωi and a wheel head movement acceleration α.

FIG. 13 shows a second embodiment, in which (a) shows a workpiece Wa.
Is an explanatory diagram showing lift data r (Ai), contact length L (Ai), spindle rotation speed ω (Ai), and spindle rotation angle θ (Ai) corresponding to the angle Ai of FIG. FIG. 9 is an explanatory diagram showing a distance ri, profile data Xi, and main shaft rotation speed ωi corresponding to a rotation angle θi.

FIG. 14 is a flowchart of a second embodiment showing a procedure up to determination of spindle rotation control data.

FIG. 15 is a flowchart of a third embodiment showing a procedure up to determination of spindle rotation control data.

FIG. 16 is a graph illustrating a relationship between a spindle rotation angle θi and a spindle rotation speed ωi corresponding to a contact length Li for explaining the third embodiment.

FIG. 17 is a diagram illustrating a spindle rotation speed change dω / d between a spindle rotation angle θi and a spindle unit rotation angle for explaining the third embodiment;
It is a graph which shows the relationship with d (theta).

FIG. 18 is a schematic diagram for explaining a grinding state of a workpiece Wa.

[Explanation of symbols]

Reference Signs List 4 spindle 5 spindle motor (rotating means) 8 wheel head 9 moving motor (moving means) 10 ball screw (moving means) 12 rotating wheel 14 grinding wheel motor 18 first calculating means, second calculating means, third NC including a calculating means, a fourth calculating means, a determining means, a rotational speed correcting means, a spindle rotation control data determining means and a controlling means, etc.
Apparatus 23 Cam Wa Workpiece O Rotation center θi Spindle rotation angle ΔH Cutting amount Li Contact length Qi Grinding point ri Distance between rotation center and grinding point ω0 Reference spindle rotation speed ωi Spindle rotation speed x Wheelhead moving position α Wheel head movement acceleration αa Specified value △ ω0 Correction amount dω / dθ Spindle rotation speed change E Specified range

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yu Owada Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama, Japan (72) Inventor Tatsuomi Nakayama 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa (72) Inventor Toshiichi Otani 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Minoru Ota 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. In-company (72) Inventor Katsutoshi Miyahara 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56) References JP-A-9-97103 (JP, A) JP-A-62-34765 (JP) , A) JP-A-4-331059 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G05B 19/18-19/46 B23Q 15/00-15/28 B24B 1/00 -1/04 B24B 9/00-19/28 B2 4B 41/00-51/00

Claims (8)

(57) [Claims] 1. A spindle comprising: a rotating means for rotating a spindle on which a workpiece is mounted; and a moving means for relatively moving a rotary grindstone for grinding an outer peripheral surface of the workpiece in a direction intersecting the spindle. A non-circular body that grinds a workpiece into a predetermined non-circular shape by controlling the moving means based on control data that sets the relationship between the rotation angle of the main shaft and the moving position of the rotating grindstone while rotating A first calculating means for calculating a contact length between the workpiece and the rotary grindstone with respect to the workpiece angle based on a cutting amount of the rotary grindstone with respect to the workpiece, and a non-circular base circle Second calculating means for calculating a spindle rotation speed with respect to the spindle rotation angle based on the reference spindle rotation speed set in advance corresponding to the portion and the calculated contact length; and Based on control data A third calculating means for calculating a moving position of the rotating grindstone with respect to time change, a fourth calculating means for calculating a moving acceleration of the rotating grindstone with respect to time change based on the calculated moving position, Determining means for determining whether or not the moving acceleration is within a predetermined value, and correcting the reference rotation speed based on the result of the determination when the moving acceleration exceeds a predetermined value. And a reference spindle rotational speed correcting means for causing the second to fourth calculating means to perform the calculation again. Based on the result of the determination, when the moving acceleration is within a specified value, the latest reference spindle rotational speed Spindle rotation control data determining means for determining spindle rotation speed data for the latest spindle rotation angle based on this as spindle rotation control data; Control means for controlling the rotation means based on the rotation control data, so that the rotation speed of the spindle changes according to the contact length between the workpiece and the rotation grindstone, and the movement of the rotation grindstone accompanying this An apparatus for grinding a non-circular body, wherein a rotation speed of a spindle is set so that acceleration is within a specified value. 2. The method according to claim 1, wherein when the contact length between the workpiece and the rotary grindstone is L and the spindle rotational speed is ω, ω changes in proportion to 1 / L. 2. The non-circular body grinding device according to claim 1, wherein the spindle rotation speed is calculated. 3. The non-circular body grinding apparatus according to claim 1, wherein said second calculating means has means for calculating a contact length with respect to a spindle rotation angle from a calculation result by said first calculating means. 4. The non-round body grinding apparatus according to claim 1, wherein said second calculating means has means for calculating a main shaft rotation speed with respect to a workpiece angle from a calculation result by said first calculating means. . 5. The reference spindle rotation speed correcting means includes means for calculating a correction amount of the reference spindle rotation speed in accordance with a difference between the maximum value of the moving acceleration of the rotary grindstone and the specified value. The non-circular body grinding device according to any one of the above. 6. A spindle comprising: a rotating means for rotating a spindle on which a workpiece is mounted; and a moving means for relatively moving a rotary grindstone for grinding an outer peripheral surface of the workpiece in a direction intersecting the spindle. A non-circular body that grinds a workpiece into a predetermined non-circular shape by controlling the moving means based on control data that sets the relationship between the rotation angle of the main shaft and the moving position of the rotating grindstone while rotating A first calculating means for calculating a contact length between the workpiece and the rotary grindstone with respect to the workpiece angle based on a cutting amount of the rotary grindstone with respect to the workpiece, and a non-circular base circle Second calculating means for calculating a main shaft rotation speed with respect to the main shaft rotation angle based on the reference main shaft rotation speed set in advance corresponding to the portion and the calculated contact length, based on the calculated main shaft rotation speed Spindle rotation angle A rotation speed change amount calculating means for calculating a rotation speed change amount between the main spindle unit rotation angles with respect to, a determining means for determining whether or not the calculated rotation speed change amount is within a preset specified range, As a result, when the rotational speed variation exceeds a specified range, the spindle rotational speed is increased so that the minimum rotational speed width in the non-circular lift portion is increased with respect to the spindle rotational speed by the second calculating means. Spindle rotation speed correction means for correcting, the main shaft rotation speed and the reference main shaft rotation speed for the corrected main shaft rotation angle are determined as main shaft rotation control data, or the rotation speed change amount is determined based on the result of the determination. When within the specified range, the spindle rotation speed for determining the spindle rotation speed with respect to the spindle rotation angle by the second calculation means and the reference spindle rotation speed as spindle rotation control data. Control data determination means, and control means for controlling the rotation means based on the determined spindle rotation control data at the time of grinding, wherein the rotation speed of the spindle depends on the contact length between the workpiece and the rotary grindstone. A non-circular body grinding apparatus characterized in that the main shaft rotation speed is set so as to change the rotation speed and to reduce the data in a portion where the rotation speed change amount between the unit rotation angles is large. 7. The second calculating means is arranged such that when the contact length between the workpiece and the rotary grindstone is L and the spindle rotation speed is ω, ω changes in proportion to 1 / L. 7. The non-circular body grinding device according to claim 6, wherein a spindle rotation speed with respect to the spindle rotation angle is calculated. 8. The method according to claim 6, wherein said main spindle rotational speed correcting means corrects the main spindle rotational speed with a correction start point or a correction end point at an angle at which the rotational speed change amount exceeds a specified range in the lift portion. A perfect circular grinding machine.