KR102229779B1 - The Method of 4-Axis Machining for Ball Gear Cam - Google Patents

Abstract

The present invention relates to a 4-axis machining method of a ball gear cam. By processing to maintain a certain angle in a rotational direction of a rotary table one step further from the 4-axis machining at a fixed geometrical position with the turret, machining is prevented from occurring at the tip of a ball end mill tool. In other words, machining at the end of the ball end mill is not a normal cut, but crushing, which adversely affects the machining surface and tool life. Therefore, the machining method of the present invention avoiding this can increase the machining precision of the ball gear cam, and can use a ball end mill tool with a special shape without an end.

Description

The Method of 4-Axis Machining for Ball Gear Cam}

The present invention relates to a method of processing a ball gear cam, and in particular, in a 4-axis machining at a geometrical position with a turret, the end of a ball end mill tool is processed to maintain a certain angle in the rotational direction of a rotary table. It relates to a ball gear cam 4-axis machining method that prevents machining from occurring.

Gears or belts are used to transmit continuous rotational motion, but when it is necessary to transmit motion while adjusting the angle and angular speed according to an arbitrary rotational angle, a roller gear cam equipped with a rotating turret is used. It is commonly used.

In a conventional rotary turret and a roller gear cam equipped with a cam, several rollers are installed in the circumferential direction of the turret, and two rollers of the turret are in contact with the inclined surface of the cam where the groove is formed. The roller gear cam rotates according to the direction. As such a roller gear cam has little backlash and has excellent durability due to rolling contact, it requires precise driving such as an index table and an automatic tool changer (ATC). It is mainly used in place.

1 is a front view of a conventional roller gear cam.

As shown, the roller gear cam 100 is formed between the turret 10 in which a plurality of rollers 12 are installed along the side circumference and the groove 22 into which the rollers 12 are inserted, and the groove 22 It consists of a roller gear cam 20 is provided with a mountain (24).

Therefore, when the roller gear cam 20 is rotated, the roller 12 of the turret 10 maintains a stationary state or moves according to the shape of the groove 22 of the roller gear cam 20 so that the turret 10 stops or As it rotates, even if the roller gear cam 20 rotates, the position of the roller 12 is maintained as it is, so the turret remains in a stationary state, and the groove 22 of the roller gear cam 20 becomes the roller gear cam 20 ), the roller 12 is moved along the groove 22 and the turret 10 is rotated when it is formed in a form that is not parallel to the circumferential direction of the roller gear cam using a 5-axis CNC machining machine. The method is known.

However, the conventional roller gear cam is capable of processing that only controls the 5-axis at the same time, requires an expensive processing machine, and has a large processing groove, so there is a problem in that productivity is lowered.

The prior art documents below are registered patent publications filed and registered by the present applicant.

Registered Patent Publication No. 10-1744486 (2017.06.08. Announcement)

The present invention is to solve the above problems, and it is possible to process even with a 4-axis processing machine and has excellent productivity due to a small amount of processing, and durability is improved and the diameter of a turret is small because a ball that is a rigid body is used instead of a roller. It is intended to provide a 4-axis machining method for ball gear cams that can be constructed in a compact manner.

In the present invention ball gear cam 4-axis processing method, the rotation angle of the ball turret corresponding to the rotation angle of the ball gear cam is a cam diagram definition step (step 1) having a relational expression shown below,

[Relationship]

Ball gear cam rotation angles corresponding to 0°, 2°, 47°, 105°, 251°, 313°, 358°, and 360° are available at 0°, 0°, 68°, 68°, 248 Cam diagrams with °, 248°, 180°, 180°

The fitting step of transforming the cam diagram of the ball gear cam into a smooth curve by defining it in Equation 1 (step 2),

[Equation 1]

는 볼기어캠의 회전각,

Is the rotation angle of the ball gear cam,

는 터렛의 회전각

Is the rotation angle of the turret

The position of the angle where the cam curve meets the outer circumference of the ball gear cam is the rotation angle definition step defined by Equation 2 (step 3),

[Equation 2]

는 터렛의 회전각,

Is the rotation angle of the turret,

는 터렛(turret)의 중심에서 볼(ball) 중심까지의 거리,

Is the distance from the center of the turret to the center of the ball,

는 볼의 반경,

Is the radius of the ball,

R is the outermost radius of the cam,

는 캠 중심과 터렛 중심간의 거리

Is the distance between the center of the cam and the center of the turret

If the number of balls assembled so as to be rotatable on the circumference of the turret is N, the angle of the curve distance from the center of the turret to the center of the ball is defined as 360°/N. ),

The cam curve of the i-th curve is the step of obtaining the turret rotation angle of the curve defined by Equation 3 (step 5),

[Equation 3]

는 i번째 곡선의 터렛 회전각,

Is the turret rotation angle of the ith curve,

와

은 i번째 곡선의 볼기어캠의 회전각 범위

Wow

Is the rotation angle range of the ball gear cam of the i-th curve

The position coordinate value of the ball center is the step of defining the position coordinate value defined by Equation 4 (step 6)

[Equation 4]

는 위치 좌표값

Is the position coordinate value

Applying a double curve to the end of the cam curve defined by Equation 5 and Equation 6 to avoid collision when the ball enters and exits the curved part (step 7),

[Equation 5]

j=1 to j=n is defined as the connection of n points by subdividing Equation 4 into fine sections,

j1 and j2 are the positions of a certain section

는, 터렛 중심에서 볼 중심까지 추가로 멀어진 값

Is the additional distance from the center of the turret to the center of the ball

는 시작점에서의 거리

Is the distance from the starting point

는 2중 곡선이 적용되는 구간의 거리

Is the distance of the section to which the double curve is applied

는 미소요소 j에서의 곡선의 거리

Is the distance of the curve at microelement j

[Equation 6]

The rotation angle at which the direction of the tool axis always maintains a constant angle with respect to the C-axis rotation at the machining position of the work piece 14 is defined by Equation 7, and the X, Y, and Z values are changed by the additional rotation of the C-axis. It characterized in that it consists of a step (step 8) of machining by rotating the work piece defined by the value of equation 8 by a certain angle.

[Equation 7]

ε is the angle of rotation

[Equation 8]

The ball gear cam 4-axis machining method of the present invention is characterized in that a position data setting step (step 9) defined by Equation 9 is further added to the position data of the tool.

[Equation 9]

The present invention has the effect of preventing processing from occurring at the end of the ball end mill tool by processing to maintain a certain angle in the rotational direction of the rotary table by going one step from the 4-axis machining at a geometrical position with the turret.

That is, the processing at the end of the ball end mill is not a normal cutting, but a crushing phenomenon occurs, which adversely affects the processing surface or tool life, so the processing method of the present invention avoiding this can increase the processing precision of the ball gear cam. , It has the effect of using a special shape ball end mill tool that does not have an end.

1 is a front view of a conventional roller gear cam.
Figure 2 is a relationship between the roller gear cam and the turret.
3 is a diagram showing the relationship between the ball gear cam and the turret
4 is a comparison diagram of a roller gear cam groove and a ball gear cam groove.
5 is a 5-axis machining view of the roller gear cam.
6 is a 4-axis machining view of the ball gear cam.
7 is a relationship diagram (cam diagram) and an assembly relationship diagram between the ball gear cam and the turret rotation angle.
Fig. 8 is a cam curve diagram after fitting the cam diagram with a smooth MS curve.
9 is a relationship diagram representing the moment when the ball leaves the circumference of the cam.
10 is a ball gear cam circumference and cam curve diagram.
11 is a completed ball gear cam curve.
12 is a state diagram of a four-axis machine having a C-axis.
13 is a geometrical assembly relationship between the ball gear cam and the turret.
14 is a principle diagram of applying a double curve at the end of the cam curve.
15 is a principle diagram of processing so that the tangential direction of the C-axis and the direction of the tool axis are at a certain angle.

A preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. For reference, the size of the components, the thickness of the line, and the like shown in the drawings referred to in describing the present invention may be somewhat exaggerated for convenience of understanding.

In addition, terms used in the description of the present invention are defined in consideration of functions in the present invention, and thus may vary according to user, operator intention, custom, and the like. Therefore, it is appropriate to make the definition of this term based on the overall contents of the present specification.

And in the present application, terms such as'include' and'have' refer to the existence of specific numbers, steps, actions, components, parts, or a combination thereof described in the specification. It is to be understood that the presence or addition of features, numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of being excluded.

In addition, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only the present embodiment makes the disclosure of the present invention complete, and the scope of the invention is given to those of ordinary skill in the art. It is provided to be fully informed.

Therefore, in the present invention, various changes can be made and various forms can be obtained, and implementation examples (aspects) (or embodiments) will be described in detail in the specification. However, this is not intended to limit the present invention to a specific form of disclosure, and should be understood to include all changes, equivalents, or substitutes included in the technical idea of the present invention, and the expression of the singular number used in the present specification is clearly different from the context. Includes plural expressions unless they are meant to be.

However, in describing the present invention, detailed descriptions of known or known functions or configurations will be omitted in order to clarify the gist of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a diagram showing a relationship between a roller gear cam and a turret, FIG. 3 is a diagram showing a relationship between a ball gear cam and a turret, and FIG. 4 is a comparison diagram of a roller gear cam groove and a ball gear cam groove.

As shown in FIG. 2, when the roller gear cam 1 rotates, the roller 3 contacts the groove of the cam and performs rolling motion, so the turret 2 rotates according to the cam curve, as shown in FIG. As described above, when the ball gear cam 4 rotates, the ball 5 contacts the groove of the cam and makes a rolling motion, so that the turret 2 rotates according to the cam curve.

5 is a 5-axis machining view of a roller gear cam, and FIG. 6 is a 4-axis machining view of a ball gear cam.

As shown, when comparing the two cams in terms of manufacturing characteristics of the roller gear cam and the ball gear cam, the roller gear cam (1) is only possible with 5-axis simultaneous control processing using an end mill tool (8), etc. There is a disadvantage in that productivity is degraded because an expensive processing machine is required and the processing amount is large due to the large processing groove.

However, the ball gear cam 4 can be processed with a 4-axis processing machine using a ball end mill tool 9 or the like, and has an excellent productivity due to a small amount of processing.

And in terms of durability, the roller is composed of a needle bearing with a small needle assembled therein, so the durability of the roller is significantly inferior to that of a single rigid ball.

The ball gear cam 4 as described above has excellent processing productivity and has excellent durability because it uses a ball that is a rigid body rather than a roller, and has an effect of enabling a compact configuration because the diameter of the turret may be small.

Hereinafter, a processing method of the ball gear cam will be described.

Cam diagram definition step (step 1),

7 is a relationship diagram (cam diagram) and an assembly relationship diagram between the ball gear cam and the turret rotation angle.

As shown, the design principle of the ball gear cam at this stage adopts a cam diagram, which is a relational equation for the rotation angle of the cam and the rotation angle of the turret in the assembled state of the cam and turret (see Fig. 3). The rotation angle of the bolt turret corresponding to the rotation angle needs a cam diagram with the relational expression shown below.

[Relationship]

Ball gear cam rotation angles corresponding to 0°, 2°, 47°, 105°, 251°, 313°, 358°, and 360° are available at 0°, 0°, 68°, 68°, 248 Cam diagrams with °, 248°, 180°, 180°

Fitting step (step 2),

8 is a cam curve diagram after fitting the cam diagram with a smooth MS curve.

As shown, the cam diagram of the ball gear cam needs to be transformed into a smooth curve for smooth driving. This is called fitting. The fitting method of the cam diagram may apply various principles, but in the present invention, one MS curve (modified sine curve) is applied, and since it is defined as in Equation 1, it is expressed as shown in the cam curve diagram of FIG.

(식1)

(Equation 1)

는 볼기어캠의 회전각이며

는 터렛의 회전각을 의미한다.here

Is the rotation angle of the ball gear cam

Means the turret rotation angle.

Rotation angle definition step (step 3)

9 is a relationship diagram representing the moment when the ball leaves the circumference of the cam.

라고 하면

는 (식2)와 같이 된다. 여기서

는 터렛(turret)의 중심에서 볼(ball) 중심까지의 거리이고,

는 볼의 반경이고, R은 캠의 최외곽 반경이며,

는 캠 중심과 터렛 중심간의 거리이다.The position of the angle at which the cam curve of FIG. 8 meets the outer circumference of the ball gear cam can be obtained as the position where the contact of the ball is separated, as shown in FIG. 9, and at this time, the rotation angle of the turret is

If you say

Becomes as (Equation 2). here

Is the distance from the center of the turret to the center of the ball,

Is the radius of the ball, R is the outermost radius of the cam,

Is the distance between the center of the cam and the center of the turret.

(식 2)

(Equation 2)

Ball gear cam circumference and cam curve definition step (step 4)

10 is a ball gear cam circumference and a cam curve diagram, and FIG. 11 is a completed ball gear cam curve diagram.

가 되는 영역에서 캠곡선이 형성되며, 터렛의 원주상에 회전 가능하도록 조립되어 있는 볼의 개수를 N개라고 하면 터렛 중심에서 볼 중심을 잇는 곡선 간격의 각도는 360°/N이 된다. 1개의 볼이 캠의 홈을 따라 회전운동을 하면 다른 볼도 동일한 회전운동을 하므로 여러 개의 캠곡선이 형성되어야 한다. 도 11은 터렛에 설치된 기준 볼의 시작 각도를

라 하고 도시한 것이다. As shown, the rotation angle of the turret is

The cam curve is formed in the area where is, and if the number of balls assembled so as to be rotatable on the circumference of the turret is N, the angle of the curved distance from the center of the turret to the center of the ball is 360°/N. When one ball rotates along the groove of the cam, the other ball performs the same rotational movement, so several cam curves must be formed. 11 shows the starting angle of the reference ball installed on the turret.

It is shown as.

Here, it can be seen that the cam curve of the ball gear cam is composed of curves lying in the cam circumference region, as shown in FIG. 11. In addition, the number of cam curves differs according to the size of the maximum rotation angle of the cam diagram. If the maximum rotation angle in FIG. 7 is 248°, as shown in FIG. 11, eight cam curves are placed on the circumference of the ball gear cam.

Calculating the turret rotation angle of the curve (step 5)

If 8 balls are installed on the turret, the ball gear cam can define 8 curves as described above.

Here, as shown in FIG. 11, the two curves on the right were moved 360° and sent to the left to give numbers from ① to ⑧.

는 i번째 곡선의 터렛 회전각이고,

와

은

번째 곡선의 터렛 회전각 범위로서 식 3으로부터 구할 수 있다.Accordingly, the cam curve Equation 1 can be separately calculated by separating it into eight, and by attaching an index i to each rotation angle, the cam curve of the i-th curve can be expressed as Equation 3 from FIG. 10. here

Is the turret rotation angle of the ith curve,

Wow

silver

The turret rotation angle range of the curve can be obtained from Equation 3.

(식 3)

(Equation 3)

Position coordinate value definition step (step 6)

12 is a state diagram of a 4-axis processing machine having a C-axis, and FIG. 13 is a geometrical assembly relationship between a ball gear cam and a turret.

In order to process the cam curve of Equation 3 on the circumference of the ball gear cam, the C-axis as shown in Fig. 12 is machined with a 4-axis machine capable of rotating.

4-axis machine means to use BC-type 5-axis machine's XYZ-axis and C-axis.

의 + 방향은 C-축과는 반대가 된다. 이 때 캠곡선의 표현으로 볼 중심의 위치 좌표값

는 식 4와 같이 표현할 수 있다. And the assembly relationship between the turret and the ball gear cam, as shown in Figs. 12 and 13, the direction of the C-axis is set based on the rotation of the tool axis, so the rotation direction of the work piece is opposite.

The + direction of is opposite to the C-axis. At this time, the position coordinate value of the center of the ball as an expression of the cam curve

Can be expressed as Equation 4.

(식 4)

(Equation 4)

Step of applying a double curve to the end of the cam curve (step 7)

14 is a principle diagram of applying a double curve at the end of a cam curve.

When the ball is operated by the rotation of the ball gear cam, a collision may occur at the moment when the ball advances and exits at the beginning and end of the cam curve. Therefore, there is a hassle of manual grinding of the end of the cam curve. In the present invention, a double curve is applied at the end of the cam curve to solve the problem in cam processing.

만큼 떨어져 있는 것을

만큼 더 떨어져 있는 것으로 수정하고 점진적으로 작아져 j1과 j2에서 연속하며 접하도록 하여 매끄러운 새로운 캠곡선을 생성하면 볼이 곡선부의 진입과 퇴출할 때 충돌을 피할 수 있음을 알 수 있다. 14 shows the principle of applying the double curve at the end of the cam curve. If Equation 4 is subdivided into fine sections, it can be defined as a connection of n points from j=1 to j=n. And the positions j1 and j2 of a certain section at both ends can be obtained, and the position of the cam curve from the center of the turret at the ends is

Far away

It can be seen that the collision can be avoided when the ball enters and exits the curved part by modifying it to be further apart and making it progressively smaller and making continuous contact at j1 and j2 to create a new smooth cam curve.

라고 하면

는 식 5로 정의할 수 있는데,

는 시작점에서의 거리이고

는 2중 곡선이 적용되는 구간의 거리이며,

는 미소요소 j에서의 곡선의 거리를 의미한다. 따라서 식 4에 식 5를 적용하면 식 4는 식 6과 같이 수정할 수 있다. 본 발명에서의 2중 곡선의 적용은 롤러기어캠의 곡선에서의 2중 곡선의 적용과는 확연히 차별화되는 부분이다.Here, the additional distance from the center of the turret to the center of the ball

If you say

Can be defined by Equation 5,

Is the distance from the starting point

Is the distance of the section to which the double curve is applied,

Means the distance of the curve at the microelement j. Therefore, if Equation 5 is applied to Equation 4, Equation 4 can be modified as Equation 6. The application of the double curve in the present invention is a part that is clearly differentiated from the application of the double curve in the curve of the roller gear cam.

(식 5)

(Equation 5)

(식 6)

(Equation 6)

The step of machining by rotating the workpiece by an additional angle (step 8)

15 is a principle diagram of processing so that the tangential direction of the C-axis and the direction of the tool axis are at a predetermined angle.

The ball gear cam is processed using a ball end mill tool. Since the radius of rotation of the tool at the end of the ball is zero, the circumferential speed becomes zero, so cutting does not occur and crushing occurs. Therefore, the machined surface has poor machining characteristics.

Therefore, in the present invention, the principle of machining by rotating the work piece by an additional predetermined angle is applied in order to prevent the end point of the tool from participating in the machining.

에 추가 회전각

을 식 7에 추가하여야 하고 X,Y,Z값도 C-축의 추가 회전에 의해 좌표변환되어야 한다. 따라서 식 6은 최종적으로 식 8로 변환된다. 여기서

는 i번째 캠곡선의 미소요소 j에서의 x-축 좌표값을 의미한다. 도 15에서 T는 C-축 방향에 대한 접선벡터이고 S는 공구축 방향벡터이다.That is, the direction of the tool axis is always kept at a certain angle with respect to the C-axis rotation at the machining position of the work piece 14. To maintain a certain angle as shown in Fig. 15, it is equivalent to the C-axis of Equation 6 doing

Angle of rotation added to

Is added to Equation 7, and the X, Y, and Z values must also be transformed by additional rotation of the C-axis. Therefore, Equation 6 is finally converted to Equation 8. here

Denotes the x-axis coordinate value at the minute element j of the i-th cam curve. In FIG. 15, T is a tangent vector with respect to the C-axis direction and S is a tool axis direction vector.

(식 7)

(Equation 7)

(식 8)

(Equation 8)

Position data setting step (step 9)

For 4-axis machining of the ball gear cam, a ball end mill tool is used, and the result of Equation 8 is a path that passes through the center of the ball end mill, so CL-data (cutter location data), which is the position data of the tool for machining, is shown below. It is expressed as Equation 9.

In general, in a machine tool, the coordinate axis of the tool axis is set as the Z-axis, but since the 4-axis machine applied in the present invention uses only the 4-axis using the 5-axis complex machine as shown in FIG. 12, the tool axis direction is X-axis. I set it as an axis.

(식 9)

(Equation 9)

1: Roller gear cam 2: Turret
3: Roller 4: Ball gear cam
5: Ball 6: Machining groove of roller gear cam
7: Ball gear cap machining groove 8: End mill tool
9: Ball end mill tool 10: Angular area with respect to the circumference of the ball gear cam
11: Moving cam curves of balls on the turret 12: Cam curve
13: spindle 14: workpiece
15: Turret rotation center (tool side direction vector)
16: Angle between the tangential direction to the C-axis and the direction of the tool axis
17: Tangential vector about C-axis

Claims (2)

The rotation angle of the ball turret corresponding to the rotation angle of the ball gear cam is the step of defining a cam diagram with the relation shown below (step 1),
[Relationship]
Ball gear cam rotation angles corresponding to 0°, 2°, 47°, 105°, 251°, 313°, 358°, and 360° are available at 0°, 0°, 68°, 68°, 248 Cam diagrams with °, 248°, 180°, 180°

The fitting step of transforming the cam diagram of the ball gear cam into a smooth curve by defining it in Equation 1 (step 2),
[Equation 1]

Is the rotation angle of the ball gear cam,

Is the rotation angle of the turret

The position of the angle where the cam curve meets the outer circumference of the ball gear cam is the rotation angle definition step defined by Equation 2 (step 3),
[Equation 2]

Is the rotation angle of the turret,

Is the distance from the center of the turret to the center of the ball,

Is the radius of the ball,
R is the outermost radius of the cam,

Is the distance between the center of the cam and the center of the turret

If the number of balls assembled so as to be rotatable on the circumference of the turret is N, the angle of the curve distance from the center of the turret to the center of the ball is defined as 360°/N. ),

The cam curve of the i-th curve is the step of obtaining the turret rotation angle of the curve defined by Equation 3 (step 5),
[Equation 3]

Is the turret rotation angle of the ith curve,

Wow

Is the rotation angle range of the ball gear cam of the i-th curve

The position coordinate value of the ball center is the step of defining the position coordinate value defined by Equation 4 (step 6)
[Equation 4]

Is the position coordinate value

Applying a double curve to the end of the cam curve defined by Equation 5 and Equation 6 to avoid collision when the ball enters and exits the curved part (step 7),
[Equation 5]

j=1 to j=n is defined as the connection of n points by subdividing Equation 4 into fine sections,
j1 and j2 are the positions of a certain section

Is the additional distance from the center of the turret to the center of the ball

Is the distance from the starting point

Is the distance of the section to which the double curve is applied

Is the distance of the curve at microelement j

[Equation 6]

The rotation angle at which the direction of the tool axis always maintains a constant angle with respect to the C-axis rotation at the machining position of the work piece 14 is defined by Equation 7, and the X, Y, and Z values are changed by the additional rotation of the C-axis. Ball gear cam 4-axis processing method, characterized in that it consists of a step (step 8) of rotating a workpiece whose value is defined by Equation 8 by an additional predetermined angle.
[Equation 7]

Is the additional rotation angle
[Equation 8]

The method of claim 1,
The position data of the tool is a ball gear cam 4-axis machining method, characterized in that the position data setting step (step 9) defined by Equation 9 is further added.
[Equation 9]

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