JPS5937173B2 - Variable gear ratio rack manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable gear ratio rack manufacturing apparatus.

One way to improve the steering characteristics of an automobile is to make the ratio of the angular displacement of the steering wheel relative to the rotation of the steering wheel relatively large in straight-ahead or near-straight steering conditions; When the steering wheel is deflected, there is a method of making the deflection angle of the steering wheel relative to the rotation of the steering wheel relatively small.

In order to do this, a rack in a steering rack-pinion mechanism consisting of a pinion driven by a steering wheel via a steering column and a rack that meshes with the pinion and is driven in the left-right direction by this pinion is used. It is necessary to configure it as a rack with variable gear ratio. A variable gear ratio rack for this purpose can be formed relatively easily by milling etc. when a spur gear is used as the pinion and its teeth are configured as straight teeth. When the teeth are made into spiral teeth such as helical teeth in order to make them smoother, it is technically impossible to form them by a normal cutting method such as milling.

On the other hand, for this type of variable gear ratio rack, there are infinite ways to change the gear ratio, and in order to find a preferable variable gear ratio among them, it is necessary to conduct experimental research on a large number of ways to change the gear ratio. What is desired is an apparatus that can easily manufacture a large number of variable gear ratio racks with various changes in the ratio. The present invention addresses the above-mentioned needs, and aims to provide a new device that can manufacture a variable gear ratio rack by setting the variable aspect of the gear ratio in any desired manner with a simple configuration. There is.

According to the present invention, such an object is to provide an electric discharge machine including a servo mechanism for moving a head for electric discharge machining in a direction along a first axis, and an electrical discharge machine having a servo mechanism for moving a head for electric discharge machining in a direction along a first axis; A transverse element is incorporated to be movable in a direction along a perpendicular second axis, and a pinion electrode for electric discharge machining is incorporated in the head to be rotated in response to movement of the transverse element. .

[having a spindle element configured as shown in FIG. The interlocking drive mechanism includes a cam and a cam follower, and by changing the shape of the cam, the transverse element is moved along the second axis relative to the movement of the head along the first axis. This is achieved by a manufacturing apparatus for a variable gear ratio rack, which is characterized in that it is configured such that it can be set in an arbitrary dependent relationship. The invention will now be described in detail by way of example embodiments with reference to the accompanying drawings.

FIG. 1 is an illustrative side view, partially in section, showing one embodiment of a variable gear ratio rack manufacturing apparatus according to the present invention.

In the figure, reference numeral 1 denotes a known electrical discharge machine, which is equipped with a servo mechanism that moves a movable head 2a, which conventionally directly supported an electrode for electrical discharge machining, in the direction of force along the first axis X. In the present invention, this moving head 2a
A head 2 incorporating a special feed correction mechanism described below is attached to the head 2, and is designed to drive the electric discharge machining electrode attached to this head. That is, when the electric discharge machining electrode attached to the head 2 and to which a positive voltage is applied comes into contact with a grounded workpiece, the servo mechanism senses a decrease in the potential difference therebetween and pulls the electrode away from the workpiece. Drive the heads in the direction of separation, forming an arc between them,
Furthermore, if the electrode is too far away from the workpiece and the arc is no longer maintained between them, the head is driven in the direction of bringing the electrode closer to the workpiece by sensing the increase in the potential difference between the two, and the head is finely adjusted. Therefore, a discharge arc is always maintained between the electrode and the workpiece, and the electrode functions to accomplish electrical discharge machining of the workpiece. In this case, the electrode for electrical discharge machining is a pinion-shaped electrode 3 shown in FIG. 2 and explained in more detail below, and the workpiece is an elongated material 4 formed as a rack. On the other hand, a rack 5 is built into the head 2 so as to be able to slide left and right as seen in FIG. It is.

Therefore, when the rack 5 is slid to the right or left in FIG. 1 with respect to the head 2, the pinion 6 is moved clockwise or counterclockwise around its axis as seen in FIG. Rotate. The pinion 6, as better shown in FIG. It's summery.

The head 2 is further provided with styluses 9 and 10 extending on both left and right sides thereof as viewed in FIG.

As schematically shown in FIG. 1, the stylus 9 includes a cylinder element 11, an arm 12 that engages the cylinder element like a piston, and is mounted within the cylinder element 11 and presses the arm 12 in the extending direction. The arm 12 includes a compression coil spring 13 and a screw element 14 for adjusting the spring force of the compression coil spring, and a pulley 15 and a cam driven roller 16 are provided at the tip of the arm 12 as better shown in FIG. It is being The stylus 10 also has a similar structure to the stylus 9, ie it has a cylinder element 17, an arm 18, a compression coil spring 19 and an adjusting screw 20. As for the stylus 9, a cam driven roller is not required at the tip of the arm 18, and it is sufficient to provide only the pulley 21. Further, as will be understood from the operation description below, the compression coil spring 19 in the stylus 10
It is configured to have a somewhat weaker spring force than the compression coil spring 13 in . Arm 1 next to stylus 9
A wire 23, which is fixed at one end to the end of the rack 5 and at the other end to the structural frame 22 of the device, is hung on the pulley 15 provided at the tip of the rack 2.

Similarly, a pulley 21 provided at the end of the arm 18 on the side of the stylus 10 has a wire 24 fixed at one end to the end of the rack 5 and at the other end to the structural frame 22 of the device. It is hung. The portions 23a and 24a of the wires 23 and 24 extending between the ends fixed to the structural frame 22 and the pulleys 15 and 21 are arranged to extend substantially parallel to the axis X. Also, the lengths of the wires 23 and 24 are such that when on the stylus 9 side its arm 12 extends beyond the cylinder element 11 to its maximum extent, on the stylus 10 side the arm 18 is within the cylinder element 17. It is determined that the cam is pushed in by the required amount in relation to the shape of the cam, which will be explained below. Cam driven roller 1 provided at the tip of arm 12
A cam 25 is provided at a position where it engages with cam 6.

In the illustrated example, the cam 25 has parallel parts at both ends.
It is made in a shape with a sloped part between the two heads.
moves downward in the figure, and the stylus 9 accordingly moves downward in the figure, the arm 12 does not initially move in the left-right direction in the figure, but only in the X direction, but at a certain point. From there, it gradually moves to the left in the figure along the Y-axis perpendicular to the X-axis, and then from a certain point it moves only in the X-direction again. In order to manufacture a variable gear ratio rack by electrical discharge machining the material 4 with the electrode 3 using such a device,
It is sufficient to start the discharging power recovery device 1 from the state shown in the figure.
As the material 4 is processed by the electrode 3 from one end thereof and a rack tooth is formed therein, the electric discharge machine 1 sequentially feeds the electrode 3 downward in the figure. At this time, as the head 2 moves downward in the figure, the wire 23 (here 23
Since the portion a increases and the portion 24a in the wire 24 decreases, the rack 5 is driven to the right in the figure, and the pinion 6 is driven clockwise in the figure. At the same time, the pinion-shaped electrode 3 is also driven to rotate in the same direction, and lock teeth are formed on the material 4 to mesh with the pinion. Cam follower 16 is part 25 of cam 25
Since the rotation of the pinion-like electrode 3 is proportional to the amount of feed of the pinion-like electrode 3 along the material 4 while engaged with the material 4, a rack tooth is formed on the material 4 with a certain constant gear ratio.

The head 2 further descends and the cam driven roller 16 moves to the cam 25.
When the arm 12 is engaged with the portion 25b, the arm 12 is driven to the left in the figure at a certain ratio to the feed amount of the head 2, and the rack 5 is correspondingly moved to the right in the figure. Since the amount is reduced, the amount of rotation of the electrode 3 relative to the amount of feed of the electrode 3 along the material 4 is reduced in a certain proportion. Therefore, the pitch of the rack teeth formed on the material 4 corresponding to this portion is larger than that of the rack teeth formed corresponding to the cam portion 25a. The head 2 further descends, and the cam driven roller 16 moves to the cam 25. When the electrode 3 engages with the third portion 25c, the amount of rotation relative to the feed amount of the electrode 3 along the material 4 becomes the same as that in the portion corresponding to the cam portion 25a, and the pitch of the rack teeth formed at this time is It is reduced to the original value again, that is, it becomes a rack tooth having the same shape as the rack tooth formed corresponding to the cam 25a. The variable gear ratio rack thus formed on the material 4 is a rack having a coarser pitch in its center than at its opposite ends. As is clear from the above description, when using the device of the present invention, by appropriately selecting the shape of the cam 25, it is possible to easily manufacture variable gear ratio racks in which the gear ratio changes in various ways. Can be done.

FIG. 4 is a perspective view showing another embodiment of the linear motion-to-rotation motion conversion mechanism using the rack 5 and pinion 6 in the embodiment shown in FIG.

In this embodiment, the rack 5 in the embodiment of FIG. 1 is eliminated, and the wire 23 including the portion corresponding to the rack is
A wire 26 corresponding to a wire made up of continuous wires 24 and 24 is wound around the spindle 7 several times. Even with this configuration, as the head 2 advances in the feeding direction, the wire 26 wound around the spindle 7 as a whole moves in the tangential direction with respect to the spindle, and accordingly, the spindle 7 It is rotated around its axis in the same manner as in the embodiment shown in FIG. In the case of this embodiment, a predetermined spiral groove 27 for guiding the wire 26 is formed around the corresponding portion of the spindle 7 in order to more securely attach the wire 26 to the spindle 7. preferable. FIG. 5 is a schematic partial cross-sectional view similar to FIG. 1 showing a third embodiment of the present invention, and FIG. 6 is a cross-sectional view taken along the line of FIG. 5.

In this embodiment, the spindle 7 carrying the electrode 3
is adapted to be rotationally driven by a belt 28 instead of the wire 26 in the embodiment shown in FIG. As better shown in FIG. 6, the spindle 7 is provided with a pulley portion 29 that engages with a belt 28, and the belt 28 is wound around approximately 3/4 of a portion of the pulley.
is fixed to the frame structure 22 at both ends thereof. The belt 28 wound around the pulley part 29 is tightly wound around the pulley part 29 by a pair of presser rollers 30 in a frictional engagement manner, thereby creating a gap between the spindle 7 and the belt 28. A slip-free engagement is achieved. A pair of presser rollers 30 each have an arm 31
These arms are each rotatably mounted on a shaft 33 fixed to the head 2 via roller bearings 32. These pair of arms 31 rotate the pair of rollers 30 in a direction toward each other by a pair of tension coil springs 35 that engage the arm at one end and engage a pin 34 attached to the head 2 at the other end. A spring force is applied in the direction of movement, which causes the belt 28 to move.
is held in tension. The belt 28 is further connected to the head 2
It is guided between rollers 36 and 37 which are rotatably mounted on the rollers 36 and 37.

A pair of rollers 36 and 37 are provided at both ends of the head 2, as shown in FIG. The belt 28, which is led out of the head 2 through the pair of rollers 36 and 37 on the right in FIG. guided upwards,
The upper end portion is fixed to the frame structure 22 as described above. Further, the belt guided between the pair of rollers 36 and 37 provided at the other end of the head 2 engages with a guide pulley 39 provided at the other end of the stylus, and is guided downward from this. , is fixed at its lower end to the frame structure 22 as described above. A groove 40 is cut in the upper part of the head 2, and a rail 41 is provided at the bottom of the groove.

A bar 43 having a pentagonal cross section as shown in FIG. 6 is slidably provided on this rail along its axis via rollers 42 constituting a roller bearing. This bar constitutes the aforementioned stylus. The cover 4 has slopes corresponding to the two slopes of the bar 43.
4 and which constitute a roller bearing are engaged with the rollers 45. The cover 44 is placed on the top of the head 2 via a disc spring 46, and is fastened to the head with bolts 47. An L-shaped member 48 is fixed to one end of the bar 43 (the right end in FIG. 5) with a nut 49, and the aforementioned guide roller 38 is rotatably mounted on the L-shaped member. , a cam driven roller 16 is rotatably mounted.

The main cam driven roller 16 performs the same function as the cam driven roller 16 in the embodiment shown in FIG.
A small diameter portion 43a is formed at the other end of the bar 43,
A flange 50 is attached to the stepped portion. This flange is slidably received in a cylinder hole 52 of a cylinder member 51 provided in a part of the head 2. An end cover 53 is attached to the open end of the cylinder hole 52 by screw engagement, and the small diameter portion 43a of the bar 43 extends through a hole 54 provided in the end cover 53.
A compression coil spring 55 is installed between the flange 50 and the end cover 53, and flexibly drives the spring 43 toward the end position of rightward movement as shown in FIG. ing. An arm 56 is fixed to the left end of the bar 43 in FIG. 5 by a nut 57, and the aforementioned guide roller 39 is rotatably supported at the lower end of the arm. As shown in FIG. 6, the spindle 7 is mounted on a ball bearing 5.
8 and 59), and is rotatably supported by the bolt 2, and is adapted to be rotationally driven by the belt 28 in the manner described above. 60 is a screw ring that holds the ball bearing 59 in the assembled position as shown, and 61 is a lock nut that maintains the installed position of the screw ring 60.

Further, 62 is a seal ring that closes the gap between the screw ring and the spindle 7. In this third embodiment as well, a cam 25 similar to the cam 25 provided in the embodiment shown in FIG. 1 is applied to the cam driven roller 16 in the manner shown in FIG. When the head 2 is lowered, the degree of rotation of the spindle 7 is adjusted according to the cam in the same manner as in the embodiment shown in FIG.
It will be clear that by varying the profile of 5, different variable gear ratio racks can be produced.

Although the present invention has been described above in detail with respect to one embodiment and some modifications thereof, those skilled in the art will recognize that various modifications can be made to this embodiment within the scope of the present invention. It should be obvious.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a partial cross section of an embodiment of a variable gear ratio rack manufacturing apparatus according to the present invention, and FIG. 2 shows a part of the apparatus shown in FIG. 1 in the direction of the arrow in FIG. 1. - Figure 3 is a view of a part of the apparatus shown in Figure 1 as seen in the direction of the arrow in Figure 1; Figure 4 is an example of a modification of the part of the apparatus shown in Figure 1. FIG. 5 is a schematic partially cross-sectional view of yet another embodiment of the variable gear ratio rack manufacturing apparatus according to the present invention, and FIG.
FIG. 1... Electric discharge machine, 2... Head, 3
... Electrode, 4 ... Material, 5 ...
・Rack, 6...Pinion, 7...Spindle, 8...Collection chuck, 9,10
... Stylus, 11 ... Cylinder element, 12 ... Arm, 13 ... Compression coil spring, 14 ... Adjustment screw, 15.・・・・・・
・Pulley, 16...Cam driven roller, 17...
...Cylinder element, 18...Arm, 19
...Compression coil spring, 20...Adjustment screw, 21...Pulley, 22...Frame structure, 23, 24...Wire, 25...Cam, 26...Wire, 27...Spiral groove, 28...Belt, 29...Roll portion, 30... ...Roller, 31...Arm,
32...Roller bearing, 33...Shaft, 34
...Pin, 35 ...Tension coil spring, 36, 37, 38, 39 ... Mouth ring, 40.
...Groove, 41...Rail, 42...
...Roller, 43...Bar, 44...Cover 45...Roller, 46...Disc spring, 47...Bolt, 48... L-shaped member, 49... Nut, 50... Flange, 51... Cylinder member, 52...
Cylinder hole, 53...End cover 54...
... Hole, 55 ... Compression coil spring, 56.
...Arm, 57...Natsuto, 58,5
9...Ball bearing, 60...Threaded sleeve, 61...Lock nut, 62...
·Seal ring.

Claims (1)

[Claims] 1. An electric discharge machine equipped with a servo mechanism that moves a head for electric discharge machining in a direction along a first axis, and a second axis within the head in a direction along a second axis substantially perpendicular to the first axis. a transverse element movably incorporated into the
a spindle element incorporated in the head to be rotated in response to movement of the transverse element and configured to carry a pinion electrode for electrical discharge machining; and movement of the head in a direction along the first axis. an interlocking drive mechanism that drives the transverse element in a direction along the second axis in response to A variable device characterized in that it is configured such that the movement of the transverse element in the direction along the second axis can be set in an arbitrary dependent relationship with respect to the movement of the head in the direction along the first axis. Gear ratio rack manufacturing equipment.