JPH0729243B2 - High-speed drum-shaped worm screw cutting machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high-speed hourglass worm threading machine.

(Prior Art) A drum-shaped worm screw cutting machine performs a swinging motion of a flat or bi-conical tool 1 around a wheel shaft 2 (center of table rotation) within a certain angle range (θ in FIG. 2) as shown in FIG. Had been done. However, this method has a drawback that the processing speed becomes slow. That is, high-speed tool steel is used for the tool, but 20-30m / mi
Since n is the limit, there is a limit to the speed. Therefore, cemented carbide can be used, but cemented carbide is expensive, and problems such as noise and heat generation occur when the rotation speed is increased. Therefore, only high speed tool steels can be used. Further, when it becomes a cemented carbide, there is a problem in workability, and manufacturing becomes difficult.

A conventional cylindrical worm high-speed screw cutting machine is such that a high-speed screw cutting attachment 7 is attached to a tool mounting base of the screw cutting machine 6 as shown in FIG. As shown in FIG. 4, this high-speed thread cutting attachment 7 is provided with at least one bite 9 on the inner ring of a bite holder 8 which is driven at high speed, and the inner ring is provided with a tilting center of the bite holder according to the advance angle of the worm screw.
It is designed so that it can be tilted around 10. And
As shown in FIG. 5, the outer periphery of the cylindrical worm material 4 that rotates at a low speed is eccentric to its axis and is cut when a bite 9 attached to a tool holder 8 that rotates at a high speed makes contact with the outer periphery of the cylindrical worm material 4 and is thin. Crescent-shaped chips are generated intermittently, and screws are created. Therefore, a screw with a coarse pitch can be completed with one cut.
However, since this is a cylindrical worm screw cutting machine, there is a problem that it cannot be used for drum-shaped worms.

(Problems to be Solved by the Invention) It is intended to increase the thread cutting speed of a drum-shaped worm to improve the production efficiency.

(Means for Solving the Problems According to the Invention) In a thread cutting machine that rotatably supports a work and performs thread cutting by moving a tool with respect to the work, a tool holder 11 to which a tool 12 of an inner blade is mounted is attached to one end. , Inclined surface by expanding the inner surface of the other end diagonally
Tool holder mounting base 13 designated as 13 ', a high-speed threading attachment body 15 in which the tool holder mounting base 13 is rotatably mounted via a bearing 16, and a tool provided in this attachment body 15 to obtain a desired lead angle. A high-speed threading attachment 7 comprising a holder tilting shaft 23, a support 18 for supporting the tool holder tilting shaft 23, and a power transmission unit 20, 21, 22 such as a belt for imparting rotation to the tool holder mounting base 13. And the support base 18 of the high-speed thread cutting attachment 7 is attached to the wheel shaft O by a swinging mechanism.
It is attached to the threading machine so that it can be swung around, so that the throat root of the worm and the cutting surface at the tip of the rotating surface of the cutting tool contact on the common perpendicular line of the worm shaft x ₁ and the wheel shaft O. The center section of the rotating surface of the cutting edge passes through the bite holder tilting shaft 23 and the wheel shaft O, and the bite holder tilting shaft 23 intersects with the wheel shaft O.

(Example) It demonstrates based on FIG. To summarize the present invention, the cutter head 3 of the conventional drum-shaped worm thread cutting machine shown in FIG.
The high-speed threading attachment 7 (see FIGS. 1 and 3).
The attachment 7 is attached to a drum-shaped worm threading machine so as to satisfy the following conditions.

First, as shown in Fig. 1, the high-speed thread cutting attachment 7 is a bite holder to which the rotating inner blade bite 12 is attached.
An annular tool holder mounting base 13 having an end 11 at one end and a high-speed thread cutting attachment body 15 rotatably supporting the mounting base 13 with a bearing 16 are provided. The high-speed thread attachment main body 15 has a pair of bite holder tilting shafts 23, 23 supported by a support 18 via bearings 19. The support 18 is attached to the threading machine so as to be swingable around the wheel axis O by a swing mechanism (not shown). The high-speed threading attachment main body 15 incorporates power transmission parts such as a motor 20, a pulley 21 and a belt 22 for rotating the bite holder mounting base 13 (see FIGS. 1, 3 to 5). When the inner blade bit 12 attached to the bit holder 11 rotates in the space together with the bit holder mounting base 13, the cutting edge of the inner blade bit 12 forms one surface in the space. Considering that it is a two-sided tool, attach the high-speed thread cutting attachment 7 to the drum-shaped worm thread cutting machine as follows. The bite holder mounting base 13 is formed by expanding the inner peripheral surface on the opposite side of the bite holder 11 toward the outer periphery to form an inclined surface 13 '.

B) On the common vertical line of the worm axis x _{1 of the} drum-shaped worm material 4 '(Fig. 1) and the wheel axis O (axis orthogonal to the x-axis and the y-axis), the throat root of the worm (the drum-shaped worm is , It has this name because it has a drum-like shape to a cylindrical worm, and the most constricted part of the drum is like the human body, called the throat, and the tip of the rotating surface (the rotation of the bite). The surface is a donut-shaped inverted conical surface, which is attached so that the cutting surface is in contact with the rotating surface of the tip of this cutter.

(B) Central cross section of the rotating surface of the cutting edge (the surface that is cut into circles so that the rotating surface is symmetrical (the center line of the cutting tool that passes through 1/2 of the cutting tool tip width and 1/2 of the rear end width) rotates with the cutting tool. The resulting surface, which results in a cross section that passes through the center of the rotating surface of the cutting edge, contains a common perpendicular (2 for solid gears).
The two gear axes are generally not parallel. It is twisted spatially. At this time, the only straight line that intersects each axis at right angles is obtained.

This is called the common perpendicular of the two gear shafts. At this time, innumerable planes including the common perpendicular are conceivable.
If a constraint is imposed such that the surface is orthogonal to the wheel axis O, the mounting is performed so that only the surface including the common perpendicular and orthogonal to the wheel axis can be obtained.

C) The central cross section of the rotating surface of the cutting tool edge passes through the tool holder tilting shafts 23, 23 and the wheel shaft O. That is, as one of the constituent requirements of the "high-speed thread cutting attachment 7", the tool holder tilting shafts 23, 2 provided on the high-speed thread cutting attachment main body 15 equipped with the tool holder mounting base 13 are previously mentioned.
Although the support base 18 for supporting the 3 through the bearing 19 is given, the center of the bite holder tilting shafts 23, 23 supported by the bearing 19 passes through X and Y in FIG.

In such a drum-shaped worm screw cutting machine, the rotation ratio of the tool table on which the worm blank 4'and the high-speed thread cutting attachment 7 are mounted is set to be equal to the desired reduction ratio to be obtained by this drum-shaped worm gear. . Further, the center distance between the wheel shaft O (center of rotation of the tool table) and the shaft center x ₁ of the drum-shaped worm blank 4'is set to a predetermined distance. Further, the high-speed thread cutting attachment main body 15 is tilted around the tool holder tilting shaft 23 according to the lead angle of the throat portion of the worm, and the motor 20 is rotated. As a result, power is transmitted to the pulley 21, the belt 22, and the pulley groove 14, and the bite holder mounting base 13 and the bite holder 11 start rotating integrally.

As a result, the cutting tool 12 of the inner blade forms a rotating surface, which is equivalent to replacing the rotating surface with a conventional conical cutter. By driving the screw cutting machine, the screw surface is cut on the hourglass-shaped worm blank 4 '. The root of the threaded surface thus corresponds to the desired worm threaded surface root. The thread groove is symmetrical with respect to the center of the groove.

(Effect) In a threading machine that rotatably supports a work and performs thread cutting by moving a tool with respect to the work, a tool holder 11 with a tool 12 of an inner blade is attached to one end, and Inclined side surface
13 'is a tool holder mounting base 13, a high-speed thread cutting attachment body 15 in which the tool holder mounting base 13 is rotatably mounted via a bearing 16, and a pair provided in the attachment body 15 to obtain a desired lead angle. Support 18 for pivotally supporting the tool holder tilting shaft 23, and a power transmission unit such as a belt for giving rotation to the tool holder mounting base 13.
A high-speed threading attachment 7 composed of 20, 21, 22 is provided, and the support base 18 of the high-speed threading attachment 7 is attached to a threading machine so as to be swingable around a wheel axis O by a swinging mechanism, and a worm shaft x ₁ The throat root of the worm and the cutting surface of the rotating surface of the cutting edge of the worm are in contact with each other on the common perpendicular line between the cutting tool and the wheel shaft. The tool holder tilt shaft 23 and the wheel shaft O intersect each other.

As a result, even in drum-shaped worm threading, high-speed threading similar to a cylindrical worm is possible.

[Brief description of drawings]

FIG. 1 shows the essential parts of a high-speed hourglass-shaped worm thread cutting machine according to the present invention. FIG. 2 shows a conventional drum-shaped worm thread cutting machine. Figure 3 shows a conventional cylindrical worm threading machine. FIG. 4 (a) is a high-speed thread cutting attachment, and FIG. 4 (b) is a side view of the same. FIG. 5 is an explanatory view of the cutting principle of the high speed screw cutting machine. In the figure; 1 ... Plane or double conical tool, 2 ... Wheel shaft 3 ... Cutter head, 4 ... Cylindrical worm material 4 '... Hourglass worm material, 5 ... Motor 6 ... Threading machine 7 ... High-speed thread cutting attachment 8 …… bite holder, 9 …… bite 10 …… bite holder tilt center, 11 …… bite holder 12 …… (inner blade) bite, 13 …… bite holder mounting base 13 ′ …… inclined surface, 14 …… Pulley groove 15 …… High-speed threading attachment body 16 …… Bearing, 17 …… Hole 18 …… Supporting base, 19 …… Bearing 20 …… Motor, 21 …… Pulley 22 …… Belt, 23 …… Bite holder Tilt axis

Claims (1)

[Claims] 1. A screw cutting machine for rotatably supporting a work and performing thread cutting by moving a tool with respect to the work, and a tool holder (11) having a tool (12) for an inner blade attached to one end thereof. Mounting, bite holder mounting base (13) with the inner surface of the other end expanded diagonally to form an inclined surface (13 '), and this bite holder mounting base (13) is rotatably mounted via a bearing (16). A high-speed threading attachment body (15), a pair of tool holder tilting shafts (23) provided on the attachment body (15) to obtain a desired lead angle, and the tool holder tilting shaft (23). Support stand (18) and tool holder mount (13)
A power transmission part (20,21,2
2) which comprises a high-speed threading attachment (7), wherein the support base (18) of the high-speed threading attachment (7) is swingable around a wheel shaft (O) by a swinging mechanism with respect to a threading machine. Mount the worm shaft (x ₁ ) on the common vertical line of the wheel shaft (O) so that the throat root of the worm and the cutting surface of the rotating surface of the cutting edge of the bite contact.
Further, the center section of the rotating surface of the cutting tool blade passes through the cutting tool tilting shaft (23) and the wheel shaft (O),
In addition, the high-speed drum-shaped worm screw cutting machine is characterized in that the bite holder tilting shaft (23) and the wheel shaft (O) intersect.