Worm shaft machining device and method for compound hourglass worm gears

Abstract

The present invention provides an apparatus and method for machining a worm shaft of a double enveloping worm gear consisting of a worm shaft and a worm wheel, and is characterized by the fact that the worm shaft can be moved in the X-axis, the worm machining cutter can be moved in the Y-axis and Z-axis, the worm shaft can be rotated in the A-axis, the cutter can be rotated in the C-axis, and the shaddle on which the cutter is installed can be tilted in the B-axis, making the worm shaft machining process easy.

Description

[Technical Field]

[0001] The present invention relates to a device and method for machining a worm shaft of a compound hourglass worm gear, and more particularly to a device and method for machining a worm shaft of a compound hourglass worm gear, which can easily perform a thread machining process on a worm shaft having a compound hourglass shape. [Background technology]

[0002] Generally, the power transmission system of a power transmission device mainly uses gears with teeth that utilize an involute curve, which is the path that the tip of a wound thread traces when it is unwound in a taut state.

[0003] Such gears have teeth formed on a circumference, and are devices that transmit rotation or power by meshing gears formed on the circumference between two or more shafts. When gears are used, power or rotation can be transmitted reliably and at an accurate angular velocity ratio.

[0004] Such gear types include spur gears, helical gears, bevel gears, and worm gears.

[0005] In particular, worm gears have a significantly larger gear ratio than general gears, and are special gears in which the input and output directions of power form a right angle.

[0006] In the case of a power transmission device composed of a worm gear, the worm shaft is rod-shaped, while the worm wheel that meshes with and comes into contact with the teeth of the worm shaft is disk-shaped, and the teeth of the worm shaft are formed at intervals along the circumference, which reduces the mutual contact area between the worm shaft and the worm wheel, i.e., reduces the meshing ratio.

[0007] In such existing worm shafts and worm wheels, the contact area of ​​the meshing teeth is narrow, and pressure on the gear teeth is localized, resulting in high pressure and low torque, which reduces the efficiency of the worm and worm gear.

[0008] That is, there are problems such as a decrease in the efficiency of the output rotational force, a decrease in the durability and lifespan of the gear teeth, a decrease in shock resistance, and an increase in noise and vibration.

[0009] To overcome this problem, a double-hour shaped worm shaft, such as a Hindley Worm, is known as a power transmission device.

[0010] A compound drum worm shaft has a compound drum-shaped curve on its outer surface, with spiral grooves, for example spiral teeth, formed in the curved area. The worm wheel that meshes with it has a large number of teeth, so the area that supports the pressure between the teeth is larger than that of a normal worm gear. This reduces gear wear and allows for the transmission of large power.

[0011] However, conventional power transmission devices are limited to use with such compound hourglass worm gears, and are unable to fully utilize the characteristics of the compound hourglass worm shaft and use it with gears of various shapes.

[0012] In addition, the gear teeth of the existing compound drum-shaped worm shaft are also configured with a convex shape tooth form, and are not configured in a form that is wrapped around the circumferential contact surface of the worm wheel, which reduces the contact ratio. Also, since the contact area is narrow, pressure on the gear teeth is localized and high, resulting in low torque and poor efficiency.

[0013] Furthermore, when machining such compound hourglass worm gears, there is a problem in that it is not possible to automatically machine the diameter that gradually increases from the central axis to the outside, or to machine the lead angle formed by each worm pitch, using a general worm machining device.

[0014] Furthermore, the central axis rotates during machining, and even if mechanical control is used, this type of machining can cause problems such as the torque from the mechanical operation causing the rotation to be pushed during cutting, resulting in errors.

[0015] As described above, the compound hourglass worm gear has the advantage of being capable of high torque acceptance, high load capacity, and highly efficient power transmission. However, as mentioned above, there are many problems in processing it using conventional techniques, and precision work cannot be performed, so technological development is urgently needed. Summary of the Invention [Problem to be solved by the invention]

[0016] The present invention has been devised based on the above-mentioned technical background, and its object is to provide an apparatus and method for machining the worm shaft of a compound hourglass worm gear, which can easily and accurately perform the worm shaft machining process of a compound hourglass worm gear.

[0017] Another object of the present invention is to provide an apparatus and method for machining a worm shaft for a compound hourglass worm gear, which allows for X-axis movement of the worm shaft, Y-axis and Z-axis movement of the worm machining cutter, A-axis rotation of the worm shaft, C-axis rotation of the cutter, and B-axis tilting of the saddle on which the cutter is installed, thereby facilitating the worm shaft machining process.

[0018] Another object of the present invention is to provide an apparatus and method for machining a worm shaft of a compound hourglass worm gear that is capable of removing burrs by a plunging action.

[0019] Another object of the present invention is to provide an apparatus and method for machining a worm shaft of a compound hourglass worm gear, which is capable of forming a lead angle on the worm shaft by tilting the saddle about the B axis.

[0020] Furthermore, the object of the present invention is not limited to the above-mentioned object, and other objects not mentioned above will be clearly understood from the following description. [Means for solving the problem]

[0021] In order to achieve the above object, the present invention provides an apparatus for machining a worm shaft of a double enveloping worm gear, which is composed of a double enveloping worm shaft and a worm wheel, comprising: an A-axis spindle for rotating the worm shaft around the X-axis, which is the longitudinal direction; an X-axis table provided with a support that can move in the X-axis direction according to the length of the worm shaft; a worm machining cutter installed so that a cutter blade faces the cutting surface of the worm shaft; a saddle having a C-axis spindle for rotating the worm machining cutter around the Z-axis; a column provided to allow the saddle to move in the Z-axis direction; and a support member provided at the bottom of the X-axis table and column, which supports the X-axis table and the worm shaft. and a bed provided to allow movement of the axis table in the X-axis direction and movement of the column in the Y-axis direction. When the number of teeth of the worm machining cutter and the number of teeth of the worm wheel are the same, the A-axis spindle and the C-axis spindle rotate at a speed ratio determined by the ratio of the number of teeth of the worm machining cutter and the number of teeth of the worm wheel, and the worm shaft and the worm machining cutter rotate. The column advances in the Y-axis direction and the worm machining cutter enters the worm shaft. Machining begins as the tip diameter of the worm machining cutter enters the root diameter of the worm shaft. The column then moves backward in the Y-axis direction and the saddle rises in the Z-axis direction, causing the worm machining cutter to move backward and upward. The column then advances again in the Y-axis direction and the worm machining cutter enters the worm shaft. After that, the saddle descends in the Z-axis direction and the worm machining cutter descends, thereby machining the worm shaft.

[0022] According to a preferred embodiment of the present invention, the saddle further includes a B-axis saddle block that is tilted about the Y-axis.

[0023] Further, in order to achieve the above object, the present invention provides an apparatus for machining a worm shaft of a compound-hungry worm gear composed of a compound-hungry worm shaft and a worm wheel, the apparatus comprising: an A-axis spindle for rotating the worm shaft around the X-axis which is the longitudinal direction; an X-axis table provided with a support that can move in the X-axis direction according to the length of the worm shaft; a worm machining cutter installed so that a cutter blade faces the cutting surface of the worm shaft; a C-axis spindle for rotating the worm machining cutter around the Z-axis; and a saddle block tiltable around the Y-axis. a saddle including a block; a column provided to allow the saddle to move in the Z-axis direction; and a bed provided under the X-axis table and the column to allow the X-axis table to move in the X-axis direction and the column to move in the Y-axis direction. When the number of teeth of the worm machining cutter is less than the number of teeth of the worm wheel, the A-axis spindle and the C-axis spindle rotate at a speed ratio determined by the ratio of the number of teeth of the worm machining cutter to the number of teeth of the worm wheel, and the worm shaft and the worm machining cutter rotate. The column advances in the Y-axis direction and the worm machining cutter enters the worm shaft, and machining begins as the tip diameter of the worm machining cutter enters the root diameter of the worm shaft. At the same time, the X-axis table moves in the X-axis direction, and the worm shaft moves in the X-axis direction, and the worm machining cutter moves to the PCD (Pitch Circle Distance) of the worm wheel. The worm shaft is machined while being moved along an arc formed along the center of the PCT of the worm machining cutter and the diameter of the saddle, and the worm machining cutter is machined as the saddle descends in the Z-axis direction and the worm machining cutter descends, and the rotation direction of the worm machining cutter and the movement direction of the worm machining cutter can be the same direction or opposite directions.

[0024] According to a preferred embodiment of the present invention, the X-axis table further includes a first transfer device connected to the support to move the support in the X-axis direction, and a first encoder and a first linear scale capable of precisely controlling the movement of the support.

[0025] According to a preferred embodiment of the present invention, the bed further includes a second transfer device connected to the X-axis table to move in the X-axis, a second encoder and a second linear scale capable of precisely controlling the movement in the X-axis, a third transfer device connected to the column to move in the Y-axis, and a third encoder and a third linear scale capable of precisely controlling the movement of the column.

[0026] According to a preferred embodiment of the present invention, the column further includes a fourth transfer device connected to the saddle to move in the Z-axis direction, and a fourth encoder and a fourth linear scale capable of precisely controlling the movement of the saddle.

[0027] Meanwhile, to achieve the above object, the present invention provides a worm shaft machining method using a compound-hung worm gear worm shaft machining device, comprising the steps of: rotating the A-axis spindle and C-axis spindle to rotate the worm shaft and the worm machining cutter at a speed ratio determined by the ratio of the number of teeth of the worm machining cutter to the number of teeth of the worm wheel; the column advances in the Y-axis direction, causing the worm machining cutter to enter the worm shaft, with the tip diameter of the worm machining cutter entering the root diameter of the worm shaft to begin machining; the column moves backward in the Y-axis direction, while the saddle rises in the Z-axis direction, causing the worm machining cutter to move backward and upward; the column advances again in the Y-axis direction, causing the worm machining cutter to enter the worm shaft to perform machining; and the saddle moves downward in the Z-axis direction, causing the worm machining cutter to descend to perform machining.

[0028] In order to achieve the above object, the present invention provides a worm shaft machining method using a worm shaft machining device for a compound hourglass worm gear, comprising the steps of: rotating the A-axis spindle and C-axis spindle to rotate the worm shaft and the worm machining cutter at a speed ratio determined by the ratio of the number of teeth of the worm machining cutter to the number of teeth of the worm wheel; moving the column in the Y-axis direction so that the worm machining cutter enters the worm shaft and the tip diameter of the worm machining cutter enters the root diameter of the worm shaft to begin machining; simultaneously moving the X-axis table in the X-axis direction so that the worm shaft moves along the X-axis, and machining is performed while the worm machining cutter is transported along an arc formed along the center of the PCD of the worm wheel and the PCD of the worm machining cutter; and lowering the column in the Z-axis direction so that the worm machining cutter descends to perform machining. [Effects of the Invention]

[0029] The present invention having the above-described configuration is expected to have the following effects.

[0030] This has the effect of enabling the worm shaft of a compound hourglass worm gear to be machined easily and precisely.

[0031] That is, the worm shaft can be moved in the X-axis direction while rotating on the X-axis and A-axis, the cutter can be moved in the Y-axis and Z-axis directions while rotating on the Y-axis and C-axis, which are perpendicular to the X-axis, and the cutter can be tilted around the B-axis, which is perpendicular to the A-axis and C-axis, respectively, so the worm shaft machining process can be easily performed.

[0032] In this case, the A-axis rotation, X-axis movement, C-axis rotation, and Y-axis movement can be synchronized and controlled, which has the effect of easily machining the worm shaft depending on the size of the cutter.

[0033] In addition, plunging in the Z-axis direction is possible, making it easy to remove burrs, and the lead angle of the worm shaft can be set by tilting around the B-axis, making it easy to perform precise machining as needed. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a perspective view showing a worm shaft machining device for a compound hourglass worm gear according to a preferred embodiment of the present invention; FIG. [Figure 2] 1 is a simplified diagram showing the internal structure of an X-axis table, a bed, and a column of a worm shaft machining apparatus for a compound hourglass worm gear according to a preferred embodiment of the present invention. FIG. [Figure 3] 1 is a cross-sectional view showing a worm shaft and a worm machining cutter in a worm shaft machining device for a compound hourglass worm gear according to a preferred embodiment of the present invention, in which the number of teeth of the cutter is the same as the number of teeth of the worm wheel. [Figure 4] FIG. 4 is a diagram showing the progress of machining in FIG. 3. [Figure 5] 1 is a cross-sectional view showing a worm shaft and a worm machining cutter in a worm shaft machining device for a compound hourglass worm gear according to a preferred embodiment of the present invention, in which the number of teeth of the cutter is less than the number of teeth of the worm wheel. FIG. [Figure 6] FIG. 6 is a diagram showing the progress of machining in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0035] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to the description, advantages, features, and methods of achieving the present invention will become apparent from the following detailed description of the embodiments together with the accompanying drawings. The terms used in this specification are intended to describe the embodiments and are not intended to limit the present invention. It is understood that singular terms include plural terms unless otherwise specified, and that directional words used in the description are intended to facilitate understanding of the description and may be changed at any time.

[0036] A worm shaft machining device for a compound hourglass worm gear according to a preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 is a perspective view showing a worm shaft machining device for a compound hourglass worm gear according to a preferred embodiment of the present invention;

[0037] The X-axis, Y-axis, and Z-axis are defined by the coordinates shown in the figure, and the axis that rotates around the X-axis is defined as the A-axis rotation, the axis that rotates (or tilts) around the Y-axis is defined as the B-axis rotation (or B-axis tilt), and the axis that rotates around the Z-axis is defined as the C-axis rotation.

[0038] Referring to FIG. 1, the worm shaft machining device 100 for a compound hourglass worm gear according to the present invention rotates and moves a worm shaft 60 while machining it using a rotating and moving cutter 33, and includes an X-axis table 10, a worm machining cutter 20, a saddle 30, a column 40, and a bed 50.

[0039] The X-axis table 10 is a table on which a worm shaft 60 for machining is fixed and rotated, and includes an A-axis spindle 11 that rotates the worm shaft 60 around the X-axis, which is the longitudinal direction, and a support 13 that is provided on the X-axis table 10 and can move in the X-axis direction according to the length of the worm shaft 60.

[0040] That is, the worm shaft 60 rotates about the X-axis by the A-axis spindle 11, and rotates about the A-axis. Here, the A-axis rotation is synchronized with the C-axis rotation, which will be described later.

[0041] In addition, the worm shaft 60 is fixed by a support 13 and chuck jaws 15, and as shown in the figure, the worm shaft 60 is fixed on one side by the chuck jaws 15, and rotational force is provided by the A-axis spindle 11, while on the other side it is rotated and fixed by a tailstock structure equipped with a support 13 that supports the center point of the rotating worm shaft 60.

[0042] Here, the support 13 can move along the X-axis along the rails on the X-axis table 10, and the support 13 is moved along the X-axis along the rails to match the length of the worm shaft 60 for machining, and the worm shaft 60 is fixed.

[0043] A first transfer device is provided for moving the support 13 along the X axis, and an example of such a first transfer device is shown in Figure 2. Figure 2 is a simplified diagram showing the internal structure of the X-axis table, bed, and column of a worm shaft machining device for a compound hourglass worm gear according to a preferred embodiment of the present invention.

[0044] Referring to FIG. 2, the X-axis table 10 includes a nut 61 connected to the support 13, a ball screw 62 connected to the nut 61 to move the support 13 along the X-axis, a motor 63 for driving the ball screw 62, and a coupling 65 connecting the ball screw 62 and the motor 63. The X-axis table 10 also includes an encoder 64 and a linear scale 67 that can measure the displacement of the support 13 and perform precise control.

[0045] The first transfer device according to the present invention is not limited to the above-described configuration, and the configuration for linearly moving the support 13 in the X-axis direction can be any form, and the nut and ball screw in the above-described configuration may be removed and driven by a linear motor.

[0046] Here, the linear scale 67 is a device that measures the amount of movement of the support 13 along the X axis and provides feedback. If movement of the support 13 along the X axis is required, the support 13 is moved by the ball screw 62 and nut 61 driven by the encoder 64 and motor 63, and the linear scale 67 confirms the position of the support 13. If the position differs from the position to which the support 13 should be moved, the linear scale 67 corrects the error value and performs feedback control.

[0047] In addition, the support 13 does not have a separate power source but is rotatable, and has a tapered end and a sharp tip, so that it is supported in contact with the center of the other end surface of the worm shaft 60.

[0048] Next, the saddle 30 is equipped with a worm machining cutter 20 for machining the worm shaft 60, and includes the worm machining cutter 20 installed so that the cutter blade faces the cutting surface of the worm shaft 60, a B-axis saddle block 33 tilted around the Y-axis, and a C-axis spindle 31 that rotates the worm machining cutter 20 around the Z-axis.

[0049] The worm machining cutter 20 is mounted on a C-axis spindle 31 that rotates around the Z-axis, rotates about the C-axis, and is mounted on a saddle block 33 so that the cutter blade faces the cutting surface of the worm shaft 60 as shown in the figure.

[0050] Here, the saddle block 33 is "L" shaped, and as shown in the figure, the horizontal side is provided in the Y-axis direction, and the C-axis spindle 31 is provided on the underside of the horizontal side so that it faces downward, and the cutter blade of the worm processing cutter 20 faces the cutting surface of the worm shaft 60.

[0051] Here, the shape of the saddle block 33 is not limited to being "L"-shaped, and any shape is possible as long as the saddle block 33 allows the worm machining cutter 20 to face the cutting surface of the worm shaft 60 and the worm machining cutter 20 to tilt along the B axis.

[0052] The vertical side of the saddle block 33 is provided in the Z-axis direction, and is provided on the column 40, and is particularly provided on the saddle 30 so as to be tilted about the Y-axis, that is, the B-axis.

[0053] That is, the saddle block 33 is mounted on the saddle 30 so that the C-axis spindle 31 can rotate about the Z-axis and tilt about the Y-axis, ie, the B-axis.

[0054] Next, the column 40 is provided to allow the saddle 30 to move in the Z-axis direction, and a rail is provided on the front surface of the column 40, so that the saddle 30 can move in the Z-axis direction along the rail.

[0055] A fourth transfer device is provided to move the saddle 30 in the Z-axis along the rails of the column 40. As shown in FIG. 2, the column 40 includes a nut 61 connected to the saddle 30, a ball screw 62 connected to the nut 61 to move the saddle 30 in the Z-axis, a motor 63 to drive the ball screw 62, a coupling 65 connecting the ball screw 62 and the motor 63, and an encoder 64 and a linear scale 67 that can measure the movement displacement of the saddle 30 and perform precise control.

[0056] Here, like the first transfer device described above, the fourth transfer device is not limited to the configuration shown in FIG.

[0057] Next, the bed 50 is provided below the X-axis table 10 and the column 40, and allows the X-axis table 10 to move in the X-axis direction and the column 40 to move in the Y-axis direction.

[0058] That is, the bed 50 has rails on the top in the X-axis direction to allow the X-axis table 10 to move in the X-axis direction, and has rails on the top in the Y-axis direction to allow the column 40 to move in the Y-axis direction.

[0059] For this purpose, a second transfer device is provided, and as shown in FIG. 2, bed 50 includes a nut 61 connected to X-axis table 10, a ball screw 62 connected to nut 61 to move X-axis table 10 along the X-axis, a motor 63 for driving ball screw 62, a coupling 65 connecting ball screw 62 and motor 63, and an encoder 64 and linear scale 67 for measuring the displacement of X-axis table 10 and enabling precise control.

[0060] Here, like the first transfer device described above, the second transfer device is not limited to the configuration shown in FIG.

[0061] The bed 50 also includes a third transfer device connected to the column 40, and this third transfer device includes a nut 61, a ball screw 62 connected to the nut 61 to move the column 40 in the Y-axis direction, a motor 63 that drives the ball screw 62, a coupling 65 that connects the ball screw 62 and the motor 63, and an encoder 64 and a linear scale 67 that measure the movement displacement of the column 40 and enable precise control.

[0062] Here, like the first transfer device described above, the third transfer device is not limited to the configuration shown in FIG.

[0063] A worm shaft machining method using the compound hourglass worm gear worm shaft machining device according to the present invention will now be described.

[0064] The worm shaft machining device for a compound drum-shaped worm gear according to the present invention can perform machining in two ways: when the number of teeth on the worm machining cutter is the same as the number of teeth on the worm wheel, or when the number of teeth on the worm machining cutter is less than the number of teeth on the worm wheel.

[0065] First, a method for machining a worm shaft of a compound hourglass worm gear according to the present invention will be described in the case where the number of teeth of the worm machining cutter and the number of teeth of the worm wheel are the same.

[0066] FIG. 3 is a cross-sectional view showing a worm shaft and a worm machining cutter in a worm shaft machining device for a compound drum worm gear according to a preferred embodiment of the present invention, when the number of teeth on the cutter is the same as the number of teeth on the worm wheel, and FIG. 4 is a diagram showing the machining progress state in FIG. 3.

[0067] That is, referring to FIG. 3, in a worm gear constituted by a worm shaft 60 and a worm wheel, the worm shaft 60 is machined using a worm machining cutter 20 having the same size as the worm wheel.

[0068] In the drawing, the tip diameter is the tooth tip diameter of the worm machining cutter 20, the root diameter is the root diameter of the worm shaft 60, and the axial distance is the distance between the centers of the worm wheel, i.e., the center of the worm machining cutter 20 and the center of the worm shaft 60.

[0069] Referring to Figures 1 to 4, first, the A-axis spindle 11 and the C-axis spindle 31 rotate at a speed ratio determined by the ratio between the number of teeth of the worm machining cutter 20 and the number of teeth of the worm wheel, causing the worm shaft 60 and the worm machining cutter 20 to rotate.

[0070] Next, the column 40 advances in the Y-axis direction, and the worm machining cutter 20 enters the worm shaft 60 as shown in Figure 4 (1). The tip diameter of the worm machining cutter 20 enters the root diameter of the worm shaft 60, and machining begins.

[0071] Next, the column 40 moves backward in the Y-axis direction while the saddle 30 moves upward in the Z-axis direction, and the worm machining cutter 20 moves backward and upward as shown in Fig. 4(2). That is, it moves upward obliquely backward.

[0072] Next, the column 40 moves forward again in the Y-axis direction, and the worm machining cutter 20 advances into the worm shaft 60 to perform machining, as shown in FIG. 4(3).

[0073] Next, the saddle 30 is lowered in the Z-axis direction, and the worm machining cutter 20 is lowered to machine the worm shaft 60, as shown in FIG. 4(4).

[0074] In this way, the worm shaft 60 and the worm machining cutter 20 rotate, and the worm machining cutter 20 advances in the Y-axis direction to begin machining, then the worm machining cutter 20 moves backward and upward in an oblique direction, and then advances again in the Y-axis direction before descending axially along the Z-axis, thereby machining the worm shaft 60.

[0075] Here, the downward movement of the worm machining cutter 20 in the Z-axis direction is for machining the worm shaft 60 and for plunging and removing the unmachined area.

[0076] That is, burrs generated by the machining process according to the present invention can be easily removed through the plunging action, and machining can be performed without leaving any unmachined areas.

[0077] In addition, the saddle block 33 can be tilted around the B axis, and a lead angle can be formed on the worm shaft 60 through the tilting movement of the saddle block 33 .

[0078] That is, as shown in FIG. 4(1) above, when the worm machining cutter 20 advances, the saddle block 33 is tilted by the lead angle to be machined on the worm shaft 60, and then the worm machining cutter 20 advances to machine the worm shaft 60, forming a lead angle on the worm shaft 60 and allowing machining to be performed.

[0079] Here, the tilting operation of the saddle block 33 may be omitted, but this is because the cutter blade of the worm machining cutter 20 is formed at an angle corresponding to the lead angle to machine the worm shaft 60.

[0080] In this case, machining can be performed while forming a lead angle on the worm shaft 60 even without tilting the saddle block 33.

[0081] Furthermore, if the number of teeth of the worm machining cutter 20 and the number of teeth of the worm wheel are the same, the movement of the X-axis table 10 in the X-axis direction does not proceed.

[0082] On the other hand, a method for machining a worm shaft of a compound hourglass worm gear according to the present invention will be described below when the number of teeth on the worm machining cutter is less than the number of teeth on the worm wheel.

[0083] FIG. 5 is a cross-sectional view showing a worm shaft and a worm machining cutter in a worm shaft machining device for a compound drum worm gear according to a preferred embodiment of the present invention, when the number of teeth on the cutter is less than the number of teeth on the worm wheel, and FIG. 6 is a diagram showing the machining progress state in FIG. 5.

[0084] That is, referring to FIG. 5, in a worm gear formed by a worm shaft 60 and a worm wheel, the worm shaft 60 is machined using a worm machining cutter 20 smaller in size than the worm wheel.

[0085] In the drawings, PCD stands for pitch circle diameter, and the transfer path of the worm machining cutter 20 can be determined using the PCD of the worm wheel and the PCD of the worm machining cutter.

[0086] In other words, when the number of teeth on the worm machining cutter is less than the number of teeth on the worm wheel, in addition to the forward and backward movement and up and down movement of the worm machining cutter 20, it must be moved along an arc along the cutting surface of the worm shaft 60. During such arc movement of the worm machining cutter 20, the arc is moved along an arc formed along the center of the PCD of the worm wheel and the PCD of the worm machining cutter 20.

[0087] Referring to Figures 1, 5 and 6, first, the A-axis spindle 11 and the C-axis spindle 31 rotate at a speed ratio determined by the ratio between the number of teeth on the worm machining cutter 20 and the number of teeth on the worm wheel, causing the worm shaft 60 and the worm machining cutter 20 to rotate.

[0088] Next, the column 40 advances in the Y-axis direction, and the worm machining cutter 20 enters the worm shaft 60 as shown in Figure 6 (1). The tooth tip diameter of the worm machining cutter 20 enters the root diameter of the worm shaft 60, and machining begins.

[0089] Here, the distance between the tooth tip diameter of the worm machining cutter 20 and the root diameter of the worm shaft 60 is the same as the distance between the aforementioned contact points between the PCD of the worm wheel and the PCD of the worm machining cutter 20.

[0090] At the same time, the X-axis table 10 moves in the X-axis direction, the worm shaft 60 moves in the X-axis direction, and the worm machining cutter 20 is moved along an arc formed along the center of the PCD of the worm wheel and the PCD of the worm machining cutter 20, thereby performing machining.

[0091] Such a transfer of the worm machining cutter 20 is illustrated by the arrow D in FIG.

[0092] In this way, the X-axis movement of the X-axis table 10, the Y-axis movement of the worm machining cutter 20, the A-axis rotation of the worm shaft 60, and the C-axis rotation of the worm machining cutter 20 are all performed simultaneously.

[0093] Next, the saddle 30 is lowered in the Z-axis direction, and the worm machining cutter 20 is lowered to machine the worm shaft 60, as shown in FIG. 6(2).

[0094] Here, the downward movement of the worm machining cutter 20 in the Z-axis direction is for machining the worm shaft 60 and for plunging and removing the unmachined area.

[0095] In addition, a lead angle can be formed on the worm shaft 60 by tilting the saddle block 33 around the B axis, or the cutter blade of the worm machining cutter 20 can be formed at an angle corresponding to the lead angle to machine the worm shaft 60, so that machining can be performed while forming a lead angle on the worm shaft 60 even without tilting the saddle block 33.

[0096] Also, the direction of movement of the worm machining cutter 20 may be opposite to that of the arrow D.

[0097] The above description merely exemplifies the technical concept of the present invention, and those skilled in the art may make various modifications, changes, and substitutions without departing from the essential characteristics of the present invention. As described above, the embodiments and accompanying drawings disclosed in the present invention are for illustrative purposes only, and are not intended to limit the technical concept of the present invention. The scope of the technical concept of the present invention should be interpreted by the following claims, and all technical concepts within the scope of the claims should be interpreted as being within the scope of the present invention. [Explanation of symbols]

[0098] 100 Compound Hourglass Worm Gear Worm Shaft Processing Device 10 X-axis table 11 A-axis spindle 13 Support 15 chuck jaws 20 Worm machining cutter 30 Saddle 31 C-axis spindle 33 Saddle Block 40 columns 50 beds 61 Nut 62 Screw 63 Motor 64 Encoder 65 Coupling 67 Linear Scale

Claims

1. An apparatus for machining a worm shaft of a double enveloping worm gear, the worm shaft being composed of a double enveloping worm shaft and a worm wheel, comprising: an A-axis spindle that rotates the worm shaft around the X-axis, which is the longitudinal direction, and an X-axis table that is provided with a support that can move in the X-axis direction according to the length of the worm shaft; a saddle having a worm machining cutter with a cutter blade facing the cutting surface of the worm shaft and a C-axis spindle that rotates the worm machining cutter around a Z-axis; a column configured to allow the saddle to move in the Z-axis direction; a bed provided below the X-axis table and column, the bed being configured to allow the X-axis table to move in the X-axis direction and the column to move in the Y-axis direction; When the number of teeth of the worm machining cutter and the number of teeth of the worm wheel are the same, When the A-axis spindle and the C-axis spindle rotate at a speed ratio determined by the ratio of the number of teeth of the worm machining cutter to the number of teeth of the worm wheel, the worm shaft and the worm machining cutter rotate, The column advances in the Y-axis direction, and the worm machining cutter enters the worm shaft. Machining begins when the tip diameter of the worm machining cutter enters the root diameter of the worm shaft. The column moves backward in the Y-axis direction, while the saddle moves upward in the Z-axis direction, and the worm machining cutter moves backward and upward, After the column advances again in the Y-axis direction and the worm machining cutter enters the worm shaft, 1. A worm shaft machining device for a compound hourglass worm gear, wherein the saddle is lowered in the Z-axis direction and the worm machining cutter is lowered to machine the worm shaft.

2. The saddle is 2. The apparatus for machining a worm shaft of a compound hourglass worm gear according to claim 1, further comprising a B-axis saddle block tilted about a Y-axis.

3. An apparatus for machining a compound-hung worm shaft of a compound-hung worm gear composed of a compound-hung worm shaft and a worm wheel, an A-axis spindle that rotates the worm shaft around the X-axis, which is the longitudinal direction; and an X-axis upper axis table that is provided with a support that can move in the X-axis direction according to the length of the worm shaft; a worm machining cutter installed so that a cutter blade faces the cutting surface of the worm shaft; a C-axis spindle for rotating the worm machining cutter around a Z-axis; and a saddle including a saddle block tilted around a Y-axis; a column configured to allow the saddle to move in the Z-axis direction; a bed provided below the X-axis table and column, the bed being configured to allow the X-axis table to move in the X-axis direction and the column to move in the Y-axis direction; When the number of teeth of the worm machining cutter is less than the number of teeth of the worm wheel, When the A-axis spindle and the C-axis spindle rotate at a speed ratio determined by the ratio of the number of teeth of the worm machining cutter to the number of teeth of the worm wheel, the worm shaft and the worm machining cutter rotate, The column advances in the Y-axis direction and the worm machining cutter enters the worm shaft, and machining begins as the tooth tip diameter of the worm machining cutter enters the root diameter of the worm shaft. At the same time, the X-axis table moves in the X-axis direction, the worm shaft moves in the X-axis direction, and the worm machining cutter moves along an arc formed along the center of the PCD (Pitch Circle Diameter) of the worm wheel and the PCD of the worm machining cutter, thereby performing machining; The saddle is lowered in the Z-axis direction, and the worm shaft is machined while the worm shaft is lowered. The worm shaft machining device for a compound hourglass worm gear is characterized in that the rotation direction of the worm machining cutter and the transfer direction of the worm machining cutter can be the same direction or opposite directions to each other.

4. The X-axis table is a first transfer device connected to the support and adapted to move in the X-axis direction; 4. The worm shaft machining device for a compound hourglass worm gear according to claim 1 or 3, further comprising a first encoder and a first linear scale capable of precisely controlling the movement of the support body.

5. The bed is a second transfer device connected to the X-axis table to move the table along the X-axis; a second encoder and a second linear scale capable of precisely controlling the movement of the X-axis table; a third transfer device connected to the column to move it in the Y-axis direction; 4. The worm shaft machining device for a compound hourglass worm gear according to claim 1 or 3, further comprising a third encoder and a third linear scale capable of precisely controlling the movement of the column.

6. The column comprises: a fourth transfer device connected to the saddle for Z-axis movement; 4. The worm shaft machining device for a compound hourglass worm gear according to claim 1, further comprising a fourth encoder and a fourth linear scale capable of precisely controlling the movement of the saddle.

7. A worm shaft machining method using the worm shaft machining device for a compound hourglass worm gear according to claim 1, The A-axis spindle and the C-axis spindle rotate at a speed ratio determined by the ratio of the number of teeth of the worm machining cutter to the number of teeth of the worm wheel, thereby rotating the worm shaft and the worm machining cutter; The column advances in the Y-axis direction, and the worm machining cutter enters the worm shaft, and machining begins while the tip diameter of the worm machining cutter enters the root diameter of the worm shaft; the column moves backward in a Y-axis direction while the saddle moves upward in a Z-axis direction, and the worm machining cutter moves backward and upward; The column advances again in the Y-axis direction, and the worm machining cutter enters the worm shaft to perform machining; and a step of lowering the saddle in the Z-axis direction and lowering the worm machining cutter while machining.

8. A worm shaft machining method using the worm shaft machining device for a compound hourglass worm gear according to claim 3, comprising: The A-axis spindle and the C-axis spindle rotate at a speed ratio determined by the ratio of the number of teeth of the worm machining cutter to the number of teeth of the worm wheel, thereby rotating the worm shaft and the worm machining cutter; The column advances in the Y-axis direction, and the worm machining cutter enters the worm shaft, and machining begins while the tip diameter of the worm machining cutter enters the root diameter of the worm shaft; At the same time, the X-axis moves in the X-axis direction, the worm shaft moves in the X-axis direction, and the worm machining cutter is moved along an arc formed along the center of the PCD of the worm wheel and the PCD of the worm machining cutter, thereby performing machining; and a step of lowering the column in the Z-axis direction and lowering the worm machining cutter to perform machining.

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