JPS6039022A - Barrel type built-up gear hob - Google Patents

Abstract

PURPOSE:To form a tooth profile, by rotating a spherical hob a turn as centering on the hob spindle center, while making a tooth into a state of being slipped as far as a portion for a pitch, as rotating the spherical hob in succession, and letting it engage an internal gear blank rotating synchronously with this. CONSTITUTION:In case of a barrel type built-up gear hob for forming an internal gear, as a result of finding a condition to materialize it as a built-up gear hob in the case where a relieving tooth profile 22 is formed out of a tooth profile 21 of a cutting edge face, it will do simply that a direction of interlocking for tooth profile relieving merely takes vartical with a hob spindle center 23. Next, a pitch circle diameter of the internal gear to be machined and a basic circle diameter are set down to dm and dg each, while a tooth top circle diameter of the internal gear to be machined is set so as to become more than {(dm- Dm)<2>sin<2>alpha-dg<2>}<1/2> when the pitch circle diameter of a virtual gear and its intermeshing pressure angle are set down to Dm and alpha each. Thus, a tooth profile can be formed in a state of being excellent in accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a barrel-type assembly hob for creating internal gears, and is particularly intended to be easily manufactured with good tooth profile accuracy.

A known hob for creating internal gears is a round ball-shaped hob disclosed in Japanese Patent Application Laid-Open No. 54-9089, and as shown in Figure 1(a), which shows its cross-sectional structure, the hob shaft The center 1 and the center of the pitch circle 4 of the tooth 3 along the cutting edge surface 2 intersect at a right angle. The teeth 3 formed in an involute tooth profile have a spiral shape, and as shown in FIG. 1(b), which shows the right side shape in FIG. The tooth profile of the tooth 3 is made to appear on the cutting edge surface 2 formed by the tooth 5.

Therefore, when the ball hob 6 is rotated once around the hob axis lt-, the phase is shifted by the pitch of the teeth 3Fi, and the internal gear that rotates synchronously with the ball hob 6 while continuously rotating the ball hob 6. By meshing with the material, tooth shapes can be created.

By the way, since the spherical hob 6 must have the characteristics of an involute gear in which the teeth 3 have a pitch circle 4, the top surface 7 of the teeth 30 and the left and right tooth surfaces 8 are provided with a relief amount (second cut). It is necessary to provide However, since the tooth 3 has a spiral shape, the relief amount of the left and right tooth flanks 8 is not the same on the left and right sides, and it is impossible to process them all at once. Therefore, the finishing of the teeth 3 of the spherical hob 6 is done on the top surface 7, the left tooth surface 8, the right tooth surface 8, the rounded part of the left tooth tip, and the rounded part of the right tooth tip. This has the disadvantage that it has to be processed separately, and it takes a lot of time to finish the teeth 3 compared to finishing the teeth of a normal hob.

Therefore, as shown in FIG. 2, the tooth 10 is
A barrel-type hob 12 is considered in which the center of the pitch circle 11 is offset by L. In other words, 1 ball 1 hob 6
Now, when this is sharpened with a blade, the diameter of the pitch circle 4 changes as the outer diameter decreases, so it is exactly the same as when the virtual gear 13 formed by the teeth 3 shifts in the negative direction. The ratio of change in the diameter of the pitch circle 4 must be designed so that the diameter of the pitch circle 4 is
In this barrel type hob 12, the amount of offset (offset) L may be changed, so even if the outer diameter decreases due to cutting, the diameter of the pitch circle 11 of the virtual gear 14 formed by the teeth 10 is kept constant and offset. It is also permissible to change L, increasing manufacturing tolerance. As a result, by making the diameter of the pitch circle 11 irrelevant to the decrease in the outer diameter of the barrel-type hob 12, it is possible to
It is only necessary to give the relief amount of the top surface 15 of 11O and the left and right tooth surfaces 16 in the same direction, and the manufacturing procedure is the same as that of a normal hob, so the finishing time of the teeth 10 is significantly shorter than that of the spherical hob 6. It is possible for women to be strong.

However, since these spherical hob 6 and barrel-type hob 12 have different outer diameters with the hob axis being 1.9Ka, the leading angle and second angle change accordingly, and the shape of the contact line with the grinding wheel remains constant. Furthermore, because this contact line is inclined with respect to the cutting edge surfaces 2 and 17, the timing of grinding between the tooth tip and the tooth base is shifted, and the movement of the second machining that advances during this shift is inaccurate. In some cases, tooth profile errors may occur. Therefore, the accuracy of the second cam of the grinding machine affects the tooth profile accuracy, and the difficulty of finishing the 3° lO tooth does not change at all.

Generally, the proportion of the contact line between the hob and the grinding wheel being inclined with respect to the cutting edge surface decreases as the diameter of the grinding wheel decreases, so a pencil-shaped grinding wheel is used as the tooth-shaped grinding wheel for the spherical hob 6 and barrel-shaped hob 12. are doing. However, the pencil-shaped whetstone has low grinding ability and is prone to wear, making it difficult to improve tooth profile accuracy. It's making it expensive.

From this point of view, the present invention takes into account the difficulties in manufacturing conventional spherical hobs and barrel hobs for creating internal gears.
It is an object of the present invention to provide a barrel type assembly hob having a new configuration that can improve tooth profile accuracy and is easy to manufacture.

In the conventional spherical hob and barrel type hob, as shown in FIG. In order to obtain the second tooth profile 20, it is not possible to obtain the required second tooth profile even if the blade is tilted forward like a normal hob and the tooth profile is ground. stomach. Therefore, in order to reduce the fluctuation of the tooth profile error by reducing the rate at which the second corner changes with respect to the hob axis, as shown in Fig. 3 Φ)K representing the concept of the second corner of the present invention. 1 Tooth profile of cutting edge 2! As a result of determining the conditions for establishing an assembled hob when the second tooth profile 22 is formed from
It is sufficient that the direction of the tooth profile reversing movement is perpendicular to the hob axis 28, and that the center 0 of the pitch circle 24 of the tooth virtual gear moves to KO' after the reversing machining.

In other words, the overall shape is a barrel-type hob, but the length of the hob is subject to some restrictions, as the angle between the tooth profile 21 and the direction of the second cut must always be a positive value. , if it is within these constraints, it can be used as an assembled hob.

In addition, in order to prevent involute interference between the tooth tip of the gear material and the root of the tooth profile 21 of the barrel-type hob, which occurs when the diameter of the inscribed gear material is too small, the tooth tip of the internal gear to be machined is Let the circle diameter, pitch circle diameter, and base circle diameter be df, dm, and dg, respectively, and the diameter of the pitch circle 23 of the virtual gear of the barrel type hob and its meshing pressure angle (tooth normal meshing pressure angle) f: Dm and a, respectively When
There needs to be a relationship between the virtual gear pitch circle diameter Dm and the pitch inner diameter dm of the internal gear to be machined.

On the other hand, it can be seen that the contact line between the second surface of the hob's tooth profile and the grinding wheel during tooth profile grinding is of great significance as a cause of the tooth profile error of the assembled hob due to the increase in lead angle. As shown in FIGS. 4(a) to (C) showing the state of this contact line, the contact angle of 526°27.28 with the edge of the cutting surface 25 where the tooth profile 21 appears is a pencil shape. Whetstone 2
9゜ dish-shaped whetstone 30. The size increases in the order of flat grindstone 31. Tooth profile error of the ground barrel-type assembly hob 4 Pencil-shaped grindstone 291 Dish-shaped grindstone 30. The size of the flat whetstone 31 increases in the order of size. Therefore, not only the angle of inclination of the contact line 28 formed by the flat grinding wheel 31 is extremely large, but also the contact line 28 is curved, making it difficult to improve tooth profile accuracy.
It is desirable to adopt 0 from the viewpoint of practicality, accuracy and efficiency.

In order to make the contact @27 by the dish-shaped grinding wheel 30 parallel to the edge of the cutting edge surface 25, it is sufficient to change the arrangement of the grinding wheel axis. surface(
(2) Align the axis parallel to the normal to the tooth profile 320 with the rotating axis of the 1-shape grindstone 30.

From the above, the configuration of the barrel-type assembled hob of the present invention that achieves the above-mentioned object is such that the center of the pitch circle of the virtual gear, which has a tooth profile along the cutting edge surface of the blade, is set at right angles to the hob center. The second surface of the blade is offset so that the line of contact between the second surface of the blade and the tooth profile machining tool is parallel to the green of the cutting surface, and the pitch diameter of the internal gear to be machined and When the base circle diameters are dm and dg, and the pitch circle diameter and meshing pressure angle of the virtual gear are Dm and α, respectively, the tip circle diameter of the internal gear to be machined is 5 colo = corro old. 7 bow r-dBν less □
It is characterized by having four settings.

According to the present invention, the grinding wheel shaft, which is arranged almost horizontally with respect to the barrel-type assembled hob, is displaced in the vertical direction according to the offset amount of the blade, and the grinding wheel shaft is rotated about the vertical plane around the grinding part of the grinding wheel. It is necessary to use a suitable grinding machine.

In a grinding machine with a structure like this, there is no need for a second pick-up motion, and the turning motion around the center of the virtual gear containing the tooth profile of the barrel-type assembly hob is simply performed in synchronization with the rotation of the barrel-type assembly hob. Good.

A grinding machine for a barrel-type assembled hob according to the present invention employing such a structure is shown in FIG. 5, and this grinding machine can be obtained by partially modifying a conventional hobbing machine.

An extension hob head 34 is attached to the illustrated hob head of a hobbing machine 33, and a barrel type assembled hob 36 of the present invention is attached to a hob shaft 35 which is driven and rotated in a state before tooth profile grinding. The counter column (not shown) is removed from the work slide 37, and the tool mount 3 is placed on the rotary table 38.
9 is installed in an adjustable manner, and a grindstone stand 40'f- is attached to this tool stand 39 which can be tilted in a vertical plane.

A grindstone spindle 41 having a pencil-shaped grindstone 29 is fixed to this grindstone stand 40 . rotary table 38
The center of the extended hob head 34 is aligned with the center of the virtual gear, and the extended hob head 34 is made to protrude significantly further than a normal hob head so that the center of the rotary table 38 can be moved to the required position relative to the barrel-type assembled hob 36. It is necessary to keep it.

Therefore, in order to set the line of contact between the pencil-shaped grinding wheel 29 and the tooth surface 32 of the barrel-shaped assembly hob 36 parallel to the edge of the cutting surface 25 of the blade, the grinding wheel head 40 can be tilted, and the barrel-shaped assembly hob 36 can be tilted. The offset between the hob axis of the hob 36 and the center of the pencil-shaped grindstone 29 can be easily and accurately provided by moving the extended hob head 34 in the vertical direction.

In this case, the rotary table 38 is the barrel type assembly hob 3
The pencil-shaped grinding wheel 29 rotates in synchronization with the rotation of the barrel-shaped assembly hob 36 in forward and reverse directions within a certain range of angles so as to reciprocate along the tooth grooves of the barrel-shaped assembly hob 36, thereby finishing into a predetermined tooth profile 21. .

Although the pencil-shaped grindstone 29 was used in the above embodiment,
It is also possible to use a dish-shaped grindstone 30, and as shown in FIG. A grindstone stand 42 that can be tilted up and down is installed.
A spindle holder 44 and a drive motor 45 are pivotally connected to the grindstone head 42 via a shaft 43, and are mounted in a 180-degree rotating structure so that the grinding surface of the dish-shaped grindstone 30 can be directed left and right. The dish-shaped grindstone 30 is driven by a drive motor 45 via a belt 46, and, like the pencil-shaped grindstone 29, performs highly efficient grinding.

In addition, if these grinders are modified to enable cutting by attaching end wheels, milling cutters, etc., they can also be used as a gear cutting device for pre-quenching materials of the barrel-type assembled hob 36. .

As described above, according to the barrel type assembly hob of the present invention, it is possible to easily and accurately grind the tooth profile, and it is possible to reduce costs.

[Brief explanation of drawings]

Figure 1(a) is a cutaway diagram showing the structure of the spherical hob.
]) is its right side view, Fig. 2 is a cutaway diagram showing the structure of the barrel-type hob, Fig. 3(a) is a principle diagram showing the concept of the conventional second hob, and Fig. 3) is the book. Fig. 4(a) is a conceptual diagram showing the contact state between the pencil-shaped grindstone and the tooth surface, and Fig. 4(a) shows the contact state between the dish-shaped grindstone and the tooth surface. Fig. 4(e) is a conceptual diagram showing the contact state between the flat grindstone and the tooth surface; Fig. 5 shows the external appearance of an embodiment of the grinding machine for finishing the barrel-type assembled hob of the present invention. The perspective view and FIG. 6 are plan views showing an example of a portion of a grindstone head for a dish-shaped grindstone. In the figure, 21 is a tooth profile, 23 is a hob axis, 24 is a pitch circle of a tooth profile, and 25 is a tooth profile. The cutting edge surface, 26 to 28 are the contact lines between the tooth surface and the grindstone, 29 is a pencil-shaped grindstone, 30 is a dish-shaped grindstone, 32 is the tooth surface, and is the center of the zero pitch circle. Patent applicant Mitsubishi Heavy Industries, Ltd. Patent attorney Shibe Mitsuishi (and 1 other person) Figure 1 (a) (b) 12 Figure 12 4 Figure 3 (a) (b) Figure 4 (G) (b ) 21 (c) Figure 5 137- 6th cause

Claims (1)

[Claims] The center of the pitch circle of a virtual gear having a tooth profile along the cutting edge surface of the blade is offset from the hob axis perpendicular to the center of the pitch circle, and the contact line between the second surface of the blade and the tooth profile processing tool is aligned with the cutting edge. The second surface is formed parallel to the edge of the surface, and the pitch circle diameter and base circle diameter of the internal gear to be machined are dm and dg, respectively, and the pitch circle diameter of the virtual gear and its meshing pressure When the angles are respectively b and a, the tip circle diameter of the internal gear to be machined is ηdm-D
m) A barrel-type assembly hob characterized by being set to be more than "sin'r-dg".