JPS6161722A - Method of cutting teeth of timing gear - Google Patents

Abstract

PURPOSE:To enhance the accuracy of timing of gears, by aligning a rotation locking and engaging element for a set of gears with a rotation locking and engaging element fitted onto an arbor to assemble the arbor with the set of gears so that a tooth cutting process carried out satisfying a specific formula with respect to a predetermined angle. CONSTITUTION:An angle between both engaging elements is set at 90 deg. upon assembling and using of rotors 16, 16' and keys 13, 13' which are attached to gears. The tooth number Z of gears 10, 10' is set to Z which is calculated with the use of the formula alpha=180(Zn-1)/Z where alpha=90 deg. and an arbitrary integer number n=12. In a tooth cutting method, a set of gear blanks 1, 1' are arranged a back-to-back relation, that is, short boss sections 9a, 9a' are faced to each other while long boss sections 9b, 9b' are made remote from each other, and attached to an arbor 4. Further, the key section is formed such that a key 8 is fitted in a key groove 5 formed in the arbor 4. Furthermore, the one set of gear blanks 1, 1' are simultaneously formed with teeth 11, 11' at a tooth number of Z=46 by cutting to produce gear 10, 10'.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for cutting gears for a set of mechanical elements that require mutual rotational timing, and relates to a method for cutting gears for a timing gear, such as a pair of roots-type gears. It is used for the timing of compressors, pumps, and expanders equipped with rotors, and generally for the timing of all rotating mechanical elements that require rotational timing.

(Prior Art) In general, in a set of timing gears using spur gears, for example, the angular position of rotation fixing means such as a keyway and the angular position of teeth that define the rotation angle with the shaft are respectively A predetermined relationship is required in the gears.

Conventionally, the gears were first cut, and then the keyway was machined by determining the position of the keyway relative to the center of the tooth groove or tooth ridge as a reference.

(Problems to be Solved by the Invention) However, according to this conventional processing method, the accuracy of the keyway position relative to the teeth is very poor because it is difficult to accurately center the tooth crest or tooth groove. Therefore, the timing imbalance of the gears deteriorates, and for example, in a Roots-type compressor, the gap between the rotors widens, resulting in increased leakage and problems such as not being able to achieve a predetermined discharge performance.

The present invention solves the drawbacks of the prior art described above.
The technical problem is to provide a t'ia cutting method that improves the precision of the relationship between the seedling and the gear teeth and improves the timing accuracy of the gear.

[Structure of the invention]

(Means to resolve problem 1a!) Kieda i・)・〒To achieve the above problem, method 1; 1, arbor and 8 sets of gears are matched, and for a predetermined angle α, α=180(
2n-1)/Z (where α is the angle between the base elements, Z is the number of teeth, and n is any positive multiple) when using the gear assembly.

(Function) According to the above technical means, firstly, a set of gears has a rotationally fixed I
Since the IN@ element is processed and assembled into the rotary fixed engagement element installed in the arbor, the gear machining standard can be easily achieved with this double rotation fixed engagement element.

Based on this integrated element with good integration and fixed 1 system! Since gear cutting is performed on a set of four gears at the same time, it is important to have high timing accuracy between each gear.

Here, if we reduce the product angle of 111° for a set of gears, we get
Since each gear shifts by half a pitch, the angle shifts by (360/Z) x 1/.

Adding the timing angle α to this, it is sufficient that each gear is in the same phase, so α+ (360/Z) XI/2= (3(i0/Z)
It is sufficient if it is xn. That is, α=180 (2n-1)/Z.

(Example) The present invention will be explained below based on examples.

FIG. 1 shows the rotating parts of a roots-type compressor, with a shaft 15.
15', a rotor 16.16' fixed to this shaft 15.15°, and the same Φ as the rotor 16.16'
Mountain shaft 15. ], 5” (Key 13.13°
It consists of a gear 10,10'' fixed at a rotor 16,
16° and the timing angle α of the keys 13 and 13″ are set to 90°.
If α=180(2n −1)/Z, α=90. It is set to Z-.16 calculated as n=12.

The gear cutting method for this gear 10,10' is carried out as follows.

As shown in FIG. 2, a shaft fitting hole 2 and a key groove 3, which is a rotationally fixed engagement element, are formed in a gear material 1. This full-key machining provides a better finish than machining at least one set of gears at the same time or machining each gear individually.

Next, as shown in FIG. Assemble the long boss parts 9b and 9b' with the long bosses 9b and 9b' facing each other as shown in 5.1.In addition, even if the gear material is symmetrical on the front and back, such as when the length of the hub is the same, it is better to consider back-to-back alignment. This affects the accuracy when assembling the product.Furthermore, the key part of the arbor 4, which is a rotationally fixed engagement element, is formed by fitting a key 8 into a key groove 5 provided in the arbor 4. A portion of this key is formed of a single member so that the keyways 3, 3'' of at least one set of gear materials 1, 1'' are assembled at the same position in the circumferential direction.Although not shown in the figure, the gear The materials 1, 1'' are fixed to the arbor 4 by fixing means so that they do not move in the upper axial direction of the arbor 4.

In the above state, at least one set of gear elements (first,
At the same time, machine the lo with a gear cut of 11.11” at Z=46,
Gear 10.10' is manufactured.

〔Effect of the invention〕

To achieve the object of the present invention, Japanese Patent Application Laid-Open No. 59-5931
The method disclosed in Publication No. 5 has also been considered. However, although this method is effective over the conventional technology, it is necessary to process the individual keyways for assembling a set of gears into the arbor with their phases shifted. 11'i processing is troublesome, and an error of +1 rJ degree may occur between 111 and L1.

In contrast, in the present invention, since only one key is required to be added to the arbor, machining is easy, and since the keys are assembled back to back, accuracy errors do not occur.

In addition, especially when using spline means 33.33'' as a rotationally fixed locking element as shown in FIG.
No. 5931.5 (spline using the technique of 7??,
It is very difficult to process the gears 30, 30' into an arbor out of phase with the individual gears 30, 30'. On the other hand, if the present invention is used, a full -thread spline is sufficient.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the main rotating parts of a roots type compressor that can be assembled with a set of gears according to the present invention, Fig. 2 is a diagram of the gear material according to the present invention, and Fig. 3 is a gear cutting process of a set of gears according to the present invention. Fig. 4 is another example of Fig. 1. 1.1°...gear material, 3. 3', 8.33.
33゛... Rotating fixed locking element, 4... Arbor, 1
0.10', 30.30'...Gear 14th 1s2

Claims (1)

[Scope of Claims] A method for cutting a set of gears including rotary fixed engagement elements for mounting on a shaft at a predetermined angle α to each other, wherein the rotary fixed engagement elements provided on the arbor include the The arbor and the set of gears are assembled by matching the rotary fixed engagement elements of the set of gears, and for the predetermined angle α, α=180(2n-1)/Z (however, α is the angle between both engaging elements when the gear is assembled and in use, Z is the number of teeth, and n is any positive integer.