JPS62297701A - Tooth thickness measuring tool for gear - Google Patents

Abstract

PURPOSE:To measure tooth thickness with high accuracy by forming a couple of rack teeth with a specific pressure angle on a gauge main body, fitting a dial gauge on the opposite side from them, and projecting the measuring element to a bottom groove part between both rack teeth. CONSTITUTION:The rack teeth 2A and 2B which has the same pressure angle alphaas the pressure angle of a gear 11 to be measured are formed at one side part of the gauge main body 1. Their tooth surfaces 3A and 3B have their center parts 4 swelling in a horizontal sectional shape so as to improve the contacting between the gear 11 and tooth surfaces. Further, a through hole 5 is formed in the center of the opposite part of the main body 1, the dial gauge 6 is fitted in the hole 5, and the measuring element 7 is projected into the bottom groove part 8 between the teeth 2A and 2B. the measuring element 7, therefore, moves on a straight line running in the center of the gear 11. Thus, main body 1 and gear come into surface contact, so the tooth surfaces 3A and 3B hardly wear away and even if the pressing force of the gear 11 to the main body 1 varies depending upon a measuring person, there is a little influence upon the measuring element 7 and a high-accuracy measurement is taken.

Description

[Detailed description of the invention] 3. Detailed description of the invention Industrial applications The present invention relates to a gear tooth thickness measuring tool.

2. Description of the Related Art In general, methods for measuring the tooth thickness of gears include the straddle tooth thickness method, the overbin method, and the chord tooth thickness method using a tooth thickness caliper. Among these methods, the straddle tooth thickness method is often adopted because it has good measurement accuracy and is easy to measure. However, in the case of gears with a large helix angle and a narrow face width, the tooth thickness cannot be measured. In such cases, the thickness was measured by the chordal tooth thickness method using a tooth thickness caliper.

As shown in FIG. 4, this measurement method uses a tooth thickness caliper 21 to calculate the tooth height Hj (pre-calculated
1) and read the chord tooth thickness Sj at this location.

Problems to be Solved by the Invention According to the above-mentioned conventional tooth thickness caliper, measurement is carried out by contacting the probes 24A and 24B obliquely to the tooth surface (involute curve), so individual differences in measurement pressure and contact condition may occur. It is large and unsuitable for cases requiring high precision. Further, although the tips of the probes 24^ and 24B are quench-hardened, they are point contacts, and when a relatively high measurement pressure is repeatedly applied, they wear out, leading to a decrease in measurement accuracy.

Therefore, an object of the present invention is to provide a gear tooth thickness measuring tool that can solve the above problems.

Means for Solving the Problems In order to solve the above problems, the gear tooth thickness measuring tool of the present invention has a gauge body formed with a pair of rack teeth having a predetermined pressure angle, and a pair of rack teeth of the gauge body and a pair of rack teeth having a predetermined pressure angle. In this case, a dial gauge is attached to the opposite side, and the measuring point of this dial gauge is made to protrude into the root groove between both rack teeth.

Operation First, a reference pin having a diameter of about 1/2 of the normal pitch of the measuring gear is brought into contact between the rack teeth of the gauge body, and the measurement r of the dial gauge is applied to the outer peripheral surface of the reference pin to obtain the gauge reading at this time. Adjust to 0 points.

Note that the chord tooth height and chord tooth thickness of the reference tooth corresponding to this reference pin are known in advance, and the displacement of the measuring tip of the dial gauge when the reference tooth is inserted is also known. After the above-mentioned zero point adjustment, the teeth of the measuring gear to be actually measured are inserted between the tooth surfaces of the gauge body, and the displacement of the measuring tip is read with a dial gauge. Then, find the difference between this read displacement and the displacement when a previously known reference tooth is inserted, and adjust the chord tooth thickness of the base 7 < gear tooth according to this difference. Thickness can be determined.

EXAMPLE Hereinafter, an example of the present invention will be explained based on FIGS. 1 to 3.

Reference numeral 1 denotes a gauge body, and a pair of rack teeth 2A, 2B having a predetermined pressure angle (the same pressure angle as the pressure angle of the measurement gear) α are formed on the negative side thereof.

The rack teeth 2A, 2B have tooth surfaces 3A, 3B formed only in the portions facing each other, and in order to make good contact with the tooth surface of the measuring gear, as shown in FIG. , the central portion 4 is swollen in the horizontal cross-sectional shape. Further, a through hole 5 is formed in the center of the opposite side of the gauge body 1 from the rack teeth 2A, 2B, and a dial gauge 6 is attached to this through hole 5.
The measuring tip 7 of this dial gauge 6 is designed to protrude from the through hole 6 into the tooth bottom groove 8 between both the tooth cavities 2A and 2B. Of course, the measuring stylus 7 of the dial gauge 6 is configured to move on a straight line passing through the center of the measuring gear.

Next, the measurement method will be explained.

First, as shown in FIG. 3, the reference pin 12 having a diameter d of approximately /2 of the normal pitch of the measuring gear 11 is brought into contact between the rack teeth 2A and 2B of the gauge body 1, and the dial gauge 6 is The gauge reading at this time is adjusted to 0 point by applying the measuring tip 7 to the outer peripheral surface of the reference pin 12.

Note that the chord tooth height Ho and string tooth thickness So of the reference tooth 13 corresponding to this reference pin I2 are known in advance, and from these values, the displacement i of the measuring stylus 7 of the dial gauge 6 when the reference tooth 13 is inserted is determined. I also understand.

That is, the displacement i can be calculated using the following formula.

, d X c o s a S o + H. h2X
tanα However, h='XdX (1-sinα).

In the formula, d: Diameter of the reference pin α: Pressure angle After the above zero point adjustment, as shown in FIG.
, 3B, and read the displacement (■) of the probe 7 using the dial gauge 6. And this read displacement V,
By finding the difference from the displacement i when the reference tooth 13, which is known in advance, is inserted, and correcting the chord tooth thickness So of the reference tooth 13 according to this difference, the chord tooth thickness S of the measurement gear 11 can be accurately determined. be able to.

According to this measuring tool, the depth of cut of the tool can be directly read during gear cutting using a rack-type tool (such as a hob). In other words, with other measurement methods, the depth of cut must be converted from the tooth thickness reading, but
When using this measuring tool, the difference in tooth depth above a certain value (difference between displacements Vi) is equal to the tool depth of cut.

Effects of the Invention According to the tooth thickness measuring tool of the present invention, the tooth of the measuring gear is inserted between the rack teeth of the gauge body and the position of the tooth tip is measured by the dial gauge. Since the contact point changes from the conventional point contact to a surface contact, there is almost no wear on the tooth surfaces of the rack teeth, which serve as the measurement reference surface of the gauge body, and the pressing force of the measuring gear against the gauge body changes depending on the operator. However, the dial gauge has almost no effect on the contact point of the dial gauge, and therefore highly accurate measurements can be made.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention.
The figure is a partially cutaway front view of the tooth thickness measuring tool, and Figure 2 is I of Figure 1.
-I sectional view, Figure 3 is a front view of main parts explaining the measurement method,
FIG. 4 is a front view of a conventional measuring instrument. 1... Gauge body, 2A, 2B... Rack teeth, :3
A. 3B...Tooth surface, 6...Dial gauge, 7...Measuring point, 8...Tooth bottom groove

Claims (1)

[Claims] 1. Form a pair of rack teeth with a predetermined pressure angle on the gauge body, attach a dial gauge to the opposite side of the gauge body from the rack teeth, and insert the gauge head of this dial gauge into the bottom of the teeth of both rack gears. A gear tooth thickness measuring tool characterized by protruding into a groove.