Testing method graphite electrode chaser

1 Measuring method of tooth profile half-angle

(1) Adjust the angle of the rudder plate of the Universal Tool-Measuring Microscope eyepiece to 0°.

(2) The operation of the Universal Tool-Measuring Microscope adopts the method of gradual approximation so that the two solid lines with an included angle of 60° of the double cross auxiliary line are both tangent to the tip circle of a certain tooth of the chaser under test.

(3) Rotate the steering wheel of the goniometer eyepiece while fine-tuning the x-axis or y-axis rudder disk of the Universal Tool-Measuring Microscope, so that the angle between the left boundary line of a certain tooth of the chaser under test in the eyepiece and the double cross auxiliary line is the left side line of the 60° solid line overlaps or parallel. Since the 1/2 line method cannot be used to determine the overlap of the two lines at this time, it is recommended to use the gap method to make the gap between the two lines evenly parallel. Get graphite electrodes related products.

(4) Record the reading of the rudder plate of the Universal Tool-Measuring Microscope angle measuring eyepiece at this time, and record it as the left half angle deviation value of the tooth profile α_i (i=1, 2, 3, ...).

(5) Use the same method as step (3) to measure the Universal Tool-Measuring Microscope angle measuring eyepiece when the two solid lines on the right side of a tooth of the chaser under test and the double cross auxiliary line at an angle of 60° are parallel to each other. The reading of the rudder disc is recorded as the the right half angle of the tooth profile of the deviation value β_i (i=1, 2, 3, ...).

(6) Repeat steps (3)~(5) to measure the deviation values of the left half-angle of the tooth profile and the right half-angle of the tooth profile to be detected within the measuring range of the chaser under test.

(7) The absolute value of the deviation value of all the left half angle of the tooth profile and the right half angle of the tooth profile should be within the specified error range, as shown in formula (2).

∣α_i∣ or ∣β_i∣≤specified error (i=1, 2, 3,...)   

（2）

2 Tooth height measurement method

(1) Adjust the angle of the rudder plate of the Universal Tool-Measuring Microscope eyepiece to 0°.

(2) The operation of the Universal Tool-Measuring Microscope adopts the method of gradual approximation so that the two solid lines with an included angle of 60° of the double cross auxiliary line are both tangent to the tip circle of a certain tooth of the chaser under test.

(3) Fix the x-axis rudder of the Universal Tool-Measuring Microscope without moving, and operate the y-axis rudder of the Universal Tool-Measuring Microscope with a step-by-step approach so that the dashed line on the x-axis of the double cross auxiliary line is tangent to the addendum circle of the measured tooth, and record y at this time The axis coordinate is y _{tooth height 1}.

(4) Fix the x-axis rudder of the Universal Tool-Measuring Microscope without moving, and operate the y-axis rudder of the Universal Tool-Measuring Microscope and the rudder of the angle eyepiece so that the dotted line on the x-axis of the double cross auxiliary line coincides with the bottom line of the teeth on both sides of the measured tooth to the greatest extent. The angle of the rudder disc of the Universal Tool-Measuring Microscope eyepiece should be between 9°27′30″ and 9°28′, and the y-axis coordinate at this time is recorded as y _{tooth height 2}.

(5) The tooth height of the measured tooth is the difference between the above two y-axis coordinates, as shown in formula (3).

y _{tooth height i} = y _{tooth height 1}-y _{tooth height 2} (i=1, 2, 3,...)              (3)

(6) Repeat steps (2)~(5), measure all the tooth height parameters of the detected teeth required by the chaser to be tested and compare them with the standard value. The absolute value of the difference should be within the specified error range, as shown in the formula (4) shown.

∣y _{tooth height i}-y _{standard tooth height}∣≤ specified error (i=1, 2, 3,...)

(4)

3 Measuring method of single-tooth pitch, 1-inch cumulative pitch, and 200 mm cumulative pitch of all inner teeth

(1) Adjust the angle of the rudder plate of the Universal Tool-Measuring Microscope eyepiece to 0°.

(2) The operation of the Universal Tool-Measuring Microscope adopts a stepwise approach to make the two solid lines with an included angle of  60° of the double cross auxiliary line are tangent to the tooth tip circle of a certain tooth of the chaser under test, and record the x-axis’ coordinates of the 

Universal Tool-Measuring Microscope at this time is x_i (i=1, 2, 3,...).

(3) Repeat steps (1)~(2) to measure all the tooth height parameters x_i within the measuring range of the chaser under test.

(4) For single tooth pitch, it should satisfy formula (5):

∣(x_i +1 -x_i)- standard pitch ∣ ≤ specified error (i = 1, 2, 3,...) (5)

(5) For 1 inch cumulative pitch, it should satisfy formula (6):

∣(x_i+4-x_i)-standard pitch×4∣≤ specified error (i= 1, 2, 3,...)

(6)

Take a 45-tooth chaser cutter for Ф700 mm (28 inches) T4L electrode as an example. Its total length is about 300 mm. The x-axis stroke of a general Universal Tool-Measuring Microscope is 200 mm. The medium method detects the cumulative pitch of all teeth within 200 mm.

4 Measuring method of tooth bottom width

The geometric meaning of the various pitch measurement parameters of the chaser is shown in Figure 2. However, because there are often arc transitions at the junction of the two ends and the tooth profile that cannot be avoided during the manufacturing process, the measurement accuracy compared with the aforementioned measurement parameters  is relatively low, so in the process of evaluating the quality of the chaser, the tooth bottom width parameter can be used as an auxiliary parameter to correct the tooth height parameter. The measurement method of tooth bottom width is as follows:

(1) Rotate the goniometer eyepiece rudder plate and fine-tune the x-axis and y-axis rudder plates of the Universal Tool-Measuring Microscope goniometer at the same time, so that there are two auxiliary lines on the left side of the width of the bottom of the tooth between two teeth of the chaser under test in the eyepiece. The solid line with an angle of 60° coincides with one side of the solid line. Since the 1/2 line method cannot be used to judge the overlap of the two lines at this time, the angle of the Universal Tool-Measuring Microscope eyepiece rudder disc can also be rotated by 30° at this time, use the y-axis dotted line of the double cross auxiliary line to judge the coincidence.

(2) Operate the x-axis and y-axis rudder of the Universal Tool-Measuring Microscope and the rudder of the angle eyepiece to make the x-axis dotted line of the double cross auxiliary line coincide with the bottom line of the tooth between the two teeth to the greatest extent, at this time the rudder of the Universal Tool-Measuring Microscope of the angle eyepiece The angle should be between 9°27'30" and 9°28'.

(3) Repeat steps (1)~(2) until there is no need to move the x-axis and y-axis rudder of the Universal Tool-Measuring Microscope. Only rotating the rudder of the angle eyepiece can realize the steps and (2) the azimuth auxiliary line and the quilt. Measure the coincidence of straight lines, and record that the x-axis coordinate of the Universal Tool-Measuring Microscope is x _left at this time.

(4) Use the same method as steps (1)~(3) to determine the intersection of the right boundary line of the tooth bottom width between two teeth of the chaser under test and the tooth bottom line, and record that the x-axis coordinate of the Universal Tool-Measuring Microscope is x _right.

(5) The width of the tooth bottom between the two measured teeth is the difference between the above two x-axis coordinates, as shown in formula (7):

x _{tooth bottom width i} = ∣x _left-x _right ∣ (i=1, 2, 3,...)                   (7)

(6) Repeat steps (1)~(5) to measure all the bottom width parameters of the detected teeth of the chaser to be tested and compare with the standard value. The absolute value of the difference should be within the specified error range.

5 Measuring method of addendum radius

Since the Universal Tool-Measuring Microscope is only suitable for measuring the parameters in the straight line direction, the radius of the chaser tooth tip circle cannot be obtained by direct measurement, but the approximate data can be obtained by the geometric conversion relationship shown in Figure 4. The measurement method is as follows:

(1) Adjust the angle of the rudder plate of the Universal Tool-Measuring Microscope eyepiece to 0°.

(2) The operation of the Universal Tool-Measuring Microscope adopts the method of gradual approximation, so that the two solid lines with an included angle of 60° of the double cross auxiliary line are tangent to the tip circle of a certain tooth of the chaser under test, and the y-axis coordinate at this time is recorded as y _{Addendum circle 1}.

(3) Fix the x-axis rudder wheel of the Universal Tool-Measuring Microscope without moving, and operate the y-axis rudder of the Universal Tool-Measuring Microscope with a step-by-step approach to make the X axis dotted line of the double cross auxiliary line tangent to the addendum circle of the measured tooth, at this time record the y axis coordinate is y _{addendum circle 2}.

(4) The addendum radius of the tested tooth is the difference between the above two y-axis coordinates, as shown in formula (8).

y _{Addendum circle radius i} = y _{Addendum circle 1}-y _{Addendum circle 2} (i=1, 2, 3,...)

(8)

(5) Repeat steps (2)~(4) to measure all the tooth height parameters of the detected teeth required by the chaser to be tested.

The tip radius parameter is used to evaluate the wear degree of the chaser tooth tip and needs to be related to the tooth height parameter to judge the accuracy of the tooth height parameter measurement.

6 Chaser tooth angle

The arrangement direction of the chaser teeth of the chaser is not perpendicular to the upper and lower surfaces of the chaser. The oblique angle exists to prevent interference between the two teeth of the chaser due to the movement of the chaser during thread processing.

The measurement of the chaser-tooth oblique angle of the chaser cannot be measured by the Universal Tool-Measuring Microscope projection method, and the auxiliary lighting equipment of the Universal Tool-Measuring Microscope needs to be measured by the reflection method. Since there is no uniform standard for this parameter, it will not be repeated here.

7 Flatness of the upper and lower surfaces of the chaser

The flatness of the upper and lower surfaces of the chaser is used to evaluate the degree of deformation of the blade body after the chaser is sharpened. According to experience, due to the difference in the elastic modulus of the cemented carbide part and the ordinary steel part of the chaser, when the chaser is being repaired during grinding, due to the inconsistent recovery degree of the stressed material after extension, it is easy to cause the chaser to bend and deform. The flatness of the upper and lower surfaces of the chaser can be directly measured by the dial indicator of the plate and the slider, as shown in Figure 5.

Conclusion

The establishment of an evaluation and measurement system for graphite electrode thread chasers will help improve the processing quality of graphite electrode products, reduce quality accidents caused by electrodes in use, and reduce the manpower, material and financial input for this, as well as liability for breach of contract. The evaluation items and detection methods of thread chasers described in this article are based on years of research and practice on the machining accuracy of graphite electrodes, and they are highly maneuverable.