Measuring and testing – Frictional resistance – coefficient or characteristics
Reexamination Certificate
1999-11-15
2001-05-22
Noori, Max (Department: 2855)
Measuring and testing
Frictional resistance, coefficient or characteristics
Reexamination Certificate
active
06234003
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of judging the lip turnover of a seal having a lip, such as an oil seal or G seal with a lip, in inserting the seal onto a shaft, and an apparatus for inserting such a seal.
2. Description of the Related Art
In seals with a lip, the point portion of the lip consisting of an elastic member, such as rubber, makes close contact with a shaft to form a seal portion and prevents leakage of oil and invasion of foreign matter, such as dust, with the seal portion. When such a seal with a lip is fitted on a shaft, the direction of the lip must be directed in a direction in which the seal is inserted onto the shaft.
However, there are cases where at the time of insertion the lip of the seal is turned over due to friction between it and the shaft and is directed in a direction opposite the insertion direction. If the lip is turned over in this way, a gap will be developed between the seal portion and the shaft and a situation such as leakage of oil and invasion of dust will take place.
For example, in Japan Utility Model No. 3007446 (Japan Utility Model Application No. HEI 6-10536), it has been proposed to provide a cutout in the outer circumferential edge to easily detect by an air leakage test whether or not the lip has been turned over.
The air leakage test, however, requires an air supply unit, piping for passing air from the air supply unit to a chuck hand for clamping a seal, and an expensive sensor for detecting air leakage. Furthermore, an exclusive chuck hand for leakage detection is required. Thus, providing large-scale equipment solely for the purpose of detecting the turnover of a seal is not only disadvantageous in costs, but it also takes time to detect air leakage. Furthermore, the production efficiency is reduced.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a turnover judgment method and a seal insertion apparatus which are capable of judging with simple equipment whether or not the lip of a seal has been turned over in inserting the seal onto a shaft.
To achieve this end, the invention as set forth in a first aspect is constituted by a turnover judgment method comprising the steps of: inserting a seal with a lip onto a shaft; detecting insertion force of the seal; and judging turnover of the lip, based on a result of the detection.
According to the invention as set forth in the first aspect, the turnover of the lip is judged based on the insertion force of the seal. Therefore, the turnover of the lip can be judged without providing large-scale equipment. Also, when the lip is turned over, the turnover can be immediately detected and a measure to counter the turnover can be quickly taken. As a consequence, the time for inserting the seal onto the shaft can be shortened.
The invention as set forth in a second aspect is constituted by a turnover judgment method comprising the steps of: (a) performing once or a plurality of times at a time a first operation in which a seal with a lip is inserted once onto a shaft at a first predetermined position, a second operation in which the seal is pulled out from the first predetermined position to a second predetermined position at which the seal does not slip out of the shaft, and a third operation in which the seal is again inserted on the shaft from the second predetermined position; (b) detecting insertion force applied during the first operation; and (c) judging turnover of the lip, based on a result of the detection.
According to the invention as set forth in the second aspect, the turnover of the lip is judged based on the insertion force applied during the first operation. Therefore, when the lip is turned over, the turnover can be immediately detected.
In the invention as set forth in a third aspect, when the seal is inserted on the shaft in the same procedure as the aforementioned, the pull-out force applied during the second operation is detected and the turnover of the lip is judged based on a result of the detection.
According to the invention as set forth in the third aspect, the turnover of the lip is judged based on the insertion force applied during the second operation. Therefore, with the state in which the seal is adapted to the shaft as compared with the first operation, the pull-out force is detected and the turnover of the lip can be judged with a high degree of accuracy.
In the invention as set forth in a fourth aspect, when the seal is inserted on the shaft in the same procedure as the aforementioned, the insertion force applied during the second operation is detected and the turnover of the lip is judged based on a result of the detection.
According to the invention as set forth in the fourth aspect, the turnover of the lip is judged based on the insertion force applied during the third operation. Therefore, with the state in which the seal is further adapted to the shaft as compared with the second operation, the insertion force is detected and the turnover of the lip can be judged with an even higher degree of accuracy.
In the invention as set forth in a sixth aspect, when the seal is inserted on the shaft in the same procedure as the aforementioned, the insertion force applied during the first operation is detected and the pull-out force applied during the second operation is detected. The ratio between the detected insertion force and the detected pull-out force is computed, and the turnover of the lip is judged based on the value of the computed ratio.
According to the invention as set forth in the sixth aspect, the turnover of the lip is judged based on the ratio between the insertion force during the first operation and the pull-out force during the second operation. Therefore, even when external noise gets into the detected value of the insertion force or pull-out force, the noise component is easily canceled and the turnover of the lip can be judged with a high degree of accuracy.
In the invention as set forth in a seventh aspect, when the seal is inserted on the shaft in the same procedure as the aforementioned, the insertion force applied during the first operation is detected and the insertion force applied during the third operation is detected. The ratio between the detected two insertion forces is computed, and the turnover of the lip is judged based on the value of the computed ratio.
According to the invention as set forth in the seventh aspect, the turnover of the lip is judged based on the ratio between the insertion force during the first operation and the insertion force during the third operation. Therefore, even when external noise gets into the detected values of the two insertion forces, the noise component is easily canceled and the turnover of the lip can be judged with a high degree of accuracy.
In the invention as set forth in a ninth aspect, when the seal is inserted on the shaft in the same procedure as the aforementioned, the pull-out force applied during the second operation is detected after a fixed time has elapsed since a start of the second operation, and the turnover of the lip is judged based on a result of the detection.
According to the invention as set forth in the ninth aspect, the pull-out force applied during the second operation is detected after a fixed time has elapsed since a start of the second operation. Therefore, the pull-out force is detected after the pull-out operation has been stabilized. Even when external noise gets into the detected value of the pull-out force, the noise component is easily canceled and the turnover of the lip can be judged with a high degree of accuracy.
In the invention as set forth in a tenth aspect, when the seal is inserted on the shaft in the same procedure as the aforementioned, the insertion force applied during the third operation is detected after a fixed time has elapsed since a start of the third operation, and the turnover of the lip is judged based on a result of the detection.
According to the invention as set forth in the tenth aspect, the insertion force applied during the third operation i
Hiramatsu Motoi
Kobayashi Kenji
Nakajima Mitsuru
Noori Max
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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