Pipe joints or couplings – With means blocking release of holding means – Thread lock
Reexamination Certificate
1999-03-15
2002-01-01
Luu, Teri Pham (Department: 3627)
Pipe joints or couplings
With means blocking release of holding means
Thread lock
C285S093000, C285S331000, C285S334500, C285S342000, C285S906000
Reexamination Certificate
active
06334632
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a synthetic resin-made fastening-limiting device employed for limiting a fastening force of a joint fastening member in case of fastening a connection portion for connecting a pipe to a pipe receiving port on the side of a joint by means of the fastening member. The screw amount of the fastening member is appropriately adjusted, whereby the fastening-limiting device ensures the sealing property of the connection portion between the pipe receiving port and the pipe and prevents the pipe from slipping out of the pipe receiving port.
2. Description of the Prior Art
A pipe for transporting a fluid, which is used in a semiconductor production process, is often required to have the particularity of the use environment such as chemical resistance and corrosion resistance. In consideration of the particularity of the use environment, a synthetic resin-made pipe which has certain properties is used as pipes of this kind. Similarly, as the material of joints which are interposed in many connecting and branching portions of such a pipe (including joints which are integrally attached to valves and the like connected to the pipe), used is synthetic resin having certain properties.
Such a connection structure is often employed in which, by the fastening force exerted by a fastening member screwed to a pipe receiving port on the side of the joint, the pipe inserted into the pipe receiving port is prevented from accidentally slipping off and the sealing property of the connection portion is ensured. In the connection structure, the function of preventing accidental slipping-off of the pipe due to the fastening of the fastening member, and the performance of ensuring the sealing property of the pipe connection portion are exerted only after the contact pressure against the connection portion, which is generated by the fastening of the fastening member, reaches a reference contact pressure.
When such a connection structure is employed, conventionally, means for defining the degree of the fastening force of the fastening member to an appropriate level in order to prevent the pipe from slipping off and ensure the sealing property is realized by a method such as that in which the fastening member is screwed by using a torque wrench, or that in which, when the fastening member is to be screwed to the pipe receiving port, the fastening member is caused to make a predetermined number of rotations.
However, such methods including the method in which a torque wrench is used, and that in which the fastening member makes a predetermined number of rotations have a problem in that these methods are cumbersome and require skill.
When existence
onexistence of a forge of fastening of the fastening member, or adequateness of the fastening state of the fastening member is to be determined, cumbersome checking work must be conducted using tools and jigs. Therefore, it is difficult to completely eliminate an accident due to a forge of fastening or a failure of fastening.
SUMMARY OF THE INVENTION
The present invention has been developed; and in view of the above mentioned circumstances and problems.
It is an object of the present invention to enable an appropriate screw amount of a fastening member to be determined without using a prior art method that is cumbersome and requires skill.
It is another object of the present invention that an appropriate screw amount of a fastening member at which the above-mentioned reference contact pressure is obtained can be determined without using a prior art method that is cumbersome and requires skill.
It is still another object of the present invention that a forge of fastening of a fastening member, or adequateness of the fastening state of the fastening member can be checked easily and rapidly.
It is a still further object of the present invention that a fastening member is prevented from being fastened at a degree exceeding an allowable fastening limit.
A synthetic resin-made fastening-limiting device for a joint fastening member, employed with a fastening member for fastening a pipe which is inserted into a pipe receiving port on the side of a joint, comprises:
a ring portion which is fittable onto an outside of the pipe receiving port;
a first abutting portion disposed on one end face in an axial direction of the ring portion, for abutting against a reference face disposed on the side of the joint;
a protrusion which protrudes from another end face in the axial direction of the ring portion; and
a second abutting portion which is formed by a tip end of the protrusion, for abutting against a confronting portion when the fastening member having said confronting portion confronting the reference face is screwed to the pipe receiving port.
In the fastening-limiting device of the present invention, when the fastening member is screwed to the pipe receiving port onto which the ring portion is fitted, the protruding confronting portion of the fastening member pushes the fastening-limiting device to cause the first abutting portion to abut against the reference face on the side of the joint. Under this state, in the fastening-limiting device, the first abutting portion abuts against the reference face on the side of the joint, and the second abutting portion abuts against the confronting portion on the side of the fastening member.
In case that the fastening member is further screwed from this condition, a force required for screwing is increased, which is recognized by the operator. Then, the screw amount of the fastening member can be determined without using the prior art method that is cumbersome and requires skill.
Preferably, a distance in the axial direction of the ring portion between the first and second abutting portions is equal to a gap between the reference face and the confronting portion at the timing when a screw amount of the fastening member to the pipe receiving port reaches an appropriate value.
In the fastening-limiting device having this configuration, when the first abutting portion abuts against the reference face on the side of the joint, and the second abutting portion abuts against the confronting portion on the side of the fastening member, a gap between the reference face and the confronting portion of the fastening member is equal to a distance between the first abutting portion and the second abutting portion, whereby the screw amount of the fastening member reaches an appropriate amount.
Preferably, a distance between the first abutting portion and the other end face in the axial direction of the ring portion is equal to the gap between the reference face and the confronting portion at the time when the screw amount of the fastening member to the pipe receiving port reaches a limit of screwing, and the ring portion is provided with a recessed portion allowing the protrusion pressed by the confronting portion to fall down.
In this configuration, the first abutting portion abuts against the reference face on a side of the joint, and the second abutting portion abuts against the confronting portion of the fastening member. Thereafter, the fastening member is further a screwed to make the protrusion fall down into the recessed portion. As a result, the first abutting portion abuts against the reference face on a side of the joint, and the other end face in the axial direction of the ring portion abuts against the confronting portion on a side of the fastening member. In this time, the gap between the reference face and the confronting portion of the fastening member is equal to the distance between the first abutting portion and the other end face in the axial direction of the ring portion, whereby the screw amount of the fastening member reaches the limit so as to make it impossible to screw the fastening member.
The screwing position of the fastening member at the time when the screw amount of the fastening member reaches the appropriate value is indicated as “the initial appropriate position”, and the screwing position of the fastening member at the time when t
Fujii Makoto
Ishida Takuya
Nishio Kiyoshi
Okamoto Yutaka
Jones Tullar & Cooper P.C.
Luu Teri Pham
Nippon Pillar Packing Co. Ltd.
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