JP6543045B2 - Stainless steel pipe for press fitting - Google Patents

Description

  The present invention relates to a stainless steel pipe, and more particularly to a stainless steel pipe for connection by a press-type pipe joint.

In recent years, the method of producing a pipe joint body by plastically processing a stainless steel pipe and connecting the stainless steel pipe using a press-type pipe joint in which an O-ring is disposed at the steel pipe connecting end of the pipe joint body is widely used. It is The connection work is basically performed in the following procedure.
(1) Pipe cutting work: Cut a stainless steel pipe at right angles to the pipe axis using a rotary cutter or an electric pipe cutter.
(2) Deburring work: Use a file or reamer to remove burrs and burrs on the cut end of the stainless steel pipe and chamfer the cut end.
(3) Marking work: Insert a stainless steel pipe into a dedicated jig and mark a line mark indicating the insertion allowance on the surface of the stainless steel pipe.
(4) Insertion work: Insert a stainless steel pipe up to the line mark into the press fitting.
(5) Setting work: Position the curling part holding the O-ring of the press-type pipe joint in the recess of the upper and lower dies of the special tightening tool, and set the special tightening tool to the press-type pipe joint.
(6) Press work: Activate the dedicated tightening tool to bring the upper and lower dies close to each other, and press until the press-type pipe joint and the stainless steel pipe inside it make predetermined deformation.
(7) Checking operation: Remove the dedicated tightening tool and use a dedicated gauge to check if the specified tightening has been performed.

  Currently, all work in this connection work is performed on site. Therefore, the cut end of the stainless steel pipe is cut diagonally or stepped, and the insertion margin to the pipe joint becomes uneven, which tends to cause leakage, and an excessive force is applied during the cutting operation to deform the stainless steel pipe into a flat shape. By doing this, the risk of causing leakage was increased. Furthermore, the on-site deburring and chamfering operations tend to be rather rough, and if the deburring and chamfering are insufficient, the O-rings are easily damaged when inserted into the pipe joint and cause leakage. In addition, if the marking operation is performed incorrectly, there is a problem that the insertion allowance into the pipe joint is insufficient and the pipe joint is inadvertently dropped.

  In addition, since there is no means for checking during the press work whether the stainless steel pipe is inserted into the pipe joint up to a predetermined insertion margin in the press work which ultimately determines the work result, Even if the positional deviation occurs during the operation, it can not be recognized, and the pressing operation has been performed with the positional deviation.

Electronic catalog issued by Bencan Co., Ltd. "Stainless steel pipe corresponding pipe joint for general piping-Press-type pipe joint" (http://www.benkan.com/prosumer/mj/catalogue/catalogue/pdf/Molco_Catalogue.pdf)

  According to the present invention, operations which require on-site operations, ie operations excluding insertion operations, setting operations, press operations and confirmation operations, ie, pipe cutting operations, deburring operations and marking operations, are performed in the factory. An object of the present invention is to provide a stainless steel pipe for press-type pipe joint which can reduce the possibility of human error in the on-site operation.

  The stainless steel pipe for press-type pipe joint according to the present invention is cut to a required length in a processing plant, and then finish processing such as deburring and chamfering is applied to the cut end surface. On the outer surface of this stainless steel pipe, a line mark is drawn at a position separated from the cut end face of the stainless steel pipe by an interval corresponding to the insertion allowance selected according to the applicable pipe joint, and the pressure discoloration seal is a line The mark is disposed circumferentially continuously at a position axially inward of the mark with respect to the mark or at a predetermined interval.

  The line mark is drawn using water that is commonly used in construction sites etc. and strong adhesion ink that can not be erased by thinner or the like, and the pressure discoloration seal is used for upper and lower dies used during press work. It is preferable to have a length in the axial direction substantially the same as the width of the pressing portion located on one side of the recess.

  The stainless steel pipe for press-type pipe joint of the present invention formed as described above inserts the stainless steel pipe up to the line mark into the press-type pipe joint (insertion operation) in the same manner as in the prior art. Position the curling part holding the ring in the recess of the upper and lower dies of the special tightening tool, set the special tightening tool on the press-type pipe joint (setting operation), operate the special tightening tool and set the upper and lower dies They are brought into close proximity to each other, pressed until the press fitting and the stainless steel pipe inside thereof make a predetermined deformation (pressing work), and a dedicated tightening tool is removed, and a specific tightening is performed using a dedicated gauge. Make sure (confirmation work). At this time, since all preliminary processing such as pipe cutting, deburring and marking is previously performed in the factory, it is possible to eliminate the possibility of imprecise and / or incomplete processing on the site. Therefore, not only can the working time be reduced simply at the site, but also the required task can be performed accurately at the site of the inserting operation, the setting operation and the pressing operation.

  In addition, since the line mark is drawn with strong adhesion ink, it is possible to prevent the line mark from being lost from manufacturing to work, so the stainless steel pipe is securely inserted into the pipe joint to a predetermined insertion margin It can be done. Also, by providing the pressurized color changing seal to be positioned within the pressure range of the pressing portion of the die, the pressurized color changing seal may protrude from the die even if the stainless steel pipe comes out of the pipe joint at the time of pressing operation. Thus, the relative positional deviation between the stainless steel pipe and the pipe joint can be recognized by the operator, and incomplete pressing work can be prevented.

FIG. 1 is a half sectional view showing a stainless steel pipe and a press-type pipe joint according to an embodiment of the present invention. FIG. 2 is a half sectional view showing the insertion positional relationship between the stainless steel pipe and the pipe joint shown in FIG. FIG. 3 is a half sectional view showing a stainless steel pipe inserted into a pipe joint. FIG. 4 is a half sectional view showing a state in which a pipe joint into which a stainless steel pipe is inserted is deformed under pressure. FIG. 5 is a half sectional view showing a connected state of a completed stainless steel pipe and a pipe joint. FIG. 6 is a half sectional view showing a stainless steel pipe and a pipe joint connected in an incomplete manner.

  As shown in FIG. 1, a stainless steel pipe 1 for piping according to an embodiment of the present invention is connected to a conventional press-type pipe joint 2 by a dedicated clamping tool (only the die 3 is shown). In the case of the drawing, the pipe joint 2 is shown in the form of a socket-type pipe joint so as to compare the crimped state and the non-crimped state, but the single socket type, elbow type, tee type, union type It will be readily understood that the invention can be applied to various press-type pipe joints.

  After the stainless steel pipe 1 is cut into a required length in a processing plant, the cut end face 10 is subjected to finish processing such as deburring and chamfering. The processing from cutting to finishing may be sequentially performed using a processing device (for example, a pipe cutter, reamer, etc.) corresponding to each work, but, for example, manufactured and sold by Ridge Tool, Inc., Ohio, USA Preferably, it is processed collectively by a processing machine such as RIDGID Model 122 high speed pipe end processing machine.

  At the outer surface of the stainless steel pipe 1 subjected to finish processing of the cut end surface, a position spaced apart inward in the axial direction from the cut end surface 10 by the insertion margin L of the stainless steel pipe 1 determined according to the pipe joint 2 used. Line marks 11 are drawn circumferentially by a paint device (not shown). A pressurized color-change seal 12 that changes color when pressure is applied is provided inward of the line mark 11 in the tube axial direction. The pressure discoloration seal 12 is disposed so that the die 3 of the dedicated tightening tool is positioned in the region of the pressure portion 31 in contact with the stainless steel pipe 1 at the time of press work described later. It is preferable that the position in the tube axial direction inner end of the pressure discoloration seal 12 be substantially the same as the position in the tube axial direction inner end of the pressure portion 31. In addition, the pressurized color-changing seal 12 is provided continuously or at a predetermined distance from each other in the circumferential direction of the stainless steel pipe 1 (in the illustrated case, the case of mutual separation is shown). It is desirable that the line mark be drawn using a strong adhesion ink so as not to be erased by water, thinner, etc., which are generally present at construction sites and the like.

  The stainless steel pipe 1 of the present invention formed as described above continues the pipe joint 2 until the line mark 11 coincides with the end of the pipe joint 2 on the cut end face 10 side provided with the line mark 11 and the pressurized color change seal 12. By inserting in, the required insertion margin L is obtained (see FIGS. 2 and 3). Next, with the curled portion 21 holding the O-ring 20 of the pipe joint 2 fitted in the recesses 30, 30 of the upper and lower dies 3, 3 of the dedicated fastening tool, the dedicated fastening tool is operated The dies 3 and 3 are brought close to each other, and pressed until the pipe joint 2 located between the dies 3 and 3 and the portion of the stainless steel pipe 1 inside thereof are subjected to predetermined deformation (see FIG. 4). At this time, the dedicated tightening tool locally deforms the pipe joint 2 and the stainless steel pipe 1 inside the pipe joint 2 by pressing the outer surface of the pipe joint 2 by the part on the pipe joint 2 side of the recess 30 of the die 3 Then, the pressing is stopped in response to the rapid increase in the compression resistance caused by the portion on the stainless steel pipe 1 side pressing the recess 30 of the die 3 against the outer surface of the stainless steel pipe 1. Therefore, the pressurized color-changing seal 12 of the stainless steel pipe 1 located in the area of the pressurizing unit 31 is discolored by the final pressing of the die 3 onto the outer surface of the stainless steel pipe 1 (see FIG. 5).

  During the pressing operation, the line mark 11 is hidden by the die 3. Therefore, even if the stainless steel pipe 1 comes out of the pipe joint 2 during the operation and the required insertion margin L can not be secured, the worker may proceed with the operation without recognizing it. However, in the case of the present invention, since the position in the tube axial direction inner end of the pressure discoloration seal 12 is substantially the same as the position in the tube axial direction inner end of the pressure portion 31, the pressure from the die 3 is added. After pressing, it is a matter of course whether or not the press work secures the required insertion allowance L by confirming the presence / absence of the pressure-sensitive color seal 12 and the degree of the exposure (see FIG. 6; pressure discoloration) The seal 12 remains undiscolored)), which can also be determined during the pressing operation (compare FIGS. 5 and 6). After the pressing operation is completed, it is desirable to remove the dedicated tightening tool and to check whether the predetermined tightening has been performed using a dedicated gauge as in the conventional case.

DESCRIPTION OF SYMBOLS 1 stainless steel pipe 10 cut end face 11 line mark 12 pressure discoloration seal 2 pipe joint 20 O-ring 21 curled portion 3 die 30 recessed portion 31 pressurized portion L insertion margin

Claims (2)

After cutting a stainless steel pipe to a required length in a processing plant, the cut end face is subjected to finish processing such as deburring and chamfering, and the outer surface has an interval corresponding to the insertion allowance selected according to the applicable pipe joint. A line mark is drawn at a position separated from the cut end face, and a pressurized color change seal is disposed at a position axially inward of the line mark in the axial direction with a continuous or predetermined interval in the circumferential direction ,
The pressurized color-changing seal has a length in the axial direction substantially the same as the width of each pressing portion located on both sides of the recess of the die used in the pressing operation . Stainless steel for press-type pipe joint Steel pipe.   The stainless steel pipe for a press-type pipe joint according to claim 1, wherein the line mark is drawn using a strong adhesion ink so as not to be erased by water, a thinner, etc., which is generally present at a construction site or the like.

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