Patent Description:
It is a conventional practice to form protrusions that are called flare, bulge, or spool on end parts of steel or synthetic resin pipes used in various types of tubing such as automotive tubing, for connection with rubber hoses or the like, or with a connection component called "quick connector", in a process of setting up a tubing system. When applied to connection with a rubber hose or the like, the protrusion can ensure and maintain an airtight seal in the connected parts, as well as serves to prevent unwanted disconnection of the hose or the like from the pipe by increasing the friction resistance.

Hydroforming has been known before as a method of forming protrusions on pipes. In this forming method, the pipe set in the mold is filled with a pressurized liquid while being compressed from both ends by pistons advanced from left and right so as to transform the pipe to conform to the recess formed in the mold (see, for example, PTL <NUM>).

<CIT> relates to an expansion tool for expanding tube ends, and forms the basis for the preamble of claim <NUM>. Said expansion tool has an expansion mandrel and a counter-support, said expansion mandrel consisting of a tow-bar and an elastic rubber expansion element surrounding it. The counter-support supports the expansion element on the base extremity and radially surrounds it at a distance. The tow-bar is anchored in a bolt fastening element and the counter-support can be impinged upon via a pressure bar element that projects beyond the bolt fastening element in the longitudinal direction of the tow-bar.

<CIT> describes a method for shaping a normally rigid plastic pipe. A normally rigid plastic pipe is shaped by softening a selected zone of the pipe, inserting into the softened zone a resiliently deformable mandrel and pressing axially on opposite sides of the mandrel. This expands the mandrel radially into frictional engagement with the softened pipe zone. Contemporaneously the mandrel is shortened axially, thereby correspondingly expanding radially and shortening axially the softened portion of the pipe while proportionately thickening its side walls.

<CIT> describes a method and apparatus for producing a header with openings. An opening is formed while pressure is applied against the header to prevent deformation of the header. The internal pressure can be between <NUM> MPa and <NUM> MPa, more preferably between <NUM> MPa and <NUM> MPa.

<CIT> describes a method and apparatus for forming a flared end on a pipe, in which a male die is positionable over the pipe at a location adjacent to but spaced from the end of the pipe. An elastomeric bung is mounted on the end of the piston rod of a fluid pressure operated piston and cylinder arrangement, the rod extending through a female die. The end of the bung is fitted over the rod and the bung and the end of the pipe abut the inner surface of the female die.

<CIT> describes a process and a device for processing a plastically deformable workpiece. Such a processing device comprises a mold in or on which the workpiece can be placed, an elastically deformable material that can be applied to a side of the workpiece facing away from the mold, and pressure means for exerting a compressive force in a first direction on the elastically deformable material, so that the elastically deformable material expands in a second direction and presses the workpiece against the mold.

<CIT> relates to a method for expanding of the connection end portion of a synthetic resin pipe, wherein after the connection end part of a pipe is formed into an expanded condition by heating, the expanded pipe condition is fixed by forcibly cooling while the pipe is under the expanded pipe condition. Then, the connection end part 7a of the expanded pipe condition is inserted over a joint and it is shrunk to the original diameter by heating again to connect the joint.

<CIT> relates to a method of forming a locking step for connecting a pipe body at an end of a thermoplastic pipe such as a vinyl chloride pipe. A locking step for locking a joint has a sharp engagement as close to a right angle as possible. Even if the bending angle part is made of a material structure and even if a folding angle locking step part is formed, a fragile structure part cannot support the fluid pressure in the pipe. Thus, a simple processing tool is provided and a special deformation action at the time of tensioning of an elastic flexible material is utilized.

<CIT> describes a crosslinked crystalline thermoplastic resin molding which not only withstands short-term heating at a temperature not lower than the melting point, such heat resistance being necessary for soldering resistance, but has satisfactory creep resistance at high temperatures around the melting point and retains the impact resistance and toughness inherent in the crystalline thermoplastic resin molding.

The problem with the conventional hydroforming method for forming protrusions described above was that it required a sturdy sealing structure for hermetically containing the highpressure oil, and since the pipe was axially compressed by applying forces from both ends, the equipment tended to have a complex and bulky structure and the facility cost was high. Another problem was that it was hard to form a protrusion close to an end of the pipe, or to form a protrusion on a pipe that has already been bent, because of the need to clamp both ends of the pipe.

The present invention was made in view of the problems encountered by the background art described above. An object of the present invention is to provide a pipe end processing device that allows a protrusion to be formed on a pipe by applying a force only from one end, thus allowing a facility cost reduction through size reduction and simplification of the processing device, enables formation of a protrusion close to an end of a pipe or on a pipe that has already been bent, and serves also as a device for clamping an end part of a pipe.

To achieve the object noted above, the present invention provides a pipe end processing device as set forth in the following:.

The pipe end processing device according to the present invention described above allows a protrusion to be formed on a pipe by applying a force only from one end, thus allowing a facility cost reduction through size reduction and simplification of the processing device, enables formation of a protrusion close to an end of a pipe or on a pipe that has already been bent, and serves also as a device for clamping an end part of a pipe.

Hereinafter, an embodiment of the pipe end processing device according to the present invention will be described in detail with reference to the drawings.

The drawings illustrate one embodiment of the pipe end processing device according to the present invention, wherein the illustrated pipe end processing device <NUM> includes a chuck <NUM>, a female die <NUM>, and a male die <NUM>.

The chuck <NUM> is made up of a pair of combined chuck splits 10A and 10B so that it can be split into upper half and lower half. The chuck splits 10A and 10B are respectively formed with grooves 11A and 11B for holding a pipe P and female die receiving grooves 12A and 12B in which the female die <NUM> fits. The chuck splits 10A and 10B that form the chuck <NUM> are configured to move up and down respectively by a drive device (not shown) to clamp or release an end part of a pipe P.

The female die <NUM> is formed in a columnar shape, with a through hole <NUM> in the axial center. The through hole <NUM> has a radially increasing inner circumferential surface on one side where there is a molding surface <NUM> that imparts a form to a pipe P. In the illustrated embodiment, this molding surface <NUM> is a cavity <NUM> formed by an annular recess for forming an annular protrusion A called bulge to an end part of the pipe P. The female die <NUM> also has a position restricting groove <NUM> on an outer circumferential surface. The female die <NUM> should preferably be made of a material that has rigidity and good heat conductivity, for example a metal having heat-resistant and pressure-resistant characteristics such as aluminum, copper, SUS, brass, etc..

The male die <NUM> is made up of a metal core <NUM> inserted into the through hole <NUM> in the female die <NUM> described above, and a tubular elastic body <NUM> fitted on this metal core <NUM>.

In the illustrated embodiment, external threads <NUM> are formed at the distal end of the metal core <NUM>, and with a nut <NUM> that doubles as a pressing plate for pressing the tubular elastic body <NUM> screwed on the external threads <NUM>, the tubular elastic body <NUM> fitted on the metal core <NUM> is supported thereon.

The metal core <NUM> is configured to move along the axial direction by a drive device (not shown) provided on the other side of the female die <NUM> (left side in the drawing). The tubular elastic body <NUM> fitted on the metal core <NUM> is axially compressed by the movement of the metal core <NUM> to radially expand by deformation, thereby pressing a surface to be processed of the pipe P against the molding surface <NUM> of the female die <NUM> and causing a plastic deformation of the pipe P. The metal core <NUM> is formed into tubular shape so that it allows a fluid to pass through therein, and configured to allow a high-temperature fluid Z to be introduced into the attached pipe P via the tubular metal core <NUM>.

The tubular elastic body <NUM> is formed as a tubular member having an outside diameter that is equal to or slightly smaller than the inside diameter of the pipe P to be processed, and an inside diameter that is equal to or slightly larger than the outside diameter of the metal core <NUM>. The tubular elastic body <NUM> should preferably be formed of silicone rubber, ethylene rubber, butyl rubber, or chloroprene rubber, from the viewpoints of elasticity, and shock-resistant and heat-resistant characteristics. The tubular elastic body <NUM> need not necessarily be made of a single material and may have a double-layer structure using different materials for inner layer and outer layer.

The pipe end processing device <NUM> according to the present invention configured as described above is operated as follows wherein it processes an end part of the pipe P as well as clamps the end part.

First, as shown in <FIG>, the chuck splits 10A and 10B that form the chuck <NUM> are moved up and down respectively by the drive device (not shown) to open the chuck <NUM> so that there is formed a space for inserting a pipe P. Then, the pipe P is moved by a robot hand or the like (not shown), and as shown in <FIG>, an end part of the pipe P is attached to the tubular elastic body <NUM> of the male die <NUM> and inserted into the cavity <NUM> inside the molding surface <NUM> of the female die <NUM>.

Next, as shown in <FIG>, the chuck <NUM> is closed by the drive device (not shown) to clamp the end part of the pipe P with the chuck splits 10A and 10B. In this state, as shown in <FIG>, the metal core <NUM> is pulled outward (leftward in the drawing) by the drive device (not shown) to axially compress the tubular elastic body <NUM> fitted on the metal core <NUM> so that the elastic body deforms to radially expand and presses the surface to be processed of the pipe P against the molding surface <NUM> of the female die <NUM>, whereby an annular protrusion A called bulge is formed by the molding surface <NUM> on the end part of the pipe P. At this time, as shown in <FIG> to a larger scale, a high-temperature fluid (e.g., heated steam at a temperature of <NUM> to <NUM> and a pressure of <NUM> to <NUM> MPa) Z can be introduced into the pipe P via the tubular metal core <NUM>. This causes thermal expansion of the tubular elastic body <NUM> so that the pressing force is increased, enabling more precise processing of the pipe P and enhancing the clamping force. Also, the heating of the entire pipe P allows certain processing such as bending to be performed to the pipe P.

When the intended processing operation to the pipe P is finished, the grip by the pipe end processing device <NUM> according to the present invention is loosened and the pipe P is pulled out. To release the pipe P from the hold, first, the pulling of the metal core <NUM> by the drive device (not shown) is stopped so that the tubular elastic body <NUM> that has deformed and expanded returns to its original state by its elasticity, as shown in <FIG>. The supply of a high-temperature fluid Z, if any, into the pipe P through the metal core <NUM> is stopped. Next, the chuck <NUM> is opened by the drive device (not shown) to release the pipe P from the grip by the chuck splits 10A and 10B as shown in <FIG>. Next, the pipe P is pulled out of the pipe end processing device <NUM> by the robot hand or the like (not shown) as shown in <FIG>.

The annular protrusion A called bulge formed to the end part of the pipe P as described above is formed by the molding surface <NUM> of the female die <NUM> that has a uniform surface without joints, so that a very smooth annular protrusion A without irregularities such as burrs can be formed, and the protrusion A, which does not require any secondary processing such as polishing, when applied to connection with a rubber hose or the like, can ensure and maintain an airtight seal in the connected parts, as well as serves to prevent unwanted disconnection of the hose or the like from the pipe P by increasing the friction resistance. The pipe end processing device <NUM> according to the present invention described above allows the protrusion A to be formed on the pipe P by applying a force only from one end, i.e., allows a facility cost reduction through size reduction and simplification of the processing device. Moreover, it enables formation of a protrusion A close to an end of a pipe P or on a pipe P that has already been bent, and since it serves also as a device for clamping an end part of a pipe P, the device can be used also as a chuck device when bending or otherwise processing the pipe P.

Claim 1:
A pipe end processing device comprising:
a female die (<NUM>) having a molding surface (<NUM>) for forming a protrusion; and
a male die (<NUM>) that presses a surface to be processed of a pipe (P) against the molding surface (<NUM>) of the female die (<NUM>),
the female die (<NUM>) having a through hole (<NUM>) with one side thereof being radially increased, the through hole (<NUM>) having the molding surface (<NUM>) for forming the protrusion formed on an inner circumference on the one side of the through hole (<NUM>), and
the male die (<NUM>) including
a metal core (<NUM>) passed through the through hole (<NUM>) of the female die (<NUM>) and configured to be axially moved by a drive device provided on another side of the female die (<NUM>), and
a tubular elastic body (<NUM>) fitted on one end part of the metal core (<NUM>), the one end part protruding from the one side of the female die (<NUM>), the tubular elastic body (<NUM>) being configured to be axially compressed by a movement of the metal core (<NUM>) to radially expand by deformation thereby to press the surface to be processed of the pipe (P) against the molding surface (<NUM>) of the female die (<NUM>),
characterized in that
the pipe end processing device further comprises a chuck (<NUM>) that clamps an end part of the pipe (P) in addition to the female die (<NUM>) and the male die (<NUM>), wherein the metal core (<NUM>) is formed into tubular shape, the pipe end processing device being configured to introduce a high-temperature fluid (Z) which is a heated steam at a temperature of <NUM> to <NUM> and a pressure of <NUM> to <NUM> MPa into the pipe (P) via the tubular metal core (<NUM>).