JP5854457B2 - Metal pipe bending apparatus and water-soluble lubricant supplying method - Google Patents

Description

  The present invention relates to a metal pipe bending apparatus for bending a metal pipe with a desired curvature, and more specifically, a metal pipe bending apparatus provided with a water-soluble lubricant supplying means for supplying an appropriate amount of water-soluble lubricant into the metal pipe, and a water-soluble The present invention relates to a method for pressurizing a functional lubricant.

  In the metal tube bending apparatus, a bending mandrel is inserted into a bending portion of the metal tube to be bent to prevent deformation of the metal tube during bending. In that case, in order to prevent the friction force of the processing mandrel in the metal tube from becoming high, scratches are formed on the inner peripheral surface of the metal tube, or the metal tube vibrates and the bending accuracy is deteriorated. As shown in FIG. 1, a nozzle connected to a lubricating oil supply flow path for discharging lubricating oil is provided on the mandrel, and the pump is driven during bending to supply the lubricating oil between the mandrel and the inner peripheral surface of the metal tube. Yes.

  The lubricating oil supplied to the mandrel at the time of bending described above is difficult to break the oil film formed between the mandrel and the inner peripheral surface of the metal tube. Can be suppressed. However, when welding to a metal pipe after bending, the lubricating oil adhering to the metal pipe may cause poor welding, or toxic smoke may be generated due to the heat of welding and contaminate the work environment. Prior to the welding line, a cleaning operation is required to remove the lubricating oil adhering to the inner surface of the metal tube.

  The above-described problems can be eliminated by using a water-soluble lubricant as a lubricant supplied between the mandrel and the inner peripheral surface of the metal tube during bending. However, since the water-soluble lubricant itself is more susceptible to film breakage than the lubricating oil, a large amount of water-soluble lubricant is required during bending to prevent the formation of wrinkles and vibration during bending. Has to be supplied, and the amount of water-soluble lubricant consumed increases, resulting in an increase in bending costs.

  Moreover, in order to supply a large amount of water-soluble lubricant between the mandrel and the inner peripheral surface of the metal tube during bending, it is necessary to pressurize and inject the water-soluble lubricant at a high pressure. An electric pump is used as the pressurizing means to pressurize the water-soluble lubricant to a desired pressure. To pressurize to a desired high pressure, a high-output electric pump must be used, and the device itself However, there is a problem that the size and weight of the device increases and the cost increases.

JP-A-7-39942

  The problem to be solved is that the water-soluble lubricant is more likely to break the film than the lubricating oil, so a large amount of water-soluble lubricant is required to prevent the formation of wrinkles and vibration during bending. Lubricant must be supplied, and the bending cost is increased. In addition, in order to supply a large amount of water-soluble lubricant between the mandrel and the inner peripheral surface of the metal pipe during bending, the water-soluble lubricant must be pressurized at a high pressure by a high-power pump, and the device itself is large. The cost and cost increase.

A metal tube bending apparatus according to claim 1 of the present invention is a metal tube bending apparatus that bends a metal tube by inserting a bending mandrel into a bending portion of the metal tube. A cylinder part that reciprocates a rod supported so as to be slidable in the axial direction , and water-soluble lubricant stored in the tank as the rod of the cylinder part reciprocates is sucked into the pressure part by negative pressure. The pressure increasing means for pressurizing after that, the mixing means for increasing the pressure by mixing compressed air with the water-soluble lubricant pressurized by the pressure increasing means, and attached in the hollow portion of the bending mandrel, A cored bar to which a water-soluble lubricant is supplied from the mixing means, a check ball supported so as to be movable in the axial direction within the hollow part of the cored bar, and a hollow part of the cored bar by energizing the check ball An elastic member that can be closed, or The water-soluble lubricant supply means comprises a check ball when the pressure of the water-soluble lubricant supplied from the mixing means is lower than the elastic force of the elastic member. While maintaining the closed state, when the pressure of the water-soluble lubricant supplied from the mixing means is higher than the elastic force of the elastic member, the check ball is moved against the elastic force of the elastic member to open the hollow portion. The most important feature is that the water-soluble lubricant can be injected .
According to a second aspect of the present invention, there is provided a water-soluble lubricant supply method in which a metal pipe bending apparatus is configured to insert a bending mandrel into a bending portion of a metal pipe to bend the metal pipe. When injecting water-soluble lubricant to the bending site, pressurize the water-soluble lubricant sucked in from the tank with negative pressure, and then apply compressed air to the pressurized water-soluble lubricant. If the pressure of the increased water-soluble lubricant supplied in the hollow portion of the cored bar attached in the hollow portion of the bending mandrel is lower than the required pressure, the water When the pressure of the increased water-soluble lubricant in the hollow portion of the metal core is higher than the required pressure, the water-soluble lubricant can be injected into the metal pipe. Is the most important feature .

  The present invention can prevent an increase in bending cost by circulating and using a large amount of water-soluble lubricant supplied at the time of bending a metal tube. In addition, a large amount of water-soluble lubricant can be pressurized and injected at a high pressure without using a high-power pump, and the device itself can be reduced in size and weight and at a lower cost.

It is a perspective view which shows the outline of a metal pipe bending apparatus. It is a schematic perspective view showing an outline of a bending mandrel. FIG. 3 is a central longitudinal sectional view of FIG. 2. It is explanatory drawing which shows a water-soluble lubricant supply means. It is explanatory drawing which shows the injection state of the pressurized water-soluble lubricant by the metal core. It is explanatory drawing which shows the example of a change of a pressure increase means.

When the pressure of the water-soluble lubricant supplied from the mixing means is lower than the elastic force of the elastic member, the water-soluble lubricant supply means keeps the hollow portion closed by the check ball while being supplied from the mixing means. When the pressure of the water-soluble lubricant is higher than the elastic force of the elastic member, the check ball is moved against the elastic force of the elastic member to open the hollow portion and enable the water-soluble lubricant to be injected. This is the best embodiment.

The present invention will be described below with reference to the drawings showing examples.
As shown in FIG. 1, a bending head 5 is provided on the body 3 of the metal tube bending apparatus 1, and the bending head 5 includes a bending die 9 formed according to the bending radius of the long metal tube 7. Yes. A groove 9 a corresponding to the outer diameter of the metal tube 7 is formed on the outer periphery of the bending die 9, the bending die 9 is rotatably supported together with the bending arm 11, and the bending arm 11 is rotated by a bending arm cylinder 13. The

A clamping die 15 is movably supported on the bending arm 11 so as to be opposed to the bending die 9, and the clamping die 15 is driven by a clamping cylinder 17 to clamp the metal tube 7 in cooperation with the bending die 9. Configured. A wiper mold 19 is disposed on the main body 3 close to the bending mold 9, and a pressure mold 21 is supported so as to be movable facing the wiper mold 19. The pressure die 21 is driven by the connected pressure die cylinder 23 so as to contact the outer peripheral surface of the metal tube 7 and is configured to receive a reaction force during bending.

A set of rails 25 extending in the axial direction of the metal tube 7 is provided on the main body 3, and a movable body 27 is movably supported on the rails 25. The movable body 27 is reciprocated on the rail 25 by a numerically controllable electric motor (not shown) such as a servomotor.

The movable body 27 is provided with a gripping member 29 for gripping the other end of the metal tube 7, and the gripping member 29 is a metal gripped by a numerically controllable electric motor (not shown) such as a connected servo motor. Rotate tube 7. On the other hand, a support member 31 is erected on the rear side of the main body 3, and a bending mandrel 33 arranged coaxially with the metal tube 7 is supported on the support member 31. The bending mandrel 33 has a tip portion inserted from the other end of the metal tube 7 extended to a position corresponding to the bending die 9.

As shown in FIG. 2, the bending mandrel 33 has a base end fixed to the support member 31 and has an outer diameter that can be inserted into the metal tube 7 and has a hollow portion that extends in the axial direction. The shaft member 35 is configured by a plug 37 attached to the tip of the shaft member 35 and having an outer diameter that can be inserted into the metal tube 7 and having a hollow portion extending in the axial direction. The plug 37 is positioned at the tip of the shaft member 35 at a position corresponding to the bending die 9, and a plurality of injection holes 37 a that are inclined in the radial direction or a core metal 43 side described later and communicate with the hollow portion are arranged on the tip. Formed at equal intervals around. Further, a plurality of spherical plugs 39 having a slightly smaller diameter than the inner diameter of the metal tube 7 are pivotally supported at the distal end portion of the plug 37 so as to freely swing with respect to the axial direction.

In addition, it is good also as a structure which forms several opening in the front end surface of the plug 37 with which the said spherical plug 39 is supported so that rocking | fluctuation is possible, and injects a water-soluble lubricant to the spherical plug 39 side from these openings.

In the hollow portion of the plug 37, a cored bar 43 for injecting a water-soluble lubricant supplied from a water-soluble lubricant supply means 41, which will be described later, to the plug 37 side is screwed with its axis aligned. As shown in FIG. 3, the cored bar 43 is formed with a hollow portion extending in the axial direction and communicating therewith. The hollow portion has an axially intermediate portion formed with a small diameter with respect to the rear end side and the front end side. A supply hose 45 from a mixing means 59 (described later) constituting a part of the water-soluble lubricant supply means 41 is connected to the rear end side of the core metal 43 in communication with the hollow portion. Further, a check ball 43a constituting a part of the opening / closing means is mounted in the front end side hollow portion of the core metal 43 so as to be movable in the axial direction, and the check ball 43a is formed by a compression spring or the like mounted in the front end side hollow portion. The opening of the small-diameter hollow portion can be closed by the elastic force of the elastic member 43b constituting a part of the opening / closing means.

That is, when the pressure of the water-soluble lubricant supplied from the mixing means 59 is equal to or lower than the elastic force of the elastic member 43b, the check ball 43a is pressed against the opening end of the small-diameter hollow portion by the elastic force of the elastic member 43b and closed. When the pressure of the water-soluble lubricant is equal to or greater than the elastic force of the elastic member 43b, the check ball 43a against the opening end of the small-diameter hollow portion resists the elastic force of the elastic member 43b. It functions as a check valve that releases the pressure contact and enables the injection of water-soluble lubricant. In addition, the code | symbol 43c in a figure is a stop ring which prevents the elastic member 43b with which the front end side hollow part was mounted | worn.

  The metal tube bending apparatus described above is well known and can be implemented as the present invention as long as it is a metal tube bending apparatus having a structure other than the above and provided with a water-soluble lubricant supply means 41 described in detail below. It is.

As shown in FIG. 4, the main body 46 of the water-soluble lubricant supply means 41 is provided with a tank 47, which is divided into a recovery tank 47a, a metal powder recovery tank 47b, and a supply tank 47c. The recovery tank 47a and the metal powder recovery tank 47b are communicated with each other at the lower part of the partition wall 47d. As will be described later, the water-soluble lubricant that is injected and recovered inside the metal pipe 7 is temporarily stored in the recovery tank 47a. After the accumulation, it flows into the metal powder recovery tank 47b. In the metal powder recovery tank 47b, a metal powder adsorption member 49 to which a permanent magnet is attached is mounted so as to be submerged, and the metal powder contained in the water-soluble lubricant that has flowed into the metal powder recovery tank 47b is magnetically adsorbed. And collect.

A partition plate 47e is provided between the metal powder recovery tank 47b and the supply tank 47c, and the water-soluble lubricant that has recovered the metal powder and overflowed the partition plate 47e in the metal powder recovery tank 47b is supplied into the supply tank 47c. Accumulate.

A pressure increasing means 51 is provided in the main body 46, and the pressure increasing means 51 and the supply tank 47c are connected with a supply pipe 53 provided with a check valve 55. The pressure-intensifying means 51 has a hollow portion therein, a pressurizing portion 51a in which the supply pipe 53 is connected to the input port and a discharge pipe 57 is connected to the output port, and the inside of the hollow portion of the pressurizing portion 51a. The rod 51b is inserted and supported so as to be slidable in the axial direction, and a cylinder portion 51c that reciprocates the rod 51b by compressed air supplied from the compressed air switching control means 63 described later. .

When the rod 51b is moved to the non-pressurizing side in the hollow part of the pressurizing part 51a, the pressure increasing means 51 forms a negative pressure in the hollow part and applies a negative pressure to the water-soluble lubricant stored in the supply tank 47c. When the rod 51b is moved to the pressure side after being sucked into the hollow portion, the water-soluble lubricant stored in the hollow portion is pressurized to a required pressure and discharged. The discharge pipe 57 is connected to the mixing means 59.

The main body 46 is provided with a compressed air switching control means 63 comprising an electromagnetic valve, a pressure regulating valve, etc., and the compressed air switching control means 63 is composed of a pressure increasing means control section 63a and a compressed air control section 63b. The The pressure increasing means control unit 63a controls the switching of the compressed air supplied from the compressed air generation source 64 to the positive pressure chamber and the back pressure chamber of the cylinder unit 51c, and reciprocates the rod 51b. The compressed air control unit 63b controls the air pipe 65 connected to the mixing means 59 so that the compressed air is discharged at the timing when the rod 51b moves in the pressurizing direction.

As means for adjusting the pressure of the water-soluble lubricant by the pressure-increasing means 51, an operating piece (not shown) is attached to the non-operating side end of the rod 51b protruding from the cylinder 51c so that the position can be adjusted. A position detector (not shown) such as a limit switch is attached to the moving position of the rod 51b according to the desired pressure position, and the position detector is turned on by the operating piece of the rod 51b protruding when the water-soluble lubricant is pressurized. The supply of compressed air to the cylinder part 51c is cut off at the actuated timing, and the water-soluble lubricant is controlled to be pressurized with a pressure corresponding to the movement stroke of the rod 51b.

The discharge pipe 57 and the air pipe 65 described above are connected to an input port of the mixing means 59, and an output port of the mixing means 59 is connected to a supply hose 45 connected to the connection port of the metal core 43. The mixing means 59 is provided with check valves 59a and 59b in the pipes 57 and 65, respectively, and the compressed water is mixed with the water-soluble lubricant pressurized by the pressure increasing means 51 to further increase the pressure. The water-soluble lubricant that has been mixed with compressed air by the mixing means 59 and increased in pressure is discharged to the core metal 43 in a state containing countless bubbles.

A water-soluble lubricant recovery pan 69 is disposed on one end side of the metal tube 7 set in the metal tube bending apparatus 1, and the other end of the water-soluble lubricant recovery pan 69 is connected to the recovery tank 47a. One end of the discharge pipe 71 is connected by providing a pump 73 such as an electric pump or an air pump. The water-soluble lubricant collection pan 69 collects the excess water-soluble lubricant that has flowed out into the metal pipe 7 during bending and returns it to the collection tank 47a for circulation.

Next, the operation of the metal pipe bending apparatus 1 configured as described above will be described.
First, the outline of the bending action of the metal tube 7 by the metal tube bending apparatus 1 will be described. The plug 37 and the shaft member 35 are inserted into the hollow portion of the linear metal tube 7 to be bent, and the end portion is held by the holding member 29. After that, the movable body 27 is controlled to move and the bending portion of the metal tube 7 is attached to the groove 9 a of the bending die 9.

Next, the electric motor is driven to rotate the gripping member 29 around the axis of the metal tube 7 at a predetermined angle to rotate the metal tube 7. The rotation angle of the metal tube 7 is set according to the bending direction at each bending position when performing a plurality of bending processes on the metal tube 7.

Next, the clamping cylinder 17 is operated to move the clamping mold 15, and the metal tube 7 is gripped by the bending mold 9 and the clamping mold 15. Further, the pressure mold cylinder 23 is operated to move the pressure mold 21, and the metal pipe 7 is held between the wiper mold 19 and the pressure mold 21.

Next, the bending arm cylinder 13 is actuated to rotate the bending arm 11 about the bending die 9 and move the clamping die 15 around the bending die 9 to bend the metal tube 7. , The clamping die cylinder 17 is moved backward to release the holding of the metal tube 7 by the clamping die 15 and the pressure die cylinder 23 is moved backward to release the holding of the metal tube 7 by the pressure die 21. . Then, the bending arm cylinder 13 is moved back to return the bending arm 11 to the original position, and the bending process of the metal tube 7 is completed.

When the metal tube 7 is bent a plurality of times, the movable body 27 is controlled to move the bending portion of the metal tube 7 to the groove 9 a of the bending die 9. When the bending direction is different in the next bending process, the electric motor is driven and controlled, the gripping member 29 is rotated to rotate the metal tube 7 at a required angle, and then the bending is repeated by repeating the above-described operation. Processing.

Next, the operation of supplying the water-soluble lubricant will be described. For example, after the mandrel 33 for bending and thus the plug 37 and the shaft member 35 are inserted into the hollow portion of the metal tube 7 as described above, the movable body 27 is inserted. When the bending portion of the metal tube 7 is mounted in the groove 9a of the bending die 9, the clamping member 15 is moved to rotate the clamping die 15 and the bending die 9 is moved. When the metal tube 7 is gripped by the clamping die 15, when the bending arm 11 is rotated around the bending die 9 to move the clamping die 15 around the bending die 9, the clamping die 15 and the pressure die 21 are used. When releasing the gripping of the metal tube 7 and returning the bending arm 11 to the original position, the water-soluble lubricant supply means so that the water-soluble lubricant is sprayed in a mist form on the inner peripheral surface of the metal tube 7 at the 37 locations of the plug. 41 is controlled as follows.

In the present embodiment, the example in which the water-soluble lubricant is injected at each timing described above will be described. However, in the present invention, after the plug 37 and the shaft member 35 are inserted into the hollow portion of the metal tube 7. The water-soluble lubricant may be sprayed to the plugs 37 in the metal tube 7 throughout the bending process until the clamping of the metal tube 7 by the clamping die 15 and the pressure die 21 is released.

First, the compressed air switching control means 63 applies to the positive pressure chamber and the back pressure chamber of the cylinder portion 51c in the pressure increasing means 51 prior to injecting and supplying the water-soluble lubricant to the 37 locations of the plug in the metal pipe 7. Then, the compressed air is alternately supplied to reciprocate the rod 51b.

When the rod 51b is moved in the shrinking direction by the above operation, a negative pressure is formed in the pressurizing portion 51a, and the water-soluble lubricant stored in the supply tank 47c is sucked into the pressurizing portion 51a. The water-soluble lubricant in the pressurizing part 51 a is compressed and pressurized by the rod 51 b that moves in the direction of extension after being introduced, and is discharged to the discharge pipe 57. Further, the compressed air switching control means 63 discharges the compressed air to the air pipe 65 in parallel with the operation of supplying the compressed air to the positive pressure chamber of the cylinder portion 51c to reach the mixing means 59.

In the mixing means 59, the compressed air is mixed with the water-soluble lubricant pressurized by the pressure increasing means 51 and further pressurized. Then, the water-soluble lubricant pressurized as described above is supplied to the core metal 43.

When the water-soluble lubricant pressurized in the metal core 43 has a pressure equal to or lower than the elastic force of the elastic member 43b, the check ball 43a urged by the elastic force of the elastic member 43b has a small-diameter hollow portion. The water-soluble lubricant injection is regulated by being pressed against the opening and closing. Then, when the pressure in the core metal 43 in which the injection of the water-soluble lubricant is restricted by the check ball 43a urged by the elastic force of the elastic member 43b reaches a predetermined pressure, the water-soluble lubricant by the pressure increasing means 51. And the discharge of compressed air to the air pipe 65 are interrupted and made to stand by. (See Figure 3)

  When the plug 37 and the shaft member 35 are inserted into the hollow portion of the metal tube 7 before the processes of the above steps are performed in the above state, that is, when the gripping member 29 is rotated, the clamping die 15 is When moving, when rotating the bending arm 11 around the bending mold 9, when releasing the gripping of the metal tube 7 by the clamping mold 15 and the pressure mold 21, when returning the bending arm 11 to the original position, The pressure increasing means 51 is operated based on a signal from a detector provided at a location, and the water-soluble lubricant stored in the supply tank 47c is sucked into negative pressure to flow into the pressurizing portion 51a, and then expands. The water-soluble lubricant in the pressurizing portion 51a is compressed and pressurized by the rod 51b moving in the direction to be discharged and discharged to the discharge pipe 57, and the compressed air is discharged to the air pipe 65 to reach the mixing means 59.

  The water-soluble lubricant that reaches the mixing means 59 is further pressurized by the compressed air to be mixed and reaches into the cored bar 43, and the pressure of the water-soluble lubricant in the cored bar 43 exceeds the elastic force of the elastic member 43b. When the pressure is reached, the check ball 43 a moves against the elastic force of the elastic member 43 b to open the small-diameter hollow portion, thereby injecting pressurized water-soluble lubricant into the metal tube 7. (See Figure 5)

  At this time, the water-soluble lubricant injected into the metal tube 7 is pressurized to a high pressure by the compressed air discharged from the pressure-increasing means 51 and the mixing means 59, so that the inner peripheral surface of the metal tube 7 and the ball shape A water-soluble lubricant can be sprayed and applied to the plug 37 including the plug 39 over the entire surface, and the inner surface of the metal tube 7 is damaged by the plug 39 during the bending process. This prevents the bending accuracy from deteriorating due to vibration.

  It should be noted that, as described above, the water-soluble lubricant is not sprayed for each process during the bending of the metal tube 7, but the water-soluble lubricant is continuously sprayed throughout the bending work. Good.

  Of the water-soluble lubricant spray-coated on the inner peripheral surface of the metal tube 7 and the plug 37 including the spherical plug 39 as described above, the excess water-soluble lubricant is water-soluble lubricant from the end of the metal tube 7. It is discharged into the collection pan 69 and collected. When the water-soluble lubricant recovered in the water-soluble lubricant recovery pan 69 reaches a predetermined amount, the pump 73 is driven to remove the water-soluble lubricant in the water-soluble lubricant recovery pan 69 through the discharge pipe 71. After returning to the collection tank 47a, the metal powder adsorbing member 49 adsorbs and removes the metal powder, and then accumulates in the supply tank 47c for circulation.

  In this embodiment, the water-soluble lubricant pressurized by the pressure increasing means 51 can be further increased by compressed air discharged from the mixing means 59, and is pressurized using a light output pump as in the prior art. Compared to the case, the device itself can be reduced in size and weight to reduce the cost.

Further, as described above, the water-soluble lubricant is entirely applied to the inner peripheral surface of the metal tube 7 and the plug 37 including the ball-shaped plug 39 by injecting the water-soluble lubricant under high pressure. It is possible to prevent the bending accuracy from being deteriorated due to scratches on the inner surface of the metal tube 7 during the bending process or vibration of the metal tube 7.

In the above description, one pressure part 51a is provided on one side of the cylinder part 51c, and when the rod 51b moves in the shrinking direction, the rod 51b is sucked into the pressure part 51a under a negative pressure. 6 is configured as a single-acting type that compresses and pressurizes the water-soluble lubricant in the pressurizing portion 51a when moving in the extending direction, but as shown in FIG. 6, both sides in the axial direction of one cylinder portion 51c Two pressurizing parts 51a are respectively provided, and the shaft end parts of the rods 51b are respectively slidably inserted into the hollow parts of the respective pressurizing parts 51a so as to slide in the axial direction, thereby reciprocating the rod 51b with respect to the axial direction. Along with this, a double-acting type that alternately sucks the water-soluble lubricant in one pressurizing part 51a and compresses and pressurizes the water-soluble lubricant in the other pressurizing part 51a is configured. Also good.

DESCRIPTION OF SYMBOLS 1 Metal pipe bending apparatus 3 Main body 5 Bending head 7 Metal pipe 9 Bending die 9a Groove 11 Bending arm 13 Bending arm cylinder 15 Clamping die 17 Clamping cylinder 19 Wiper die 21 Pressure die 23 Pressure die cylinder 25 Rail 27 Movable body 29 Grasping member 31 Support member 33 Bending mandrel 35 Shaft member 37 Plug 39 Spherical plug 41 Water-soluble lubricant supply means 43 Core metal 43a Check ball 43b constituting a part of the opening / closing means Elastic constituting a part of the opening / closing means Member 43c Stop ring 45 Supply hose 46 Main body 47 Tank 47a Recovery tank 47b Metal powder recovery tank 47c Supply tank 47d Partition plate 47e Partition plate 49 Metal powder adsorbing member 51 Pressure increasing means 51a Pressure unit 51b Rod 51c Cylinder unit 53 Supply piping 55 Check valve 57 Discharge piping 59 Mixing means 61 Check 63 compressed air switching control means 65 air pipe 69 water-soluble lubricant recovery pan 71 discharge pipe 73 pump

Claims (3)

In a metal tube bending device that bends a metal tube by inserting a mandrel for bending into the bending portion of the metal tube,
A cylinder unit that reciprocates the rod slidably supported in the axial direction Te in the hollow portion of the pressure,
A pressure increasing means for pressurizing the water-soluble lubricant stored in the tank as the rod of the cylinder portion is reciprocated after the negative pressure is sucked into the pressurizing portion;
Mixing means for increasing the pressure by mixing compressed air with the water-soluble lubricant pressurized by the pressure increasing means;
A cored bar which is mounted in the hollow part of the bending mandrel and supplied with a water-soluble lubricant from the mixing means;
A check ball supported so as to be movable in the axial direction within the hollow portion of the core metal;
An elastic member that urges the check ball to close the hollow portion of the core metal;
Comprising a water-soluble lubricant supply means consisting of
When the pressure of the water-soluble lubricant supplied from the mixing means is lower than the elastic force of the elastic member, the water-soluble lubricant supplying means keeps the closed state of the hollow portion by the check ball while supplying from the mixing means When the pressure of the water-soluble lubricant to be applied is higher than the elastic force of the elastic member, the check ball is moved against the elastic force of the elastic member to open the hollow portion so that the water-soluble lubricant can be injected. metal pipe to bending apparatus. When injecting a water-soluble lubricant from a bending mandrel to a bending portion of a metal tube in a bending portion of the metal tube by inserting a bending mandrel into the bending portion of the metal tube and bending the metal tube,
After pressurizing the water-soluble lubricant sucked negative pressure from the tank by the pressure increasing means,
Increase the pressure by mixing compressed air with the pressurized water-soluble lubricant,
When the pressure of the increased water-soluble lubricant supplied in the hollow portion of the mandrel attached in the hollow portion of the bending mandrel is lower than the required pressure, the water-soluble lubricant is injected into the metal pipe. On the other hand, a water-soluble lubricant supplying method that enables the water-soluble lubricant to be injected into the metal pipe when the pressure of the increased water-soluble lubricant in the hollow portion of the metal core is higher than a required pressure. In claim 2,
When the check ball supported so as to be movable in the axial direction in the hollow portion of the core metal is urged by an elastic member, and the pressure of the increased water-soluble lubricant is lower than the elastic force of the elastic member, If the pressure of the increased water-soluble lubricant is higher than the elastic force of the elastic member while keeping the hollow portion closed by the check ball, the check ball is moved against the elastic force of the elastic member. A method for supplying a water-soluble lubricant that allows a water-soluble lubricant to be jetted by opening a hollow portion .

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