JP2009502511A - Molded part forming apparatus and method - Google Patents

Abstract

  An apparatus and method is provided for forming a molded part having a larger portion between a bend and an end from a tube (14) having an end and at least one bend. The molded part is formed by applying pressure fluid in the tube (14) while maintaining pressure on the end of the tube to cause expansion of the tube between the bend and end. The molded part is formed on a hydraulic press (10) having an upper mold (18) and a lower mold (16). The device (10) includes at least one side assembly (22) pivotally attached to the lower mold (16) with a cylinder (28) to apply pressure to at least one end of the tube (14). ). The apparatus further comprises a seal (34) that seals the end of the tube (14) and a fluid control device (36) that pressurizes the fluid in the tube.

Description

  The present invention relates generally to the field of forming a tubular member into a molded part using hydraulic pressure, and more particularly, from a tube, at least one bend, and one or more bends and one or more of the tube. And a method and apparatus for forming a molded part having a substantially larger cross-section at least a portion of the tube between the ends of the tube.

  The prior art discloses forming metal tubes using, for example, hydraulic pressure. For example, Garvin U.S. Pat. No. 2,892,254 ("Garvin patent") discloses a hydraulic press for forming metal parts. Hydraulic presses such as those disclosed in the Garbin patent typically have two opposing molds that close to form a cavity. The cavity defines the desired resulting shape of the part. In order to form a molded part, the tube is placed in a cavity between the dies of the hydraulic press. The mold is closed and the end of the tube is sealed. The tube is filled with liquid and then pressurized to expand the tube until it matches the shape of the cavity defined by the hydraulic press mold. In this way, the tube is expanded to form the desired molded part. It has been found that when the tube expands, the expansion of the tube is limited because the wall thickness of the expansion portion gradually decreases. In fact, it has been found that the cross section of the tube cannot be expanded beyond about 20 percent.

  The limited expansion problem has been eliminated by feeding additional tubing material from both ends into the expanding section during the expansion process. For example, US Pat. No. 5,481,892 to Roper et al. (“Roper patent”) discloses feeding additional tubing material from both ends of the tubing to the inflatable section. The system and method of the Roper patent discloses that the cross section of the tube can be expanded by as much as 100 percent. According to the system and method of the Roper patent, frictional constraints typically limit the expansion of the cross section to 50 percent.

  One drawback of the system and method disclosed by the Roper patent is that when the end of the tube is in an upright position, additional tube material is supplied into the portion that is expanding through one or more bends in the tube. That is not possible.

  Some prior art systems and methods have overcome this problem by separating the flexion and expansion processes. For example, US Pat. No. 5,353,618 to Roper et al. Discloses pre-bending, for example, a metal tube prior to the expansion step. Additional tube material can be supplied to the portion that is expanding through one or more bends in the tube so that when the tube is rotated, the end is in the same horizontal plane as the main portion of the tube It turns out that.

  One drawback of pre-bending the tube prior to expansion is that additional steps are required during the manufacturing process, additional tools and effort are required, and therefore the price per part increases. For example, the tube must first be placed in a bending device to create one or more bends. The tube must then be transported to the hydroforming device for the expansion process, which increases work hours and may require additional workers. The tube must be placed in the hydroforming device so that the end of the tube is in the same horizontal plane as the main part of the tube, which requires a larger mold to house the tube and increases manufacturing costs . In addition, by pre-bending the tube before expansion, the wall surface of the bent portion of the tube is thinned.

  Another drawback of pre-bending the tube before expansion is that thin-walled tubes often break during the expansion process. It has been found that pre-bending is only possible with tubes having a wall thickness of about 0.1651 cm (0.065 inches) or greater.

  Thus, having a single bend between the expanding portion and the end of the tube, or multiple bends on either side of the expanding portion between the expanding portion and the end of the tube There is a need for a method and apparatus that allows greater expansion of molded parts having

  According to one aspect of the invention, there is provided a method of forming a molded part from a tube having a bend and a cross section substantially larger than the original tube of at least a portion of the tube between the bend and the end. . The method includes placing a tube in a hydraulic press having upper and lower molds, sealing the end of the tube, filling the tube with liquid, and inflating a portion of the tube. Pressurizing liquid into the tube, bending the tube between the inflated portion and one end, and adjoining the bend to supply the metal to the inflated portion while the tube is bent Pushing the end of the pipe in the axial direction. As a result, the cross section of the inflatable portion can be inflated much larger while still maintaining the desired wall thickness.

  According to another aspect of the invention, there is provided an apparatus for forming a molded part from a tube having a bend and a cross section substantially larger than the original tube of at least a portion of the tube between the bend and the end. The The apparatus includes a hydraulic press having an upper mold and a lower mold, at least one sealing mechanism configured to seal an end of the pipe, a fluid control apparatus for pressurizing liquid in the pipe, and a bending section When the tube is bent while pushing the end of the tube coaxially to feed material into the part that is inflated from the portion between the end and the end, ride on the end of the tube And an assembly configured as described above. As a result, the cross section of the inflated portion can be enlarged by 65% of the original cross section while maintaining an appropriate thickness.

  The specification concludes with claims that particularly point out and distinctly claim the invention, and this is a non-limiting illustration of the best mode presently contemplated for carrying out the invention. It will be better understood from the following description in conjunction with the drawings, wherein like reference numerals designate like parts throughout the drawings.

The present invention is directed to an apparatus and method for forming a molded part from a tube having a bend and a substantially larger cross section in at least a portion of the tube between the bend and the end.
The tube may be comprised of any material that allows the formation of a substantially larger cross section in the bend and at least a portion of the tube between the bend and end. The tube is preferably composed of metal. The present invention works particularly well with common steel grades such as SAE 1008 or 1018. The present invention can also be used with difficult to form metals such as stainless steel 304L or 409 or aluminum.

  The tube thickness depends on the tube diameter and the type of material used. For example, for a tube constructed from SAE 1008 or 1018 steel and having a diameter of 2.54 cm (1 inch), the present invention has a wall thickness in the range of 0.07112 to 0.07874 cm (0.028 to 0.031 inch). Works best. As another example, for a tube constructed from stainless steel 304L and having a diameter of 2.54 cm (1 inch), the present invention works best with a wall thickness of 0.149 cm or greater.

  The tube is inflated with any type of liquid that causes the tube to expand upon pressurization. For example, the liquid can include water. Alternatively, the liquid can include a mixture or can include an additive. For example, the liquid can include a lubricant and / or a rust inhibitor. The liquid is preferably composed of about 95% water and 5% additives including lubricants and rust inhibitors.

  The present invention uses a hydraulic press that bends the tube to form a molded part. The hydraulic press has first and second molds that move between a first or open position and a second or closed position. In the first or open position, the molds are spaced either vertically or horizontally so that the tubes can be positioned between the molds. The mold is preferably configured such that the first mold is on the second mold. The first or upper mold moves vertically downward from the first or open position to the second or closed position. Alternatively, both molds move towards each other from a first or open position to a second or closed position.

  In the second or closed position, the molds engage each other thereby enclosing the tube. The upper mold preferably moves vertically downward to engage the lower mold, thereby enclosing the tube. In another method, the mold is configured such that either the first mold or the second mold moves. For example, the first mold advances vertically upward toward the second mold, or both molds move toward each other to surround the tube. In addition, the mold can be configured to move forward in the horizontal path to face the vertical path.

The mold has a matching or corresponding cavity that holds the tube. In this arrangement, the cavities define the desired shape of the tube after expansion when the molds engage each other.
The assembly holds at least one end of the tube during the bending and expansion process. The assembly is configured to do so at the end of the tube when the tube is bent. The assembly also applies pressure to the end of the tube while the tube is bent. In addition, the assembly maintains pressure on the end of the tube during the expansion process to cause expansion of the tube between the bend and the end. The assembly is attached to one of the molds so as to be pivotable (pivot and turn). The assembly is preferably attached to the lower mold.

  The assembly pivots or moves from a first or downward position to a second or upward position. The assembly begins in a first or downward position. The tube is placed between the open molds so that the end of the tube is received by the assembly. The tube is preferably received by a hole in the assembly and holds the end of the tube.

  As the tube bends, the assembly rides on the end of the tube and pivots toward the second or upward position to do so. The assembly preferably pivots about a pin aligned with the hole. The assembly pivots about the pin to a second or upward position. Thus, the assembly retains the end of the tube when bent.

  The assembly includes a cylinder that pushes the end of the tube while the tube is bent. The cylinder preferably applies a force to the locking block and holds the end of the tube via a piston rod. As the assembly pivots upward, the cylinder continues to apply force to the end of the tube. By pushing the tube, the cylinder pushes the tube into the cavity between the molds. In addition, the force applied by the cylinder at the end of the tube causes the tube to expand. The cylinder is preferably a hydraulic cylinder. Alternatively, the cylinder may be electric or hydraulic.

The cylinder applies a specific force to the tube, depending on the type of material that contains the tube.
The present invention includes a sealing mechanism that seals the end of the tube. The sealing mechanism extends over or into the end of the tube, thereby sealing the tube and allowing the tube to be pressurized by the fluid control device. The sealing mechanism is preferably a sealing cone having a tapered wall substantially similar to that disclosed in Brown US Pat. No. 6,502,822, incorporated herein by reference. The sealing mechanism is preferably composed of hardened steel, such as D2 steel, which is hardened tool steel.

  In order to form a molded part, the tube is placed between the upper and lower molds of the hydraulic press. The end of the tube is sealed by a sealing mechanism, and the tube is filled with hydroforming liquid. The tube is bent and the liquid inside the tube is pressurized by the fluid control device. The assembly supplies the tube material into the expanding portion between the bend and the end and maintains the desired thickness of the expander during the bend and expand process. Press the end of.

  While the tube is bent, the liquid inside the tube is pressurized by the fluid control device. The pressurized liquid acts as a mandrel so that the tube does not deform. The liquid is pressurized to a specific pressure or pressure range depending on the type of material comprising the tube. For most metals, the liquid is first pressurized to about 3448 kPa (about 500 pounds per square inch) and then up to about 20690 kPa (about 3000 pounds per square inch) during the bending process.

While the tube is inflated, the fluid inside the tube is pressurized by the fluid control device to be in the pressure range of 20690 kPa to 413700 kPa (3,000 to 60,000 pounds per square inch). To cause tube expansion, the liquid pressure must be above the tube yield point. In addition, the pressurized liquid must be below the lower of the pressure at which the mold separates or the burst pressure of the tube. The burst pressure P _burst is defined as follows.

Where th is the wall thickness of the tube, r is the radius of the tube, and TS is the tensile strength of the material containing the tube.
For most metals, the liquid is initially pressurized to about 3,000 pounds per square inch. During tube expansion, the pressure of the liquid is raised to about 60,000 pounds per square inch so that the tube material completely fills the cavities between the molds.

  During expansion of the tube, the tube material is fed into the expanding portion of the tube, allowing substantial expansion of the tube cross-section. For tubes constructed from stainless steel type 304L, the tube material supplied to the expanding portion of the tube preferably expands the cross section to as much as 65 percent.

  Many modifications and variations will occur to those of skill in the art upon reviewing this description. All such changes and modifications that come within the spirit of the invention are intended to be included within the scope of the claims.

  The invention will now be described more fully with reference to the drawings, which illustrate preferred embodiments of the invention. However, the subject matter of the present disclosure can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein.

  Referring now to the drawings wherein like reference numerals indicate the same or corresponding parts throughout the several views, FIG. 1 is a perspective view of a rotating hydroforming apparatus 10. The present invention is used in conjunction with a hydraulic press 12 to bend a tube 14 and form a molded part.

  1 and 3, the hydraulic press 12 has first and second molds 16, 18 shown in a first position. In the first or open position, the molds 16, 18 are spaced vertically or horizontally so that the tube 14 can be positioned between the molds. For example, as shown in FIG. 3, the molds 16, 18 are arranged in a parallel and spaced relationship so that the second or upper mold 18 is placed on the first or lower mold 16. Has been placed. The upper mold 18 moves vertically downward from the first or open position shown in FIG. 3 to the second or closed position shown in FIGS. 2 and 4.

  The first mold 16 includes a cavity 20 that holds the tube 14 and defines a portion of the desired shape of the tube after expansion, as will be described below. Similarly, the second mold 18 includes a cavity (not shown) corresponding to the cavity 20. In this arrangement, when the dies 16, 18 are engaged with each other as shown in FIG. 4, the cavity defines the desired shape of the tube 14 after expansion, as described below.

  The assembly 22 is pivotally attached to one of the molds 16,18. The assembly 22 is preferably attached to the first or lower mold 16. Alternatively, the assembly 22 can be attached to the second or upper mold 18. The assembly 22 is configured to do so at the end of the tube 14 when the tube is bent. In addition, the assembly 22 pushes the end of the tube 14 as will be described below.

  The assembly 22 is in a first or downward position in FIGS. Thus, the tube 14 can be placed between the molds 16 and 18 so that the end of the tube is received by the assembly 22. The tube 14 is preferably received by a hole 24 that holds the end of the tube.

  The cylinder 28 pushes the end of the tube 14 while the tube is bent. As shown in FIGS. 1 and 3, the cylinder 28 applies a force to the locking block 30 via a piston rod 32 that holds the end of the tube 14. As assembly 22 pivots upward, cylinder 28 continues to exert a force on the end of tube 14, as shown in FIGS. By pushing the tube 14, the cylinder 28 pushes the tube into the cavity 20. In addition, the force applied by the cylinder 28 to the end of the tube 14 controls the expansion of the tube as described below. The cylinder 28 may be hydraulic or pneumatic. The cylinder 28 is preferably a hydraulic cylinder.

The cylinder 28 applies a specific force to the tube 14 depending on the type of material comprising the tube.
2 and 4, the dies 16, 18 of the hydraulic press 12 are in the second position in the figure. In the second or closed position, the molds 16, 18 engage each other thereby enclosing the tube 14. As shown in FIG. 4, the upper mold 18 preferably moves vertically downward to engage the lower mold 16, thereby surrounding the tube 14. Alternatively, the molds 16, 18 are configured such that either the first mold 16 or the second mold 18 moves. For example, the first mold 16 can be advanced vertically upward toward the second mold 18, or both molds 16, 18 can move toward each other to surround the tube 14. it can. In addition, the molds 16, 18 can be configured to advance in the horizontal path so as to face the vertical path shown in FIG.

  Molds 16, 18 bend tube 14 when moved to the second or closed position. As the tube 14 is bent, the assembly 22 pivots to the end of the tube in the manner necessary to do so. The assembly 22 preferably pivots about a pin 26 aligned with the hole 24, as shown in FIG. Assembly 22 pivots about pin 26 to a second or upward position, as shown in FIGS. Thus, the assembly 22 holds the end of the tube 14 when bent.

  Referring now to FIG. 5, the sealing mechanism 34 is configured to seal the end of the tube. The sealing mechanism extends into the end of the tube, thereby sealing the tube and allowing the tube to be pressurized by the fluid control device 36. The sealing mechanism 34 is preferably a sealing cone having a tapered wall surface similar to that disclosed in Brown US Pat. No. 6,502,822, incorporated herein by reference. The sealing mechanism 34 is preferably composed of hardened steel, such as D2 steel, which is hardened tool steel.

  In order to form a molded part, the tube 14 is arranged between the dies 16 and 18 of the hydraulic press 12. The end of the tube 14 is sealed by a sealing mechanism 34 and the tube is filled with liquid. The tube is bent and the liquid inside the tube is pressurized by the fluid control device 36. The assembly 22 supplies tube material into the expanding portion between the bend and the end, during the bending process to maintain the desired thickness of the expanding portion during the bending and expansion process. Push the end of the tube 14.

  The tube 14 may be composed of any material having a yield point to allow the formation of a substantially larger cross section in the bend and at least a portion of the tube between the bend and the end. The tube is preferably composed of metal. The present invention works particularly well with common steel grades such as SAE 1008 or 1018. The present invention can also be used with difficult to form metals such as stainless steel 304L or 409.

  While the tube 14 is bent, the liquid inside the tube is pressurized by the fluid control device 26. The pressurized liquid acts as a mandrel so that the tube 14 does not deform. The liquid is pressurized to a specific pressure or pressure range depending on the type of material comprising the tube 14. For most metals, the liquid is first pressurized to about 3448 kPa (about 500 pounds per square inch) and then up to about 20690 kPa (about 3000 pounds per square inch) during the bending process.

  While the tube 14 is bent, the liquid inside the tube is pressurized by the fluid control device 36 above the yield point of the tube and within a range below the pressure at which the molds 16, 18 separate. . For most metals, the liquid is initially pressurized to about 3,000 pounds per square inch. During tube expansion, the pressure of the liquid is raised to about 60,000 pounds per square inch so that the tube material completely fills the cavity between the molds 16 and 18.

  During expansion of the tube 14, tube material is fed into the expanding portion of the tube, allowing substantial expansion of the tube cross-section. For tubes constructed from stainless steel type 304L, the tube material supplied to the expanding portion of the tube preferably expands the cross section to as much as 65 percent.

  Tube 14 is inflated with any type of liquid that causes the tube to expand upon pressurization. For example, the liquid can include water. Alternatively, the liquid can include a mixture or can include an additive. For example, the liquid can include a lubricant or rust inhibitor, as may be required by a particular application. The liquid is preferably composed of about 95% water and 5% additives including lubricants and rust inhibitors.

  Many modifications and variations will occur to those of skill in the art upon reviewing this description. All such changes and modifications that come within the spirit of the invention are intended to be included within the scope of the claims.

FIG. 2 is a partial perspective view of a portion of a preferred embodiment of the present invention, as shown in an open position. FIG. 3 is a partial perspective view of a portion of a preferred embodiment of the present invention, as shown in a closed position. FIG. 3 is a side plan view of a preferred embodiment of the present invention as shown in the open position. Figure 2 is a side plan view of a preferred embodiment of the present invention as shown in the closed position. FIG. 3 is a cross-sectional view of a preferred embodiment of the present invention along line AA in FIG.

Claims (23)

A method of forming a molded part from a tube, the step of placing the tube in a hydraulic press having upper and lower molds, the step of sealing the end of the tube, and filling the tube with liquid A method comprising: a step; a bending step of bending the tube; and an expansion step of pressurizing the liquid to expand at least a portion of the tube.
A step of applying a force to an end of the tube during the bending step, wherein a pipe material is supplied into an expanding portion between the bending portion and the end, and during the bending step and the expansion step Applying a force to maintain the expanded portion at a desired thickness.   The method of claim 1, wherein the tube comprises a metal.   The method of claim 1, wherein the tube comprises stainless steel.   The method of claim 1, wherein the tube comprises aluminum.   The method of claim 1, wherein the pressure inside the tube during bending ranges from 3448 kPa to 20690 kPa (500 to 3,000 pounds per square inch).   The pressure for inflating the tube is in a pressure range above the yield point of the tube and below the pressure at which the upper mold and the lower mold separate. Method.   The method of claim 2, wherein the pressure to inflate the tube ranges from 3,000 to 60,000 pounds per square inch (20690 kPa to 413700 kPa).   The method of claim 1, wherein the cross-section of the expanding portion of the tube expands to 65 percent.   The method of claim 1, wherein the liquid comprises water.   The method of claim 1, wherein the liquid comprises water, a lubricant, and a rust inhibitor. An apparatus for forming a molded part from a tube, comprising a hydraulic press having upper and lower molds, at least one sealing mechanism configured to seal the end of the tube, and applying liquid within the tube. A fluid control device for compressing,
An assembly configured to do so at the end of the tube when the tube is bent, the assembly also being tube material in an inflated portion between the bend and end And configured to apply a force to the end of the tube to maintain the inflatable portion at a desired thickness.   The apparatus of claim 11, wherein the assembly comprises a hydraulic cylinder.   The apparatus of claim 12, wherein the cylinder is pivotally attached to the lower mold.   The apparatus of claim 11, wherein the tube comprises metal.   The apparatus of claim 11, wherein the tube comprises stainless steel.   The apparatus of claim 11, wherein the tube comprises aluminum.   The apparatus of claim 11, wherein the pressure inside the tube during bending ranges from 3448 kPa to 20690 kPa (500 to 3,000 pounds per square inch).   The apparatus of claim 14, wherein the pressure to expand the tube is in a pressure range that is above the yield point of the tube and below the pressure at which the upper mold and the lower mold separate. .   15. The apparatus of claim 14, wherein the pressure to inflate the tube ranges from 3,000 to 60,000 pounds per square inch (20690 kPa to 413700 kPa).   The apparatus of claim 11, wherein the cross-section of the expanding portion of the tube expands to 65 percent.   The apparatus of claim 11, wherein the liquid comprises water.   The apparatus of claim 11, wherein the liquid includes water, a lubricant, and a rust inhibitor.   The apparatus of claim 11, wherein the sealing mechanism comprises a sealing cone, the sealing cone extending into an end of the tube to seal the tube and to pressurize the tube.

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