KR20080036589A - Method and apparatus for forming molded parts - Google Patents

Abstract

An apparatus and method are provided for forming a molded part having an enlarged portion between the bend and the end from a tube 14 having an end and at least one bend. The molded part is formed by inducing expansion of the tube between the bend and the end by applying a pressure fluid in the tube 14 while maintaining pressure on the end of the tube. The molded part is formed on a hydraulic press 10 having an upper die 18 and a lower die 16. The apparatus 10 includes at least one side assembly 22 pivotally mounted to the lower die 16, having a cylinder 28 for applying pressure to at least one end of the tube 14. . The apparatus further includes a seal 34 for sealing the end of the tube 14 and a fluid control device 36 for pressurizing the fluid in the tube.

Description

Method and apparatus for forming molded part {APPARATUS AND METHOD FOR FORMING SHAPED PARTS}

FIELD OF THE INVENTION The present invention relates generally to the field of forming tubular members into molded parts using hydraulic pressure, and more particularly to at least one bend and at least a portion of the pipe between the bends or bends and the end or ends of the pipe. A method and apparatus for forming a molded part from a tube having a substantially larger cross-section in a tube.

The prior art discloses forming a metal tube by way of example using a hydraulic press. As an example, US Pat. No. 2,892,254 to Garvin discloses a hydraulic press for molding metal parts. Hydraulic presses, as disclosed in the Gavin patent, generally have two opposing dies closed to form a cavity. The cavity defines the desired final shape of the part. To form the molded part, a tube is placed in the cavity between the dies of the hydraulic press. The die is closed and the end of the tube is sealed. The tube is filled with liquid, which is then pressurized to expand the tube until the tube matches the shape of the cavity defined by the die of the hydraulic press. In this way, the tube is expanded to form the desired molded part. When the tube is inflated, it has been found that the expansion of the tube is limited because the wall thickness of the expanded portion gradually becomes thinner. In fact, it has been found that the cross section of the tube cannot be expanded by more than about 20%.

The problem of limited expansion has been overcome by supplying additional tubing material from both ends into the expansion portion during the expansion process. As an example, US Pat. No. 5,481,892 ("Roafer Patent") to Roper et al. Discloses supplying additional tubing material from both ends of the tubing into the inflation portion. The system and method of the loafers patent disclose that the cross section of the tube can be expanded by 100%. However, according to the loafers patent system and method, the expansion of the cross section is usually limited to 50% due to frictional constraints.

One disadvantage of the systems and methods disclosed in the loafers patent is that when the end of the tube is in an upright position, it is not possible to feed additional tubing material past the bend or bends in the tube into the expanded portion.

Some prior art systems and methods have overcome this problem by separating the flexion and expansion steps. By way of example, US Pat. No. 5,353,618 to Loafer et al. Discloses pre-bending a metal tube, eg, prior to the expansion step. When rotating the tube so that the end is in the same horizontal plane as the main part of the tube, it has been found that additional tubing material can be fed into the expanded portion past the bend or bend in the tube.

One disadvantage of pre-bending the tube prior to expansion is that the manufacturing process requires additional manufacturing steps, which require additional processing and labor, thus increasing the price per part. As an example, a tube must first be placed in the bend to form the bend or bends. The tube must then be transferred to a hydraulic forming apparatus for the expansion phase, which increases labor time and may even require additional workers. Since the tube must be placed in the hydraulic forming apparatus such that the end is in the same horizontal plane as the main part of the tube, a larger die is required to accommodate the tube, which increases manufacturing costs. In addition, pre-curving the tube prior to expansion causes thinning of the wall at the bend of the tube.

Another disadvantage of pre-bending the tube prior to expansion is that during the expansion phase a tube with thin walls is often cracked. Pre-bending has been found to be possible only in tubes with wall thicknesses greater than about 0.165 cm (0.065 in).

Accordingly, there is a need for a method and apparatus that has a bend between an inflation portion and an end of a tube or that enables greater expansion of a molded part having a bend on either side of the inflation portion between the inflation portion and the end of the tube. .

According to one aspect of the present invention, a method is provided for forming a bent portion and a molded part having at least a portion of the tube between the bent portion and the end having a cross section substantially larger than the original tube. The method includes placing a tube in a hydraulic press having an upper die and a lower die, sealing the end of the tube, filling the tube with liquid, and pressurizing the liquid to expand a portion of the tube. And bending the tube between the inflation portion and one end, and axially pushing on the end of the tube adjacent the bend to supply metal into the inflation portion while the tube is bent. As a result, the cross section of the expanded portion can be expanded more while still maintaining the desired wall thickness.

According to another aspect of the present invention, an apparatus is provided for forming a bent portion and a molded part having a substantially larger cross section in at least a portion of the tube between the bent portion and the end portion. The apparatus comprises a hydraulic press having an upper die and a lower die, at least one sealing mechanism configured to seal the end of the tube, a fluid control device for pressurizing the liquid in the tube, and a material from the portion between the bend and the end into the expansion portion. And an assembly configured to mount over the end of the tube and follow the end of the tube when the tube is bent while applying pressure coaxially on the end of the tube for supply. As a result, the cross section of the expanded portion can be expanded by 65% of the original cross section while maintaining the proper thickness.

Although this specification ends with the claims that particularly point out and explicitly claim the invention, it is made in conjunction with the accompanying drawings which illustrate, in a non-limiting manner, the best mode presently contemplated for carrying out the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be more clearly understood from the following detailed description, in which like reference numerals indicate like parts throughout.

1 is a partial perspective view of a portion of a preferred embodiment of the present invention, shown in an open position.

2 is a partial perspective view of a portion of the preferred embodiment of the present invention, shown in the closed position.

3 is a side elevation view of the preferred embodiment of the present invention, shown in an open position.

4 is a side elevation view of the preferred embodiment of the present invention, shown in the closed position.

5 is a cross-sectional view of the preferred embodiment of the present invention, taken along line A-A in FIG.

The present invention relates to an apparatus and a method for forming from a tube a bend and a molded part having a substantially larger cross section in at least a portion of the tube between the bend and the end.

The tube can be made of a bend and any material that allows for the formation of a substantially larger cross section in at least a portion of the pipe between the bend and the end. The tube is preferably composed of metal. The present invention applies particularly well to general steel grades such as SAE 1008 or 1018. In addition, the present invention can also be used with difficult metals such as stainless steel 304L or 409 or aluminum.

The wall thickness of the tube depends on the type of material used and the diameter of the tube. As an example, for a tube made of SAE 1008 or 1018 steel and having a diameter of 2.54 cm (1 in), the present invention best applies to wall thicknesses in the range of 0.071 to 0.078 cm (0.028 to 0.031 in). As another example, for a tube made of 304L stainless steel and having a diameter of 2.54 cm (1 in), the present invention best applies to wall thicknesses of 0.149 cm (0.049 in) or more.

The tube is expanded using any type of liquid that provides expansion of the tube upon pressurization. By way of example, the liquid may comprise water. Alternatively, the liquid may comprise a mixture or may contain additives. By way of example, the liquid may comprise a lubricant and / or a rust inhibitor. The liquid preferably consists of about 95% water and 5% additives including lubricants and rust inhibitors.

The present invention uses hydraulic presses to bend tubes and form molded parts. The hydraulic press has first and second dies moving between a first or open position and a second or closed position. In the first or open position, the dies are spaced apart in either the vertical or horizontal direction, so that a tube can be disposed between the dies. The die is preferably configured such that the first die is above the second die. The first or upper die moves vertically downward from the first or open position to the second or closed position. Alternatively, both dies move towards each other from the first or open position to the second or closed position.

In the second or closed position, the dies engage with each other and thereby receive the tube. The upper die moves vertically downward to engage the lower die, thereby receiving the tube. Alternatively, the die is configured to move the first die or the second die. For example, the first die moves vertically upwards toward the second die, or both dies move toward each other to receive the tube. In addition, the die may be configured such that the die moves in a horizontal path instead of in a vertical path.

The die has a mating or corresponding cavity holding the tube. In this arrangement, when the dies engage with each other, the cavity defines the shape of the desired tube after expansion.

The assembly retains at least one end of the tube during the bending or inflation step. The assembly is configured to follow 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. Additionally, the assembly maintains pressure on the end of the tube during the expansion step to cause expansion of the tube between the bend and the end. The assembly is pivotally mounted relative to one of the dies. The assembly is preferably mounted to the lower die.

The assembly pivots or moves from the first or downward position to the second or upward position. The assembly starts in the first or downward position. The tube is placed between the die that are open so that the end of the tube is received by the assembly. The tube is preferably received by a bore in the assembly that holds the end of the tube.

When the tube is bent, the assembly is pivoted toward the second or upward position to ride on the end of the tube and follow the end of the tube. The assembly is preferably pivoted about a pin aligned with the bore. The assembly is pivoted in the second or upward position relative to the pin. In this way, the assembly holds the end of the tube when the tube is bent.

The assembly includes a cylinder that pushes the end of the tube while the tube is bent. The cylinder preferably via the piston rod exerts a force on the locking block which holds the end of the tube. When the assembly is pivoted upward, the cylinder continually exerts a force on the end of the tube. By pushing the tube, the cylinder pushes the tube into the cavity between the dies. In addition, the force exerted on the end of the tube by the cylinder causes the tube to expand. The cylinder is preferably a hydraulic cylinder. Alternatively, the cylinder may be electric or pneumatic.

The cylinder exerts a specific force on the tube, depending on the type of material making up the tube.

The present invention includes a sealing mechanism for sealing the end of the tube. The sealing mechanism extends over the end of the tube or into the end of the tube, thereby sealing the tube and allowing the tube to be pressed by the fluid control device. The sealing mechanism is a sealing cone with 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.

To form the molded part, a tube is placed between the upper and lower dies of the hydraulic press. The end of the tube is sealed by a sealing mechanism, and the tube is filled with a hydraulic molding liquid. The tube is bent and the liquid inside the tube is pressurized by the fluid control device. The assembly presses the end of the tube during the bending process to feed the tubing material into the inflation portion between the bend and the end to maintain the desired thickness of the inflation portion during the bending and inflation steps.

While the tube is bent, the liquid inside the tube is pressurized by the fluid control device. Pressurized liquid functions as a mandrel to prevent deformation of the tube. The liquid is pressurized to a specific pressure or pressure range depending on the type of material making up the tube. For most metals, the liquid is initially pressurized to about 3.45 Mpa (500 psi) and then raised to about 20.68 Mpa (3,000 psi) during the bending step.

While the tube is inflated, the liquid inside the tube is pressurized by the fluid control device to be within a pressure range of 20.68 to 413.69 Mpa (3,000 to 60,000 psi). In order to cause the tube to expand, the pressure of the liquid must be higher than the yield point of the tube. In addition, the pressurized liquid must be lower than the pressure at which the die separates or the bursting pressure of the tube. The burst pressure (P _burst) is defined as

P _burst = (2 x th x TS) ÷ (2 xr)

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 comprising the tube.

For most metals, the liquid is initially pressurized to about 20.68 Mpa (3,000 psi). During expansion of the tube, the pressure of the liquid is increased to about 413.69 Mpa (60,000 psi), allowing the tube material to completely fill the cavity between the dies.

During the expansion of the tube, the tube material is supplied to the expanded portion of the tube, which allows for significant expansion of the cross section of the tube. In a tube made of stainless steel type 304L, the tube material supplied to the expanded portion of the tube causes the cross section to expand by 65%.

Those skilled in the art having the benefit of this description may devise many variations and modifications. All such modifications and variations that fall within the spirit of the invention are included within the scope of the claims.

Good Example  Explanation

The present invention will now be described in more detail with reference to the drawings, in which preferred embodiments of the invention are shown. However, the subject matter of this disclosure may be embodied 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 designate the same or corresponding parts throughout the several views, FIG. 1 is a perspective view of a rotating hydraulic forming apparatus 10. The invention is used in conjunction with a hydraulic press 12 to bend the tube 14 and form a molded part.

1 and 3, the hydraulic press 12 has first and second dies 16, 18 shown in the first position. In the first or open position, the dies 16, 18 are spaced apart in either the vertical or horizontal direction so that the tube 14 can be disposed between the dies. For example, as shown in FIG. 3, the dies 16, 18 are disposed in parallel spaced relation to one another such that a second or upper die 18 is disposed above the first or lower die 16. have. The upper die 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 die 16 includes a cavity 20, which holds the tube 14, as described below, and forms a portion of the desired shape of the tube after expansion. Similarly, the second die 18 includes a cavity (not shown) corresponding to the cavity 20. In this arrangement, as shown in Fig. 4, when the dies 16 and 18 engage with each other, the cavity forms the desired shape of the tube 14 after expansion, as described below.

The assembly 22 is pivotally mounted to one of the dies 16, 18. The assembly 22 is preferably mounted to the first or lower die 16. Alternatively, assembly 22 may be mounted to second or upper die 18. The assembly 22 is configured to follow the end of the tube 14 when the tube is bent. In addition, assembly 22 pushes the end of tube 14, as described below.

Assembly 22 is shown in a first or downward position in FIGS. 1 and 3. In this way, the tube 14 can be disposed between the dies 16, 18 such that the end of the tube is received in the assembly 22. The tube 14 is received by a bore 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 on the locking block 30, which holds the end of the tube 14, via the piston rod 32. As shown in Figures 2 and 4, when the assembly 22 is pivoted upward, the cylinder 28 continues to exert a force on the end of the tube 14. By pushing the tube 14, the cylinder 28 pushes the tube into the cavity 20. In addition, the force acting on the end of the tube 14 by the cylinder 28 controls the expansion of the tube, as described below. Cylinder 28 may be hydraulic or pneumatic. The cylinder 28 is preferably a hydraulic cylinder.

The cylinder 28 exerts a specific force on the tube 14, depending on the type of material comprising the tube.

Referring now to FIGS. 2 and 4, the dies 16, 18 of the hydraulic press 12 are shown in the second position. In the second or closed position, the dies 16, 18 engage with each other, thereby receiving the tube 14. As shown in FIG. 4, it is preferable that the upper die 18 move vertically downward to engage the lower die 16, thereby receiving the tube 14. Alternatively, the dies 16 and 18 are configured to move each of the first die 16 or the second die 18. By way of example, the first die 16 may move vertically upwards toward the second die 18, or both the dies 16, 18 may move toward each other to receive the tube 14. Additionally, the dies 16, 18 can be configured to move the dies 16, 18 in a horizontal path, as opposed to the vertical path shown in FIG. 4.

The dies 16, 18 bend the tube 14 as the die moves to the second or closed position. When the tube 14 is bent, the assembly 22 pivots in the manner necessary to follow the end of the tube. Assembly 22 preferably pivots about pin 26 that is aligned with bore 24, as shown in FIG. The assembly 22 pivots in the second or upward position relative to the pin 26, as shown in FIGS. 2 and 4. In this way, the assembly 22 holds the end of the tube 14 when the tube is 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 a sealing cone having a tapered wall substantially similar to that disclosed in Brown, US Pat. No. 6,502,822, which is incorporated herein by reference. The sealing mechanism 34 preferably consists of hardened steel, such as D2 steel, which is hardened tool steel.

In order to form the molded part, the tube 14 is disposed between the dies 16, 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 fluid. The tube is bent and the liquid inside the tube is pressurized by the fluid control device 36. The assembly 22 presses the end of the tube 14 during the bending process to feed the tubing material into the inflation portion between the bend and the end to maintain the desired thickness of the inflation portion during the bending and inflation steps.

The tube 14 can be composed of any material having a bend and a yield point that allows formation of a substantially larger cross section in at least a portion of the tube between the bend and the end. The tube is preferably composed of metal. The present invention applies particularly well to general 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 functions as a mandrel to prevent the tube 14 from deforming. The liquid is pressurized to a certain pressure or pressure range depending on the type of material comprising the tube 14. For most metals, the liquid is initially pressurized to about 3.45 Mpa (500 psi) and then raised to about 20.68 Mpa (3,000 psi) during the bending step.

While the tube 14 is inflated, the liquid inside the tube is pressurized by the fluid control device 36 within a range above the yield point of the tube and below the pressure at which the dies 16 and 18 are separated. For most metals, the liquid is initially pressurized to about 20.68 Mpa (3,000 psi). During expansion of the tube, the pressure of the liquid is increased to about 413.69 Mpa (60,000 psi) to allow the tube material to completely fill the cavity between the dies 16, 18.

During expansion of the tube 14, the tube material is supplied to the expanded portion of the tube, which allows for significant expansion of the cross section of the tube. Preferably, in a tube of stainless steel type 304L, the tube material supplied to the expanded portion of the tube causes the cross section to expand by 65%.

Tube 14 may be inflated using any type of liquid that provides expansion of the tube upon pressurization. By way of example, the liquid may comprise water. Alternatively, the liquid may comprise a mixture or may contain additives. By way of example, the liquid may comprise a lubricant or a rust inhibitor as the particular application requires. The liquid preferably consists of about 95% water and 5% additives including lubricants and rust inhibitors.

Those skilled in the art having the benefit of this description may devise many variations and modifications. All such modifications and variations that fall within the spirit of the invention are included within the scope of the claims.

Claims (23)

Placing the tube in a hydraulic press having an upper die and a lower die, sealing the end of the tube, filling the tube with liquid, bending the tube, and expanding at least a portion of the tube. A method of forming a molded part from a tube, comprising pressurizing a liquid, the method comprising: A method of forming a molded part, characterized by applying a force to an end of the tube during the bending step to supply the tubing material to the expansion portion between the bend and the end to maintain the required thickness of the expansion portion during the bending and expansion steps. 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 is in the range of 3.45 Mpa (500 psi) to 20.68 Mpa (3,000 psi). The method of claim 2, wherein the pressure for expanding the tube is within a pressure range that exceeds the yield point of the tube and is below a pressure at which the upper die and the lower die separate. The method of claim 2, wherein the pressure for expanding the tube is in a pressure range of 20.68 Mpa (3,000 psi) to 413.69 Mpa (60,000 psi). The method of claim 1, wherein the cross section of the expanded portion of the tube is expanded by 65%. 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 an upper die and a lower die, at least one sealing mechanism configured to seal an end of the tube, and a fluid control device for pressurizing the liquid in the tube. , When the tube is bent, comprising an assembly configured to follow an end of the tube, And the assembly is configured to apply a force to an end of the tube to supply tube material to the inflation portion between the bend and the end to maintain the required thickness of the inflation portion. The apparatus of claim 11, wherein the assembly comprises a hydraulic cylinder. The apparatus of claim 12, wherein the cylinder is pivotally mounted to the lower die. The apparatus of claim 11, wherein the tube comprises a 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 is in the range of 3.45 Mpa (500 psi) to 20.68 Mpa (3,000 psi). 15. The apparatus of claim 14, wherein the pressure for expanding the tube is within a pressure range that exceeds the yield point of the tube and is below a pressure that separates the lower die and the upper die. The apparatus of claim 14, wherein the pressure for expanding the tube is in a pressure range of 20.68 Mpa (3,000 psi) to 413.69 Mpa (60,000 psi). The apparatus of claim 11, wherein the cross section of the expanded portion of the tube is expanded by 65%. The apparatus of claim 11, wherein the liquid comprises water. The apparatus of claim 11, wherein the liquid comprises water, a lubricant, and a rust inhibitor. The apparatus of claim 11, wherein the sealing mechanism comprises a sealing cone configured to seal the tube and extend into the end of the tube to allow the tube to be pressurized.

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