CZ85699A3 - Process and apparatus for producing tubular hollow body with bulges arranged at certain distance from each other - Google Patents

Abstract

The present invention relates to a method and control for manufacturing a tubular hollow body (1) with bulges arranged therein in the longitudinal direction of the hollow body apart from each other high internal pressure forming. The hollow body (1) inserted into a two-part forming tool (3) and into a hollow body (1) a sealing and support tool (14) is inserted. This includes a sealing head (15) and a supporting body (16) that are in the hollow with housing (1) always axially adjustable. This way it can define an inner section (18) in the cavity (1). For axial the progressive shifting of the hollow body (1) is then at the inner the section (13) forms a bulge. Axial offset of hollow body (1) additional bulges may form in the forming tool (3) it being possible for the hollow body (1) to be formed between two  bowing fire.

Description

Technical field

The invention relates to a method for manufacturing a tubular hollow body with spacings spaced apart using high internal pressure molding, and to an apparatus for carrying out the method.

BACKGROUND OF THE INVENTION

The deformation of the tubular hollow bodies by high internal pressure forming is known. For example, EP 0 439 764 B1 discloses a method for manufacturing hollow one-piece metal products. In this method, the tubular hollow body, as a starting mold, is expanded by the pressure of the liquid with simultaneous axial translational movement and pressed into the shape of a split forming tool.

The length of the hollow body to be deformed is limited because the free length of the yaw increases with the length of the hollow body and the axial additional displacement would lead to the formation of waves on the hollow body without further increase in internal pressure. In addition, as the internal pressure increases, the holding force required for longer lengths increases very sharply. This again leads to an increase in production costs. This familiar way

77244 (77244a.doc)

PV 866-99 9 · · · 9 9 • 9 β * * · · 9 · 9 # ♦

9999 99

99

9 9 9

9 9 9

999 999

9

9 * · thus encounters its limits, especially when more than two concavities are to be formed in a single operation.

US-A-4 788 843 further discloses a method and apparatus for hydroforming a tubular hollow body, wherein more than two concavities may be formed on a hollow body in a single operation. For this purpose, the hollow body is inserted into the forming tool, the ends of the hollow body are locked in position and sealed. Through these end-side mandrels, the hollow body is subsequently filled with fluid. Then, by means of these mandrels, the pressing pistons are inserted into the hollow body, thereby creating the necessary hydraulic internal pressure and creating bulges. U-shaped hollow bodies can also be processed in this way.

However, irrespective of whether the hollow body is straight or bent, this method has the drawback that the thickness of the wall necessarily decreases in the radial extension regions. Thus, this method can only be used to produce products in which the requirements for dimensional preservation and deformation strength play a minor role. Finally, even in this method, the length of the processable hollow body is limited.

SUMMARY OF THE INVENTION

Therefore, based on the state of the art, the object of the invention is to improve the production of tubular hollow bodies with a plurality of spacings arranged in a spaced apart manner by using high internal pressure forming while avoiding unacceptable wall thinning and to design a device suitable for this.

The method part of this task solves according to the invention

77244 (77244a.doc)

PV 856-99 • * φ ·· ·

444

4

4 44

4 4 4 4 9

4 4 4 4

44444 4

4 4 4

4444 44 44

4 of the invention in the features of claim 1.

The basic idea is to make the bulges on the hollow body sectioned. To this end, one inner section of the hollow body is sealed at one end and supported from the inside by the other end. Subsequently, the hollow body is bulged in this inner section by means of a hydraulic high internal pressure and an axial additional movement of the hollow body. The production of further bulges on the hollow body is carried out in the same manner after the corresponding axial offset of the hollow body in the forming tool.

In this way, a series of concavities can be produced in the longitudinal direction of the hollow body of virtually any length. Due to the sectional process, the hollow body becomes impossible to swivel in this cavity production. The axial additional displacement performed in each swelling process avoids undesirable thinning of the wall thickness of the hollow body. Supporting from the inside suppresses the formation of waves in the section of the hollow body which is under axial pressure. The hydraulic pressure required for deformation may be reduced. This leads to a reduction in the necessary holding forces in the forming tool, which is advantageously reflected in the manufacturing costs. Tool wear will also be reduced.

The shape and geometry of the bulges can be determined according to requirements by selecting the corresponding matrices in the forming tool. The concavities may be formed on the hollow body either radially on one side or annular around the circumference. The concavities may also be arranged circumferentially offset from one another. The process according to the invention is thus particularly well suited, for example, for the production of hollow camshafts, which can be produced in a rational and economical manner in this way.

77244 (77244a.doc)

PV 856-99 · · · · β · 4 ♦ 4 4 · 44 4 4444 _ A - 4444 ·· ···· · 4 · 4 · 4 · 4444 · 44 · 444 44 44 44 44 4

According to claim 2, the hydraulic internal pressure is introduced from the supported end of the hollow body. This measure not only results in a rationalization of the process but also improves the creative freedom in the manufacture of the hollow bodies with respect to the length of the hollow body or possible bending operations on the hollow body.

A further preferred embodiment of the method according to the invention is to be seen in the measures according to claim 3.

According to him, the hollow body bends between the production of two bulges. This allows repeatedly bent and concave hollow bodies of almost any length to be produced during repeated hydraulic deformation and bending.

According to the measure of claim 4, one or more bulges on the front side can be opened. This can be done in a variety of ways, preferably by means of a scissor cutting technique, e.g. By opening the bulges, a hollow body is formed on the hollow body.

The solution to the object in question must be seen in the features of claim 5.

The apparatus comprises a two-piece forming tool, a sealing mandrel attachable to the hollow body from the front, and also a sealing and support tool insertable into the hollow body. This sealing and supporting tool has a sealing head and a supporting body which are always axially positionable in the hollow body. The sealing head is. it is displaceable and can be attached to the inner surface of the hollow body in a liquid-tight manner. The guide position is moved to the designed position, which passes through the support body with radial clearance.

77244 (77244a.doc)

PV 856-99 © * © © * 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 ·

The positioning of the support body and the sealing head in the correct position allows for flexible adaptation with respect to the length of the tubular hollow body and also with respect to the length of the inner section, since its length varies with the axial size of the bulges.

In the embodiment according to claim 6, the sealing head consists of two plates adjustable relative to one another with a sealing insert inserted therebetween. By pressing the two plates together, the gasket forms a continuous circumferential collar which acts as a gasket and closes the hollow body in a fluid-tight manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below with the aid of schematic drawings. These include:

FIG. 1 A device according to the invention with a tubular hollow body section prior to the deformation process in vertical longitudinal section;

FIG. 2 shows a representation of FIG. 1 during the forming process;

FIG. 3 shows the device and the hollow body before forming the second bulge in a vertical longitudinal section;

FIG. 4 illustrates FIG. 3 during the forming process;

FIG. 5 shows a hollow body after a bending process in vertical longitudinal section;

77244 (77244a.doc)

PV 856-99 φ φ ♦ · · · · φ φ φ φ φ φ · · · · · · · · · · · · · · t t t t t t t Fig. 6 Hollow body and device before vertical forming in vertical longitudinal section;

FIG. 7 illustrates FIG. 6 during the forming process;

FIG. 8 shows a concave and bent hollow body in a final longitudinal section; and FIG. 9 a sealing head in partial longitudinal section.

DETAILED DESCRIPTION OF THE INVENTION

1, 1a - 1, a tubular hollow body at various processing stages is indicated in Figures 1-8. Figures 1-8 are technically simplified and are not to be construed as a measure.

Figure 1 shows the tubular hollow body 1 in its initial position. The longitudinal section 2 of this tubular hollow body 1 is captured by a forming tool 3, which consists of an upper die A and a lower die 2. A contour 4, 2 for forming the tubular hollow body 1 is formed into these dies 4, S '. a forming tool 3 provided in the length region 3. with a radial extension 2 · The contouring sections 10, 11 which border this extension externally support the length section 2 of the tubular hollow body 1 clamped by the forming tool 3. At the end of the length section 2 is a forming tool. 3. open and has a radial extension 12 with a conical transition 13 on the orifice side.

A sealing and support tool 14 is inserted into the length section 2 of the hollow body 2. The sealing and support tool 14 comprises a sealing head 15, a support body 16, and a guide rod

77244 (77244a.doc)

PV 856-99

999 · · 9,999

999 9 9 99 99 999 999

9999 «12 9

9999 99 99 99 99 99

The axial position of the sealing head 15 and the supporting body 16 is always adjustable in the hollow body 1. For positioning, the sealing head 15 is connected to a guide rod 17 passing through the support body 16 with radial clearance.

The inner section 18, which is located in the longitudinal region 6, is sealed at one end 19 by means of the sealing and support tool 14 by the sealing head 15 and at the other end 20 by the support body 16.

The sealing head 15 includes two plate 21. 21 adjustably with respect to ^one another gasket 22 interposed between them (see. Also figure 9). 21st adjustment plates 21 ^one another in the axial direction forms a gasket 22 on the radial outer side 23 of the sealing head 15 of a circumferential sealing collar 24 which abuts the inner surface 25 of the hollow body 1 and a sealing head 15 anchors. The axial length L of the sealing head 15 is not greater than two thirds of the length L1 of the contour section 11 of the forming tool 1.

To produce a bulge on the hollow body 1, the length section 2 of the tubular hollow body 1 seals on its end side a liquid-tight piston-like sealing mandrel 26. A high internal hydraulic pressure is provided in the length section 28 sealed by the sealing head 15 and the sealing mandrel 26, which also includes an inner section 18, via an axial channel 27 guided by the sealing mandrel 26.

Figure 2 shows, in vertical longitudinal section, the representation of Figure 1 during the process of deforming the tubular hollow body 1. In this case, the sealing mandrel 26 moves the tubular hollow body 1 axially in the direction of the inner section

18. wherein the high internal hydraulic is simultaneously introduced

77244 (77244a.doc)

PV 856-99 • 0 · · 00 · 0 0 0 ·

0 0 ·

0 0 0 0 0

0 0

0000 00 * 0

0 0

0 0

000 000 0 0

The pressure leads to the formation of a concave 29 on the hollow body 1a. The support body 16 prevents the hollow body 1a from deflecting during this subsequent displacement. The subsequent manufacturing step of Figure 3 shows how the shaped hollow body 1a is offset axially in the plane of the figure to the right and the sealing mandrel 26 with the sealing head 15 delimits the new length section 28a and the sealing head 15 with the support 17, the inner section 18a.

Figure 4 shows how the second bulge 30 is positioned on the tubular hollow body 1b in the following production sequence. The forming process is identical to that described with the figure.

5 shows a hollow body 1c. which arose after the bending deformation from the hollow body 1b of Figure 4.

As shown in Figure 6, the hollow body portion 1c, not yet deformed, is inserted into the forming tool.

Figure 7 shows the molding of Figure 2, in which a further bulge 32 is formed.

The hollow body 1d is axially offset according to the manufacturing steps in Fig. 3 and Fig. 4 and the last bulge 33 is formed.

Figure 8 shows in vertical longitudinal section a tubular hollow body 1e. 1 to 7, in the final state after internal high-pressure forming. This bent hollow body is provided with concavities 29. 30, 32, 33 can then be brought to

77244 (77244a.doc)

PV 856-99 • 4 • 4 • 4

4 4 4 4

444 * 4 5

4 4 4 • 444 · 44 • 444 • 4 44

4 4 4 4

4 4 4

444 444

4 4 any further processing required.

Claims (6)

PATENT CLAIMS A method of manufacturing a tubular hollow body (1, lale) with concavities (29, 30, 32, 33) spaced apart in the longitudinal direction of the hollow body (1, la-le) using internal high-pressure forming with at least local external support in two-piece molding tool (3), characterized in that at one end (19) one inner section (18) of the hollow body (1, 1a-le) is sealed and supported at the other end (20) from the inside and at this end an inner section (18) is formed by a hydraulic high internal pressure when the hollow body (1, lale) is axially displaced, then the hollow body (1, la-le) is formed in the forming tool (3) in the same manner another effector (30, 32, 33). Method according to claim 1, characterized in that the hydraulic high internal pressure is introduced from the supported end (20) of the hollow body (1, 1a-1e). Method according to claim 1 or 2, characterized in that the hollow body (1, 1a-1e) is bent between the formation of the two bulges (30, 32). Method according to one of Claims 1 to 3, characterized in that the bulges (29, 30, 32, 33) open at the front. Device for carrying out the method according to any one of claims 1 to 4, with a two-part forming tool (3) and a sealing mandrel (26) mounted on the front side of the hollow body (1). 16 77244 (77244a.doc) PV 856-99 · · · · · • • · φ φ φ φ φ φ · · · · · · · · · · · · · · · · · · · · · · · φφ la-le), characterized in that the sealing and supporting tool (14) insertable into the hollow body (1, la-le) comprises a sealing head (15) and a supporting body (16), which are each in the hollow body (1). , la-le) axially positionable, the sealing head (15) being adjustable by a guide rod (17) passing through the radial clearance support body (16) and being fluid-tightly attachable to the inner surface (25) of the hollow body (1, la-le) . Device according to claim 5, characterized in that the sealing head (15) has two plates (21, 21 ') that can be adjusted relative to one another with a sealing insert (22) interposed therebetween.