Apparatus and method for reducing the cross-sectional area of ​​a tubular hollow body by deformation processing of the hollow body.

Abstract

The device (1) for reducing the cross-section of a tubular hollow body (2) having a hollow body wall (3) made of a plastically deformable material and a hollow body axis (4) extending in the longitudinal direction of the hollow body (2) comprises a forming die (5) for arrangement on the outer surface of the hollow body (2), a mandrel (6) for arrangement inside the hollow body (2), and a forming drive (8) including a mandrel drive (9) and a die drive (10). The forming die (5) is provided with a die opening (7) having an opening cross-section smaller than the hollow body cross-section of the hollow body (2) in the starting state. The forming die (5) arranged on the outer surface of the hollow body (2) is movable relative to the hollow body (2) in the direction of the axial die movement (14) along the hollow body axis (4) by means of the die drive (10) while reducing the cross-section of the hollow body (2). A mandrel (6) arranged inside the hollow body (2) is movable along the hollow body axis (4) with an axial mandrel movement counter to the axial die movement by means of a mandrel drive (9). In this case, the hollow body wall (3) is subjected to a tensile load by the mandrel (6) in the direction of the axial mandrel movement (13), and the hollow body wall (3) is pulled through the die opening (7) in the direction of the axial mandrel movement (13) against a forming die (5) arranged on the outer surface of the hollow body (2). By means of a drive control device (11) of the forming drive (8), the mandrel drive (9) and the die drive (10) can be controlled so that the axial mandrel movement and the axial die movement are superimposed on each other. By means of the above-mentioned device (1), a method for reducing the cross-section of a tubular hollow body (2) is carried out.

Description

Technical Field

[0001] The present invention relates to an apparatus for reducing the cross-section of a tubular hollow body by deformation of the hollow body, the hollow body having a hollow body wall made of a plastically deformable material and a hollow body axis extending in the longitudinal direction of the hollow body, a deformation die formed to be arranged on the outer surface of the hollow body, the deformation die having a die opening formed to receive the hollow body and having an opening cross-section smaller than the hollow body cross-section of the hollow body in the starting state, a mandrel formed to be arranged inside the hollow body, a deformation drive device having a die drive device and a drive control device, and comprising, The deformation die arranged on the outer surface of the hollow body is movable relative to the hollow body in the direction of the axial die movement along the hollow body axis while reducing the cross-section of the hollow body by using the die drive device. The invention relates to an apparatus.

[0002] The present invention further relates to a method for reducing the cross-section of a tubular hollow body by deformation of the hollow body, the hollow body having a hollow body wall made of a plastically deformable material and a hollow body axis extending in the longitudinal direction of the hollow body, arranging a deformation die on the outer surface of the hollow body, the deformation die having a die opening formed to receive the hollow body and having an opening cross-section smaller than the hollow body cross-section of the hollow body in the starting state, arranging a mandrel inside the hollow body, moving the deformation die arranged on the outer surface of the hollow body relative to the hollow body in the direction of the axial die movement along the hollow body axis while reducing the cross-section of the hollow body by using the die drive device. The invention relates to a method.

Background Art

[0003] The prior art of the form described at the beginning is known through actual use. For example, a steering shaft for an automobile, formed as a hollow shaft, is manufactured by reducing the diameter of the raw shaft using the apparatus and method described at the beginning.

[0004] In operational settings, undesirable crushing of hollow bodies where the cross-section should be reduced has been observed in several relevant cases when using known methods and apparatus. To prevent the crushing of hollow bodies, additional reinforcing materials provided to the mandrel and deformation die can be used for the hollow bodies, which surround the outer surface of the hollow body and support it radially. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide an apparatus and method that enables the reduction of the cross-sectional area of ​​a tubular hollow body with as little structural effort as possible, in particular, without additional reinforcement of the hollow body to be processed, and with reliable functionality and high-quality processing results. [Means for solving the problem]

[0006] According to the present invention, this problem is solved by the apparatus according to claim 1 and by the method according to claim 11.

[0007] In the present invention, the deformation drive device includes a mandrel drive device in addition to a die drive device. The deformation die, positioned on the outer surface of the hollow body, is actively moved along the axis of the hollow body by axial die motion using the die drive device. The undeformed hollow body, as it exists in the starting state, has dimensions larger than the opening cross-section of the deformation die opening ("calibration section") formed to produce a die opening, i.e., a reduced hollow body cross-section. Based on the active motion of the deformation die on the hollow body, the hollow body wall loaded by the deformation die is actively compressed by the deformation die in the direction of the axial die motion. At the same time, the hollow body wall is subjected to tensile load in the direction of the axial mandrel motion, on the side loaded by the deformation die, located in the direction of the axial mandrel motion, by axial mandrel motion in the opposite direction to the axial die motion.

[0008] What is important in the present invention is the superposition of the active axial mandrel motion, which is realized by the drive control of the deformation processing drive device according to the present invention, and the active axial die motion of the deformation processing die positioned on the outer surface of the hollow body. Due to the superposition of the above two motions, the compressive stress generated across the wall cross-section of the hollow body wall due to the load from the deformation processing die is at least partially canceled out by the tensile stress in the hollow body wall generated by the active axial mandrel motion.

[0009] If the compressive load on the hollow body by the deformation die and the tensile load on the hollow body by the mandrel are estimated appropriately, for example empirically, and adjusted accordingly, undesirable crushing of the hollow body wall on the side of the deformation die that loads the hollow body wall, in the direction of the axial die motion, can be reliably prevented without additional reinforcement of the hollow body. At the same time, a high deformation processing speed can be obtained by the superposition of active die motion and active mandrel motion.

[0010] Generally, axial mandrel motion and axial die motion can be controlled by position and force.

[0011] The deformation speed of the apparatus and method according to the present invention is largely independent of the material strength of the hollow body to be deformed. While a relatively high deformation force is indeed required for high-strength materials, the tendency of a hollow body made of a high-strength material to collapse is relatively low. Conversely, a tubular hollow body made of a low-strength material has a relatively high tendency to collapse, but reduction of the cross-sectional area of ​​such a hollow body is already possible with a relatively low deformation force.

[0012] In the sense of the present invention, reduction in cross-section means, when the thickness of the hollow body wall remains unchanged, a reduction in the cross-section of the hollow chamber (or the inner diameter of the pipe in the case of a cylindrical pipe) of the hollow body to be deformed, or If the cross-section of the hollow chamber of the hollow body remains unchanged, then the decrease is solely due to a reduction in the thickness of the hollow body wall, or It should be understood that this involves reducing both the cross-sectional area of ​​the hollow chamber and the thickness of the walls of the hollow body to be deformed.

[0013] Special configurations of the apparatus according to claim 1 and the method according to claim 11 are evident from dependent claims 2 to 10.

[0014] According to claim 2, a preferred configuration of the present invention provides a stationary axial support for the hollow body, which supports the hollow body when it is loaded by a deformation die in the direction of axial die motion.

[0015] According to claim 3, in the present invention, a drive control device for the deformation drive device is used to adjust the ratio of the axial mandrel motion speed to the axial die motion speed of the deformation die positioned on the outer surface of the hollow body, so as to depend on the ratio of the cross-section of the hollow body in the starting state to the decreasing cross-section of the hollow body. Depending on the degree of deformation, the value of the axial die motion speed of the deformation die positioned on the outer surface of the hollow body may be greater than, but may also be less than, the value of the axial mandrel motion speed. Within the scope of experimental use of the present invention, high-quality machining results were achieved with die speeds of 30 mm / sec to 60 mm / sec and mandrel speeds of 21 mm / sec to 43 mm / sec.

[0016] According to claim 4, in a further configuration of the present invention, the ratio of the amount of axial mandrel motion to the amount of axial die motion during deformation is inverse to the ratio of the velocity of axial mandrel motion to the velocity of axial die motion during deformation. This ensures that the active mandrel motion and deformation die motion performed over the deformation length for deformation of a hollow body terminate simultaneously when the deformation length is reached, even though the mandrel and deformation die have different velocities.

[0017] Claim 5 describes a more advantageous configuration of the present invention, wherein the deformation die is movable by positioning motion using a die drive device from a position away from the hollow body to be deformed to a position where the deformation die is positioned on the outer surface of the hollow body, and the die drive device and the mandrel drive device are controlled by a drive control device of the device drive device such that the deformation die loads the hollow body wall based on the positioning motion after the mandrel drive device has started axial mandrel motion. Thus, when the deformation die first contacts the hollow body to be deformed, the mandrel and the hollow body, which is driven along the hollow body axis by the mandrel and subjected to tensile load during the deformation process, have already been moved. Preferably, the positioning motion of the deformation die is performed in the direction of axial die motion.

[0018] The speed of the axial mandrel motion and the positioning motion of the deformation die prior to loading the hollow body wall by the deformation die can be significantly higher than the speed during the deformation process. Therefore, the mandrel containing the hollow body and / or the deformation die can be moved at high speed to a position where the deformation die contacts the hollow body wall for subsequent processing of the hollow body.

[0019] The configuration of the present invention according to claim 6 is designed based on the cross-sectional ratio according to the present invention for reducing the cross-sectional area of ​​a hollow body by reducing the thickness of the hollow body wall.

[0020] According to claim 7, in a further configuration of the invention, the reduction of the cross-section of the hollow body involves additional shaping of the hollow body wall on the outer and / or inner surface of the hollow body wall. Simultaneously with the cross-section reduction, preferably, an outer tooth row and / or an inner tooth row of the hollow body whose cross-section is being reduced is formed. Supplementary or alternatively, the reduction of the cross-section of the hollow body can be associated with the formation of a desired outer profile of the hollow body and / or the formation of a desired inner profile of the hollow body.

[0021] According to the invention, the mandrel and the hollow body can be kinematically linked in various ways to apply a tensile load to the hollow body in the direction of the axial mandrel movement.

[0022] According to claim 8, according to the invention, the mandrel applies a tensile load to the hollow body wall based on a form connection that occurs between the mandrel and the hollow body wall. To form the form connection, for example, the hollow body wall can have a protrusion that projects into the hollow body interior, and the mandrel is supported at an end located in the direction of the axial mandrel movement on this protrusion.

[0023] According to claim 9, in a further configuration of the invention, a friction connection is formed between the mandrel and the hollow body wall of the hollow body to be shaped. Preferably, according to claim 10, for this purpose, it is assumed that a shaping die arranged on the outer surface of the hollow body loads the hollow body wall radially with respect to the mandrel in the direction of the hollow body axis. Thus, the formation of the friction connection between the hollow body wall and the mandrel is carried out at the start of the shaping process.

[0024] According to the invention, it is also conceivable to connect the hollow body wall to the mandrel that performs the axial mandrel movement by means of a form connection and by means of a friction connection.

[0025] The invention will be explained in detail below based on exemplary schematic diagrams.

Brief Description of the Drawings

[0026] [Figure 1]This is a very schematic diagram showing a device used to reduce the cross-sectional area of ​​a pipe before the deformation processing process begins. [Figure 2] This diagram shows the apparatus shown in Figure 1 during the deformation processing step. [Modes for carrying out the invention]

[0027] According to Figures 1 and 2, the apparatus 1 is used to reduce the cross-section of a tubular hollow body in the form of a cylindrical tube 2. The tube 2 has a tube wall 3 made of a plastically deformable material as the hollow body wall, and a tube axis 4 extending in the longitudinal direction of the tube 2 as the hollow body axis.

[0028] From pipe 2, steering shafts for automobiles are manufactured through multiple manufacturing steps.

[0029] Within the scope of the manufacturing process, the cross-section of pipe 2, and more specifically the thickness of the pipe wall 3, is reduced using the apparatus 1.

[0030] For this purpose, apparatus 1 is incorporated into conventional structural axial forming machines, such as the axial forming machine offered by FELSS Systems GmbH (75203 Koenigsbach-Stein, Germany) under the product name "Aximus".

[0031] The axial forming machine has a tool holder for the deformation die 5 that is movable along the tube axis 4, and a mandrel holder for fixing the end of the mandrel 6 opposite to the deformation die 5, which is also movable along the tube axis 4. The tool holder for the deformation die 5 and the mandrel holder are not shown in the drawings for simplification.

[0032] The deformation die 5 has a die opening 7 ("calibration section") formed to reduce the cross-sectional area of ​​the pipe 2, and the opening cross-section of the die opening is smaller than the cross-sectional area of ​​the pipe 2 in the starting state shown in Figure 1.

[0033] In the illustrated example, the die opening 7 has a smooth wall. Alternatively, the die opening 7 may have a shaping element on its circumferential surface, such as a shaping tooth row or a profile forming element.

[0034] The deformation processing drive unit 8, shown in a highly schematic manner in Figure 1, includes a mandrel drive unit 9 and a die drive unit 10. A numerical drive control device 11 controls both the mandrel drive unit 9 and the die drive unit 10.

[0035] The pipe 2 to be deformed is supported at one end by a stationary axial support 12 along the pipe axis 4 in an axial forming machine.

[0036] To reduce the cross-sectional area of ​​pipe 2, the mandrel 6 is moved along the pipe axis 4 in the direction of arrow 13 by axial mandrel motion using the mandrel drive device 9, and the deformation die 5 is moved along the pipe axis 4 in the direction of arrow 14 by axial die motion using the die drive device 10.

[0037] Figure 1 shows the state of apparatus 1 immediately before the start of deformation processing to reduce the cross-sectional area of ​​pipe 2. The mandrel 6 is moved at high speed to various positions along the pipe axis 4 using the mandrel drive unit 9, and the deformation die 5 is moved at high speed using the die drive unit 10.

[0038] At this point, the feed rates of the deformation die 5 and mandrel 6 are relatively high, but as soon as the die opening 7 of the deformation die 5 reaches the end of the pipe 2 located on the side of the deformation die 5, the feed rates are significantly reduced based on the corresponding control of the mandrel drive unit 9 and die drive unit 10 by the drive control device 11.

[0039] The speed reduction of the deformation die 5 and mandrel 6 can be achieved by both position control and force control.

[0040] In the illustrated embodiment, for the deformation of pipe 2, the drive control device 11 is used to adjust the speed of the axial mandrel motion in the direction of arrow 13 to 15 mm / second, and the speed of the axial die motion of the deformation die 5 in the direction of arrow 14 to 60 mm / second. The axial mandrel motion and the axial die motion are superimposed on each other by the drive control device 11.

[0041] When the free end of pipe 2 enters the die opening 7, the pipe wall 3 is pressed against the mandrel 6 in that region. This creates a frictional connection between the pipe wall 3 and the mandrel 6.

[0042] Simultaneously, the pipe wall 3 is compressed by the deformation die 5 on the side located in the direction of arrow 14, based on the axial die motion in the direction of arrow 14, which is superimposed on the axial mandrel motion, thereby exceeding the yield point of the material of the pipe wall 3. The axial support 12 that supports the pipe 2 being loaded by the deformation die 5 is stationary along the pipe axis 4 while the pipe 2 is being loaded by the deformation die 5.

[0043] Due to the frictional connection between the pipe wall 3 and the mandrel 6, the pipe wall 3, which is loaded on its outer surface by the deformation die 5, is subjected to tensile load by the mandrel 6 in the direction of arrow 13 on the side of the deformation die 5 located in the direction 13 of the axial mandrel motion. Therefore, the mandrel 6, driven by the mandrel drive unit 9, actively pulls the pipe wall 3 through the die opening 7 in the direction of arrow 13, causing the pipe 2 to stretch and the thickness of the pipe wall 3 to decrease simultaneously.

[0044] Figure 2 shows the state of apparatus 1 during the deformation processing.

[0045] The mandrel 6 applies a tensile load to the pipe wall 3 on the side opposite to the deformation die 5 in the direction of axial mandrel motion 13. The deformation die 5 applies a compressive load to the pipe wall 3. The forces applied to the pipe wall 3 by the deformation die 5 and the mandrel 6 are shown by arrows 15 and 16 in Figure 2.

[0046] By appropriately adjusting the axial mandrel motion in the direction of arrow 13 and the axial die motion in the direction of arrow 14, that is, by appropriately controlling the mandrel drive unit 9 and the die drive unit 10, a reduction in the thickness of the pipe wall 3 occurs without crushing of the pipe 2 on the side of the deformation die 5 located in the direction of arrow 14. Therefore, in the case of apparatus 1, there is no need to provide additional reinforcing material on the outer surface of the pipe 2 to avoid crushing of the pipe 2.

[0047] In Figure 2, the distance the mandrel 6 slides in the axial direction of mandrel motion 13 relative to the position of the mandrel in Figure 1 is X D This is shown by [figure 2]. Accordingly, in Figure 2, the length of the travel distance of the deformation die 5, starting from the state in Figure 1, is X M This is shown by [the source].

[0048] In the illustrated embodiment, by appropriately controlling the mandrel drive unit 9 and the die drive unit 10, the mandrel drive unit 9 and the die drive unit 10 can be stopped simultaneously when the desired deformation length of the pipe 2 is reached.

[0049] The simultaneous axial mandrel motion and the axial die motion in the opposite direction allow for a high deformation processing speed using apparatus 1. Despite the high deformation processing speed, high-quality processing results are obtained in pipe 2.

Claims

1. A method for reducing the cross-sectional area of ​​a tubular hollow body (2) by deformation processing of the hollow body (2), wherein the hollow body has a hollow body wall (3) made of a plastically deformable material and a hollow body axis (4) extending in the longitudinal direction of the hollow body (2), A deformation die (5) is placed on the outer surface of the hollow body (2), and the deformation die has a die opening (7) formed to receive the hollow body (2), which has an opening cross-section smaller than the hollow body cross-section of the hollow body (2) in the starting state. A mandrel (6) is placed inside the hollow body (2), The deformation die (5) positioned on the outer surface of the hollow body (2) is moved relative to the hollow body (2) in the direction of the axial die motion (14) along the axis (4) of the hollow body, using a die drive device (10), while reducing the cross-sectional area of ​​the hollow body (2). The mandrel (6) positioned inside the hollow body (2) is moved along the hollow body axis (4) and through the die opening (7) using a mandrel drive device (9) provided in addition to the die drive device (10), in an axial mandrel motion opposite to the axial die motion of the deformation die (5) positioned on the outer surface of the hollow body (2). In a method in which a tensile load is applied to the hollow body wall (3) using the mandrel (6) based on the axial mandrel motion in the direction of the axial mandrel motion (13), thereby pulling the hollow body wall (3) through the die opening (7) in the direction of the axial mandrel motion (13) with respect to the deformation die (5) positioned on the outer surface of the hollow body (2), The hollow body (2) is supported in the direction of the axial die motion by an axial support (12) that is fixed in position along the hollow body axis (4) during the axial die motion of the deformation die (5) which is located outside the hollow body (2). The mandrel drive unit (9) and the die drive unit (10) are controlled so that the axial movement of the mandrel and the axial movement of the deformation die (5) arranged on the outer surface of the hollow body (2) are superimposed on each other. A method characterized in that the mandrel (6) is supported on the hollow body wall (3) by a frictional connection that is effective in the direction of the axial mandrel motion (13), thereby applying a tensile load to the hollow body wall (3) in the direction of the axial mandrel motion (13) using the mandrel (6) based on the axial mandrel motion.

2. The method according to claim 1, characterized in that the ratio of the amount of axial mandrel motion to the amount of axial die motion of the deformation die (5) arranged on the outer surface of the hollow body (2), and the ratio of the speed of axial mandrel motion to the speed of axial die motion of the deformation die (5) arranged on the outer surface of the hollow body (2), are selected such that when the speed of axial mandrel motion and the speed of axial die motion are different, the axial mandrel motion and the axial die motion end simultaneously when the deformation length is reached.

3. The deformation die (5) is moved by positioning motion using the die drive device (10) from a position away from the hollow body (2) to be deformed to a position where the deformation die (5) is positioned on the outer surface of the hollow body (2), The method according to claim 1 or 2, wherein, using the drive control device (11) of the deformation processing drive device (8), the die drive device (10) and the mandrel drive device (9) are controlled so that, after the mandrel drive device (9) starts the axial mandrel motion, the deformation processing die (5) is positioned on the outer surface of the hollow body (2) based on the positioning motion of the deformation processing die (5).

4. The method according to claim 1 or 2, wherein the deformation die (5) positioned on the outer surface of the hollow body (2) loads the hollow body wall (3) against the mandrel (6) in the radial direction of the hollow body axis (4), so that the mandrel (6) is supported by the hollow body wall (3) by a frictional connection that is effective in the direction of the axial mandrel motion (13).

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