System and method for necking out an opening of a hollow body

Abstract

The present disclosure relates to a system (21) for necking out an opening (5) of a hollow body (7) by means of a machine (63) suitable for turning, milling and / or drilling workpieces about a rotary axis (D), wherein the system (21) comprises: - a spindle nut (23) that can be clamped into a chuck (53) of the machine (63) and which has an internal thread, - a spindle rod (27) having a threaded section with an external thread (25) that can be screwed into the internal thread of the spindle nut (23), - a spacer (29) with a spindle rod guide (28) and a rotatably mounted spindle nut stop (30), - a hollow body holder (31) that can be positioned in a desired position relative to the chuck (53) of the machine (63) for fixing the hollow body (7) by means of the hollow body holder (31), wherein the hollow body holder (31) has two spacer stops (33), and - a neck cone (15, 37) which can be detachably and tensilely connected to a free end (39) of the spindle rod (27), wherein the spacer (29) has two hollow body support stops (35) which are aligned towards the spacer stops (33) of the hollow body support (31) in order to each abut against one of the spacer stops (33) of the hollow body support (31).

Description

[0001] The present disclosure relates to a system and method for necking out an opening in a hollow body. The hollow bodies are mainly metallic pipes. However, the present disclosure can also be applied to other hollow bodies, for example, tanks or containers, where the material of the hollow body is plastically deformable.

[0002] Flaring is a mechanical process for creating branches on hollow bodies, most commonly pipe branches. Its main applications are in plant and pipeline construction, as well as mechanical engineering. Hollow bodies with flared openings are found particularly in the food industry, pharmaceutical industry, biotechnology, water and wastewater treatment plants, ventilation systems, shipbuilding, automotive manufacturing, and many other sectors.

[0003] To add a branch to a pipe, a T-fitting is typically used. However, a disadvantage of using a T-fitting is that it involves three connection points. Each added connection point increases the likelihood of leaks and recalls, and worsens flow and durability. Furthermore, T-fittings must be kept in stock and imply that the pipe has to be cut, resulting in material waste.

[0004] Necking is advantageous compared to using a T-piece insert because it creates only one connection point. Necking eliminates the need for T-pieces and avoids cutting the hollow body; instead, it simply bores out with minimal material waste. The diameter of the neck opening can be customized to meet specific requirements.

[0005] In principle, it is known to use a necking cone to neck out a hollow body. For example, DE 23 18 063 C3 describes a method for producing necks on hollow metal bodies, in which a drawing tool is pulled through an opening in the hollow body by means of a transport device.

[0006] The system and method for necking known from DE 23 18 063 C3 has several disadvantages. Firstly, the drawing body must be heated before necking begins. Secondly, a hydraulic transport device is required to pull the drawing body out of the hollow body. This hydraulic transport device makes the known necking system expensive and complex. Furthermore, the hydraulic transport device is not versatile and is limited to the specific application of necking.

[0007] It is therefore an objective of the present disclosure to provide a system and method for necking out an opening in a hollow body that is significantly simpler and cheaper.

[0008] This problem is solved by a system according to claim 1 or a method according to claim 13. The basic idea of ​​the present invention is to use a commercially available turning, milling, and / or drilling machine, normally used for machining workpieces, for the purpose of necking out a cavity. According to a first aspect of the present disclosure, a system for necking out an opening of a hollow body using a machine suitable for turning, milling, and / or drilling workpieces about a rotary axis is thus provided, wherein the system comprises: - a spindle nut that can be clamped into a chuck of the machine and has an internal thread, - a spindle rod having a threaded section with an external thread that can be screwed into the internal thread of the spindle nut, wherein preferably the spindle rod screwed into the spindle nut extends coaxially to the axis of rotation of the machine when the spindle nut is clamped in the machine's chuck, - a spacer with a spindle rod guide and a rotatably mounted spindle nut stop, - a hollow body holder that can be positioned in a desired position relative to the chuck of the machine for fixing the hollow body by means of the hollow body holder, wherein the hollow body holder has two spacer stops, and - a necking cone which can be detachably and tensilely connected to a free end of the spindle rod, preferably when it is temporarily held on the inside of the hollow body aligned with the opening of the hollow body to be necked out, and the spindle rod is inserted into the hollow body through the opening of the hollow body, wherein the spacer has two hollow body support stops which are aligned towards the spacer stops of the hollow body support in order to each abut against one of the spacer stops of the hollow body support, preferably when the spindle nut is rotated on the spindle rod by means of the axis of rotation, so that the spindle rod moves axially towards the chuck of the machine and the hollow body is held at a distance from the spindle nut, while the necking cone is pulled out of the hollow body by the spindle rod through the opening to be necked out.

[0009] The machine could be a conventional stationary lathe with a horizontal axis of rotation. Alternatively, the machine's axis of rotation could be vertical. For example, the machine could be a stationary drilling and / or milling machine with a horizontal or vertical axis of rotation. It is also conceivable that the machine is not stationary but mobile, for example, handheld, and that the axis of rotation can be positioned and / or aligned as desired.

[0010] Since such a machine is not typically designed to withstand high axial tensile forces, the inventive system for necking ensures that virtually no axial tensile forces act on the machine's chuck. Because the spindle nut rests against the spindle nut stop and the spacer stops rest against the hollow body support stops, the inventive system absorbs all axial tensile forces. The machine's chuck merely rotates the spindle nut, causing the spindle rod to move axially towards the chuck.

[0011] The system can feature a variety of different-sized and / or shaped neck cones, from which one can be selected as needed to achieve the desired neck shape. The system can also feature a variety of different-sized and / or shaped hollow body holders, from which a suitable one can be selected to secure the hollow body. For hollow bodies in the form of tubes with varying standardized diameters, hollow body holders or hollow body holder inserts with corresponding inner diameters are available.

[0012] Optionally, the spacer can be U-shaped with a transverse element on which the spindle rod guide and the rotatably mounted spindle nut stop are located, and two leg elements extending from the transverse element to the spacer stops of the hollow body holder, with one free end of each leg element forming one of the hollow body holder stops. Since the spacer must withstand high tensile forces, it is preferably dimensionally stable and made of a steel structure. For example, the transverse element can essentially consist of a square steel tube with a rectangular cross-section. Preferably, the transverse element is long enough to allow the system to accommodate the largest possible necking, but not so long that it deflects under the tensile load during necking. The transverse element preferably has a length of 15 to 50 cm.The two leg elements are preferably identical in design and arranged symmetrically with respect to the axis of rotation. The distance between the leg elements and the axis of rotation is at least large enough to allow the necking cone to fit between them. The leg elements preferably have a width transverse to the axis of rotation that extends to the respective end of the transverse element. This has the advantage that the spacer is particularly rigid and that the hollow body support stops can extend across the entire width of the leg elements. This provides a degree of flexibility to adjust the distance between the hollow body supports to the size of the opening to be necked out.

[0013] Optionally, the leg elements can extend from the transverse element to the respective hollow body support stop over an axial length that is longer than the axial length of the necking cone. This ensures that the spacer provides sufficient clearance to completely withdraw the necking cone from the opening of the hollow body to be necked. However, the leg elements can be wider transversely to the axis of rotation than they are long along the axis of rotation.

[0014] Optionally, the spacer can be designed to be essentially symmetrical with respect to the axis of rotation. This is particularly advantageous to prevent lateral forces and ensure that both hollow body supports each absorb half of the tensile force.

[0015] Optionally, the hollow body holder can comprise a base element and two clamps, wherein the clamps can each be positioned relative to the base element transversely to the axis of rotation and fixed to the base element, and which grip the hollow body, with the distance between the clamps being adjustable so that the opening of the hollow body to be cut fits between the clamps. The base element is preferably designed so that it can be mounted on a work slide of the machine.

[0016] Optionally, the neck cone can have an internal thread into which the free end of the spindle rod can be screwed. Preferably, the threaded section of the spindle rod with the external thread can extend over the entire length of the spindle rod. The neck cone can be secured to the spindle rod by means of one or more locknuts screwed against it.

[0017] Optionally, the necking cone can have a first truncated cone surface and a second truncated cone surface, wherein the first truncated cone surface has a smaller base radius than the second truncated cone surface, wherein the first truncated cone surface is located closer to the spindle nut than the second truncated cone surface, and wherein the first truncated cone surface has a larger opening angle than the second truncated cone surface. The first truncated cone surface serves to initially widen the opening of the hollow body to be necked. The second truncated cone surface then serves for the subsequent main part of the necking process, in which the opening of the hollow body to be necked is widened. If the hollow body is a tube, the difficulty of the necking depends on the diameter of the necking relative to the tube diameter.In principle, the present invention makes it possible to create necks with a diameter that is equal to or almost equal to the pipe diameter. To achieve this, for example, necking cones of different sizes and / or shapes can be used sequentially to create the final neck in several stages. This is because the opening to be necked may need to have a certain minimum size to allow for the positioning and alignment of a correspondingly large necking cone within the hollow body. By using a necking cone with two truncated conical surfaces, it is possible, for certain ratios of neck diameter to pipe diameter, to perform the necking with only one necking cone. A second necking stage with a second necking cone can then be eliminated.

[0018] Optionally, the first truncated cone surface can have a significantly smaller height in the direction of the axis of rotation than the second truncated cone surface. This is advantageous because the flared cone is preferably designed to be as short as possible and as long as necessary in the axial direction.

[0019] Alternatively or in addition to two truncated conical surfaces, the opening angle of the truncated conical surface can change stepwise and / or continuously along the length of the neck cone. Preferably, the opening angle increases stepwise and / or continuously towards the spindle rod.

[0020] Optionally, the necking cone can have a narrow axial end facing the spindle nut and a wide axial end facing away from the spindle nut. The necking cone has at least one recess at the wide end into which a retaining element can engage to temporarily hold the necking cone aligned with the opening of the hollow body to be necked. The retaining element can, for example, be a rod to which the wide end of the necking cone can be laterally attached. The rod can then be inserted lengthwise into the hollow body with the necking cone until the narrow end of the necking cone is positioned at the opening of the hollow body to be necked.

[0021] Optionally, the neck cone can have a continuous axial bore with an internal thread, whereby the free end of the spindle rod can be screwed into the internal thread from the narrow end of the neck cone, and the retaining element can be screwed into the internal thread from the wide end of the neck cone. A quarter turn of the thread may be sufficient for temporarily fixing the neck cone to the retaining element. Once the free end of the spindle rod is screwed into the narrow end of the neck cone, the neck cone can be detached from the retaining element, and the retaining element can be removed from the hollow body.

[0022] Optionally, the system includes at least one lock nut to secure the necking cone to the spindle rod. Rotation of the spindle rod around its axis of rotation is undesirable. Although the spindle nut, turned by the machine, exerts a certain torque on the spindle rod due to thread friction, the higher frictional force of the necking cone in the opening of the hollow body to be necked prevents the spindle rod from rotating unintentionally with the spindle nut.

[0023] According to a further aspect of the present invention, a method for necking out an opening of a hollow body is provided by means of a machine suitable for turning, milling and / or drilling workpieces about a rotary axis, wherein the method comprises: - Positioning a hollow body holder in a desired position relative to a machine chuck, wherein two spacer stops of the hollow body holder are aligned towards the machine chuck, - Fixing the hollow body using the hollow body holder, - Holding and aligning a necking cone on the inside of the hollow body with the opening of the hollow body to be necked out, - Detachable and tensile-resistant connection of the necking cone, which is held and aligned on the inside of the hollow body against the opening to be necked in the hollow body, to a free end of the spindle rod, - Mounting a spacer with a spindle rod guide and a rotatably mounted spindle nut stop onto the spindle rod, so that the spindle rod extends through the spindle rod guide and the spindle nut stop abuts a spindle nut screwed onto the spindle rod, - Clamping the spindle nut into the machine's chuck so that the spindle rod extends coaxially to the machine's axis of rotation, and - Rotating the spindle nut on the spindle rod by means of the machine, so that the spindle rod moves axially towards the chuck of the machine and the hollow body is held at a distance from the spindle nut by means of the spacer, while the necking cone is pulled out of the opening to be necked out of the hollow body by the spindle rod, with two hollow body support stops of the spacer each striking against one of the spacer stops of the hollow body support.

[0024] It should be noted that the individual process steps can be carried out in different sequences and / or simultaneously. The machine suitable for turning, milling, and / or drilling workpieces around a rotary axis can, for example, be a conventional stationary or mobile lathe, milling machine, and / or drilling machine. The rotary axis can extend horizontally, as with a conventional stationary lathe, or vertically, as with a stationary drilling machine. It is also conceivable that the machine is a handheld milling or drilling machine, allowing the rotary axis to be oriented as desired.

[0025] Optionally, the procedure may also include the following steps: - Machining the opening in the hollow body fixed in the hollow body holder using a drilling and / or milling tool clamped in the machine's chuck, and - Mounting the drilling and / or milling tool from the machine's chuck when the opening in the hollow body has been machined.

[0026] This has the advantage that the machine can be used for both drilling and milling the hollow body as well as for necking it out. No separate machines are required for this, and the hollow body does not need to be removed from the hollow body holder. Furthermore, the process does not subject the machine to harmful axial tensile forces.

[0027] Optionally, the method can further include a step of lubricating the necking cone with a lubricant. Such a lubricant has the advantage of protecting the inner wall of the hollow body and requiring lower torques from the machine during necking. Furthermore, the tensile force acting on the system according to the invention is reduced by a lubricant.

[0028] Optionally, the procedure could also include the following steps: - Loosening the spindle nut and removing the neck cone, spindle rod and spacer when the neck cone is completely pulled out of the necked opening on the hollow body, and - Machining the axial end face of the hollowed-out opening of the hollow body using a drilling and / or milling tool clamped in the chuck of the machine.

[0029] This is particularly advantageous for using the machine for post-processing the axial end face of the hollow body's cut-out opening. This makes the process especially efficient, and the hollow body can remain fixed in the hollow body holder from the drilling of the opening to the machining of the axial end face of the cut-out opening.

[0030] A pipe section can then be easily welded to the flat, axial end face of the hollow body to form a pipe branch. The simple, circular weld can be performed by a welding robot and is so straightforward that no X-ray inspection of the weld is required. More complex weld configurations, on the other hand, often need to be welded manually by well-trained and experienced personnel, in which case X-ray inspection of the weld is necessary.

[0031] The invention will be explained in more detail below with reference to the accompanying figures. These show: Fig. 1a schematically a T-piece known from the prior art; Fig. 1b, c the principle of connecting a pipe with a hollowed-out opening, once in perspective view and once in longitudinal section; Fig. 2a-e schematically show the basic work steps involved in chamfering; Fig. 3 a perspective view of an embodiment of the system according to the invention; Fig. 4 a schematic longitudinal section view of an embodiment of the system according to the invention during the insertion of the neck cone; Fig. 5 a schematic longitudinal section view of an embodiment of the system according to the invention, when the neck cone is positioned and detachably and tensilely connected to the spindle rod; Fig. 6 a schematic longitudinal section view of an embodiment of the system according to the invention during the extraction of the neck cone from the hollow body; Fig. 7 a schematic longitudinal section view of an embodiment of the system according to the invention, after the necking cone has been completely withdrawn from the opening of the hollow body to be necked out; Fig. 8 a perspective view of the drilling of the opening to be cut into the hollow body using a lathe; Fig. 9 a perspective view of drilling the opening to be cut out of the hollow body with a metal drill bit clamped in a lathe; Fig. 10 a perspective view of milling an elliptical shape into the opening to be cut into the hollow body; Fig. 11 a perspective view of the milling of a flower-shaped neck opening of the hollow body; Fig. 12 a perspective view of the insertion of a neck cone into the hollow body by means of a holding device; Fig. 13 a perspective view of an embodiment of the system according to the invention shortly before the exhalation process; Fig. 14 a perspective view of an embodiment of the system according to the invention shortly after the exhalation process; Fig. 15 a perspective view of the plan machining of an axial end face of the hollowed-out opening with a milling head; and Fig. 16 a perspective view of the plan machining of an axial end face of the hollow body's hollowed-out opening using a spindle tool.

[0032] Fig. Figure 1a shows a conventional T-piece 1 known from the prior art. It features a relatively complex weld 3, which can only be manufactured economically in industrial series production. If the weld 3 has to be performed manually, experienced and well-trained personnel are required. Furthermore, depending on the application, the weld 3 would have to undergo X-ray inspection to ensure sufficient weld quality. When inserting the T-piece 1 into a pipe, the pipe has to be cut open and the T-piece 1 inserted. Together with the pipe branch, this creates three new connection points, each implying a risk of leaks.

[0033] The Fig. 1 b and Fig. Figure 1c, in contrast, shows the advantage of a flared lateral opening 5 on a tubular hollow body 7. For this purpose, the tubular hollow body 7 is laterally bored, and the material of the tubular hollow body 7 is plastically bent at the lateral opening 5 such that a flat axial end face 8 is created to which a pipe branch 9 can be easily welded. As a result, the pipe branch 9 has only one connection point with a simple circular weld 11, which can be performed by a welding robot and does not require X-ray inspection. Flaring thus offers considerable advantages, particularly in applications with high quality requirements, compared to a T-piece 1 known from the prior art according to [reference to prior art]. Fig. 1a.

[0034] The basic procedure for necking according to the invention using a necking cone is described in the Fig. 2a-e shown. Fig. Figure 2a shows only a tubular hollow body 7 made of plastically deformable material, for example, steel. It should be noted that the figures each have a right-handed Cartesian coordinate system, in which the x-axis runs along the longitudinal direction of the hollow body, and the y-axis and the z-axis run perpendicular to the longitudinal direction of the hollow body, with the z-axis extending in the direction in which the opening 5 of the hollow body 7 is to be cut. Fig. Figure 2b shows how the opening 5 is drilled laterally in the negative Z-direction into the hollow body 7. The drilling can be carried out with a drilling and / or milling tool 13. Fig. Figure 2c shows in the zy plane that an elliptical shape is formed for the opening 5 to be cut out using the drilling or milling tool 13. This is useful for tubular hollow bodies 7 in order to have sufficient material around the opening 5 for plastic deformation. Fig. Figure 2d shows how a necking cone 15 is inserted from an open end of the tubular hollow body 7 into the hollow body 7 and positioned on the inside against the opening 5. The necking cone 15 is oriented such that its longitudinal axis runs in the z-direction, with a narrow axial end 17 of the necking cone 15 resting on the inside against the opening 5 to be necked. Fig. Figure 2e then shows the actual necking process, in which the necking cone 15 is pulled out of the opening 5 to be necked from the tubular hollow body 7 in the z-direction, whereby the opening 5 to be necked is plastically deformed and forms a necked collar. Since the necking cone widens radially towards a broad axial end 19, the opening 5 of the hollow body 7 to be necked widens as the necking cone 17 is pulled out. Following the necking process, an axial end face 8 of the necked opening 5 can be machined flat (in Fig. 2a-e not shown).

[0035] Fig. Figure 3 shows a perspective view of an embodiment of a system 21 according to the invention for necking out an opening 5 of a hollow body 7 using a machine suitable for turning, milling and / or drilling workpieces about a rotary axis D. The machine is in Fig. Figure 3 is not shown, but only the system 21 according to the invention. The system 21 has a spindle nut 23 that can be clamped into a chuck (not shown) of the machine. The spindle nut 23 is screwed onto an external thread 25 of a spindle rod 27 via an internal thread. The external thread 25 of the spindle rod 27 extends over at least a threaded section of the spindle rod 27, which in the illustrated embodiment extends over the entire length of the spindle rod 27. The system 21 also has a spacer 29, which has a spindle rod passage 28 and a rotatably mounted spindle nut stop 30. The spindle rod 27 passes through the spindle rod passage 28 in the z-direction through the spacer 29. The system 21 also has a hollow body holder 31, which can be positioned in a desired position relative to the chuck of the machine.The hollow body holder 31 serves to fix a hollow body 7 which is in . Fig. Although not shown, the hollow body holder 3 extends tubularly in the x-direction when held by the hollow body holder 31. The hollow body holder 31 has two spacer stops 33 oriented towards the spacer 29. The spacer 29 correspondingly has two hollow body holder stops 35 oriented in the negative z-direction towards the spacer stops 33 of the hollow body holder 31, each abutting one of the spacer stops 33 of the hollow body holder 31. Finally, the system 21 has a neck cone 37 that can be detachably and tensilely connected to a free end 39 of the spindle rod 27. In the Fig. In the embodiment shown in Figure 3, the neck cone 37 has an internal thread into which the free end 39 of the spindle rod 27 is screwed. The neck cone 37 is secured to the spindle rod 27 by two locknuts 41.

[0036] When the spindle nut 23 is clamped in a chuck of the machine, the spindle rod 27 extends along the axis of rotation D of the machine in the z-direction. As the spindle nut 23 is rotated by the machine, the spindle rod 27 is moved axially in the z-direction. The spindle nut 23 then abuts the spindle nut stop 30 of the spacer 29. The spindle nut stop 30 is rotatably mounted relative to a transverse element 45 of the spacer 29 via an axial bearing. Thus, when the spindle nut 23 is rotated by the machine, the spindle rod 27 pulls the neck cone 37 out of the hollow body 7 clamped in the hollow body holder 31 in the z-direction without the spindle rod 27 itself rotating. The spacer 29, which with its two hollow body support stops 35 abuts the spacer stops 33 of the hollow body support 31, together with the hollow body support 31, keeps the hollow body 7 at a distance from the spindle nut 23.

[0037] The spacer 29 is U-shaped, with the transverse element 45 extending parallel to the hollow body 7 in the x-direction, perpendicular to the axis of rotation D running in the z-direction. The spindle rod guide 28, extending in the z-direction, and the spindle nut stop 30, rotatably mounted by means of the axial bearing 43, are located centrally on the transverse element 45. Leg elements 47 of the spacer 29 extend from the transverse element 45 to the spacer stops 33 of the hollow body holder 31 in the negative z-direction. A free end of each leg element 47 forms one of the hollow body holder stops 35 of the spacer 29. This makes the spacer 29 symmetrical with respect to the axis of rotation D running in the z-direction. The leg elements 47 each extend from the transverse element 45 to the respective hollow body support stop 35 in the negative z-direction over a length that is longer than the neck cone 37 in the z-direction.This allows the neck cone 37 to be completely pulled out of the hollow body 7 and to fit between the leg elements 47.

[0038] The hollow body holder 31 comprises a base element 49 and two clamps 51, wherein the clamps 51 can each be positioned relative to the base element 49 transversely to the axis of rotation D in the x-direction relative to each other. The clamps 51 can be fixed to the base element 49 and can grip the hollow body 7 in a fixed manner. A distance in the x-direction between the clamps 51 is adjustable such that the opening 5 of the hollow body 7 to be cut out fits between the clamps 51. The base element 49 is preferably mountable on a work slide of the machine. The clamps 51 each have one of the spacer stops 33 of the hollow body holder 31 where their outer surface faces the hollow body holder stops 35 of the spacer 29 in the z-direction.

[0039] The Fig. Figures 4 to 7 illustrate, in longitudinal sections in the xz plane, an embodiment of an extrusion process according to the invention, in which the system 21 according to the invention is used. Fig. In Figure 4, the hollow body holder 31 is already positioned in a desired position relative to a machine chuck 53, such that the two spacer stops 33 of the hollow body holder 31 are aligned in the z-direction towards the machine chuck 53. Furthermore, a tubular hollow body 7 is already fixed by means of the hollow body holder 31. For this purpose, the two clamps 51 of the hollow body holder 31 grip the tubular hollow body 7 and are fixed to the base element 49 at a distance from each other in the x-direction. Depending on the length and diameter of the hollow body 7, a holding device 55 is useful to position the necking cone 37 inside the hollow body 7, aligned with the opening 5 of the hollow body 7 to be necked out. If the hollow body 7 is not too long and wide, the necking cone 37 can simply be held by hand inside the hollow body 7, aligned with the opening 5 of the hollow body 7 to be necked out.However, if the hollow body 7 is too long or too narrow for this, as in . Fig. As shown in Figure 4, a holding element 55 in the form of a rod is used for this purpose. The holding element 55 can, for example, be a flat steel bar with a relatively short thread 57 laterally at one free end, which is screwed into a wide axial end 19 of the necking cone 37. A quarter turn may be sufficient to temporarily attach the necking cone 37 to the holding element 55. The holding element 55 can then be manually inserted and positioned so that the necking cone 37, with its longitudinal axis aligned in the z-direction, rests against the inside of the opening 5 of the hollow body 7 to be necked out.

[0040] In Fig. Figure 5 shows how the free end 39 of the spindle rod 27 is screwed into the narrow axial end 17 of the necking cone to detachably and tensilely connect the necking cone 37 to the spindle rod 27. The necking cone 37 is secured to the spindle rod 27 by the lock nut 41. The retaining element 55 is then no longer needed, so that the necking cone 37 can be unscrewed from the short thread 57 of the retaining element 55 using the spindle rod 27, and the retaining element 55 can be removed.

[0041] The neck cone 37 has in the Fig. In the embodiment shown in Figures 4 to 7, a first truncated cone surface 59 and a second truncated cone surface 61 are depicted, wherein the first truncated cone surface 59 has a smaller base radius than the second truncated cone surface 61. The first truncated cone surface 59 is located closer to the spindle nut 23 than the second truncated cone surface 61. The first truncated cone surface 59 has a larger opening angle than the second truncated cone surface 61. The first truncated cone surface 59 serves to initially widen the opening 5 of the hollow body 7 to be necked out, and the second truncated cone surface 61 serves for the main part of the necking process. The first truncated cone surface 59 has a cone height that is many times smaller in the z-direction, i.e., in the direction of the axis of rotation D, than the second truncated cone surface 61.The second truncated conical surface 61 has a top surface radius equal to the base surface radius of the first truncated conical surface 59. This shape of the necked cone 37 has proven to be particularly advantageous, especially for necked openings 5 ​​whose diameter is to be 80% or more of the diameter of the tubular hollow body 7.

[0042] In Fig. Figure 6 shows the actual necking process, in which the machine's chuck 53 is rotated so that the spindle nut 23 is rotated about the axis of rotation D extending in the z-direction. The spindle nut stop 30 of the spacer 29, which is rotatably mounted by means of the axial bearing 43, rests against the spindle nut 23. The hollow body support stops 35 of the spacer 29 each abut the corresponding spacer stop 33 of the hollow body support 31, so that the hollow body 7 is held at a defined distance from the spindle nut 23. The spindle rod 27 does not rotate with the spindle nut 23, because the necking cone 37 is in frictional engagement with the material of the hollow body 7 to be plastically deformed. The spindle rod 27 is moved axially in the z-direction while the spindle nut 23 is stretched, thus pulling the necking cone 37 out of the opening 5 of the hollow body 7 to be necked out.In this process, the material of the hollow body 7 is plastically deformed around the opening 5 of the hollow body 7 to be cut out, so that a cut-out opening 5 is formed. In . Fig. 7 The neck cone 37 is completely pulled out of the necked opening 5 of the hollow body 7 and fits completely between the leg elements 47 of the U-shaped spacer 29 in both length and width. The machine is stopped before the lock nut 41 strikes the transverse element 45 of the spacer 49.

[0043] Fig. Figure 8 shows in a perspective view that the machine, here in the form of a conventional lathe 63, can first be used to drill a lateral opening 5 into a tubular hollow body 7. For this purpose, as shown in Fig. Figure 8 shows a twist drill 64 clamped in a chuck 53 of the lathe 63. The hollow body holder 31 is used here not only for the actual necking process, but also for clamping the tubular hollow body 7 when machining the opening 5 of the hollow body 7 to be necked. The clamps 51 of the hollow body holder 31 have inserts 65 to allow clamping of a tubular hollow body 7 with a smaller diameter. The base element 49 of the hollow body holder 31 is mounted on a work slide 67 of the lathe 63.

[0044] In Fig. Figure 9 shows that for larger diameters of the opening 5 to be necked out, for example, a metal core drill 66 can be clamped in the chuck 53 of the lathe 63. Depending on the diameter of the hollow body 7 to be necked out, other inserts 65 and / or other clamps 51 of the hollow body holder 31 can be used accordingly.

[0045] In Fig. Figure 10 shows how a milling head 69, clamped in the chuck 53 of the lathe 63, is used to machine the opening 5 of the hollow body 7 to be cut out in an elliptical shape. The main axis of the ellipse runs in the longitudinal direction of the tubular hollow body 7, i.e., in the x-direction. Fig. Figure 11 shows that, if necessary, a flower-shaped shaping of the opening 5 to be necked out can be advantageous using a milling head 70 clamped in the chuck 53 of the lathe 63. The shape and size of the opening 5 to be necked out depends on many parameters, for example, the material of the hollow body 7, the diameter of the hollow body 7, and the target diameter of the opening 5 to be necked out.

[0046] In Fig. Figure 12 shows how the necking cone 37 is inserted into the hollow body 7 by means of the holding means 55 in order to position the necking cone 37 on the inside aligned with the opening 5 of the hollow body 7 to be necked out. Fig. Figure 13 shows the system 21 shortly before the actual necking process. The spindle nut 23 is clamped in the chuck 53 of the lathe 63 and screwed onto the spindle rod 27. The spindle rod 27 extends through the spindle rod passage 28 in the transverse element 45 of the spacer 29 in the negative z-direction along the axis of rotation D. The free end 39 of the spindle rod 27 extends through the necking opening 5 of the hollow body 7 and is screwed into the narrow axial end 17 of the necking cone 37, which extends into Fig. 13 is not visible inside the hollow body 7. The neck cone 37 can be secured to the spindle rod 27 by the lock nut 41. The free ends of the leg elements 47, which form the hollow body support stops 35, abut the spacer stops 33 on the clamps 51 of the hollow body support 31.

[0047] In Fig. Figure 14 shows how the spindle nut 23 clamped in the chuck 53 of the lathe 63 moves the spindle rod 27 in the z-direction under rotation and thus pulls the necking cone 37 out of the necking opening 5 of the hollow body 7.

[0048] In Fig. Figure 15 shows how the lathe 63 can be used after the actual necking process to machine the necked-out opening 5 of the hollow body 7 with a milling head 71 clamped in the chuck 53 of the lathe 63, in order to achieve a flat end face 8 of the necked-out opening 5. Fig. Figure 16 shows the case where the diameter of the hollowed-out opening 5 is larger than an available milling head 71, so that a spindle tool 73 is used for machining the axial end face 8 of the hollowed-out opening 5.

[0049] From drilling the opening 5 of the hollow body 7 to be necked out to machining the axial end face 8 of the necked-out opening 5 of the hollow body 7, the hollow body 7 can remain fixed in the hollow body holder 31. The lathe 63 can be used for drilling, milling, necking out, and machining the opening 5. No additional special hydraulic pulling device is required to pull the necking cone 37 out of the hollow body 7. The system 21 according to the invention prevents harmful tensile forces from acting on the lathe 63. Reference symbol list: 1 T-piece 3. Complicated weld seam 5 opening to be cut out or cut out 7 Hollow bodies 8 axial end face of the necked opening 9 pipe branch 11 simple weld 13 Drilling and / or milling tool 15 neck cones 17 narrow axial end of the neck cone 19 wide axial end of the neck cone 21 System 23 Spindle nut 25 external threads of the spindle rod 27 Spindle rod 28 Spindle rod guide 29 spacers 30 Spindle nut stop 31 Hollow body holder 33 spacer stops 35 hollow body mounting stops 37 neck cones 39 free end of the spindle rod 41 Locknut 43 axial bearings 45 Cross element of the spacer 47 leg elements of the spacer 49 Basic element of the hollow body holder 51 clamps of the hollow body holder 53 Chuck of the machine 55 retaining element 57 short thread 59 first truncated cone surface 61 second cone truncated surface 63 Lathe 64 spiral drill bits 65 deployments 66 metal drill bits 67 Working slides of the lathe 69 milling head 70 milling head 71 milling head 73 Spindle tool D axis of rotation

Claims

[1] System (21) for necking out an opening (5) of a hollow body (7) by means of a machine (63) suitable for turning, milling and / or drilling workpieces about a rotation axis (D), the system (21) comprising: - a spindle nut (23) which can be clamped into a chuck (53) of the machine (63) and which has an internal thread, - a spindle rod (27) having a threaded portion with an external thread (25) which can be screwed into the internal thread of the spindle nut (23), - a spacer (29) with a spindle rod passage (28) and a rotatably mounted spindle nut stop (30), - a hollow body holder (31) positionable in a desired position relative to the chuck (53) of the machine (63) for fixing the hollow body (7) by means of the hollow body holder (31), wherein the hollow body holder (31) has two spacer stops (33), and - a neck cone (15, 37) which can be detachably and tensile-resistantly connected to a free end (39) of the spindle rod (27), wherein the spacer (29) has two hollow body holder stops (35) which are aligned towards the spacer stops (33) of the hollow body holder (31) in order to abut against one of the spacer stops (33) of the hollow body holder (31). [2] System (21) according to claim 1, wherein the spacer (29) is U-shaped with a cross element (45) on which the spindle rod passage (28) and the rotatably mounted spindle nut stop (30) are located, and two leg elements (47) extending from the cross element (45) to the spacer stops (33) of the hollow body holder (31), wherein a free end (39) of the leg elements (47) each forms one of the hollow body holder stops (35). [3] System (21) according to claim 2, wherein the leg elements (47) each extend from the cross member (45) to the respective hollow body support stop (35) over a length which is longer than the necking cone (15, 37). [4] System (21) according to one of the preceding claims, wherein the spacer (29) is designed substantially symmetrically with respect to the axis of rotation (D). [5] System (21) according to one of the preceding claims, wherein the hollow body holder (31) has a base element (49) and two clamps (51), wherein the clamps (51) can each be positioned relative to the base element (49) transversely to the axis of rotation (D) and can be fixed to the base element (49) and encompass the hollow body (7), wherein a distance between the clamps (51) can be adjusted such that the opening (5) of the hollow body (7) to be necked out fits between the clamps (51). [6] System (21) according to one of the preceding claims, wherein the neck cone (15, 37) has an internal thread into which the free end of the spindle rod (39) can be screwed. [7] System (21) according to one of the preceding claims, wherein the necking cone (15, 37) has a first truncated cone surface (59) and a second truncated cone surface (61), wherein the first truncated cone surface (59) has a smaller base radius than the second truncated cone surface (61), wherein the first truncated cone surface (59) has a smaller distance from the spindle nut (23) than the second truncated cone surface (61), and wherein the first truncated cone surface (59) has a larger opening angle than the second truncated cone surface (61). [8] System (21) according to claim 7, wherein the first truncated cone surface (59) has a truncated cone height in the direction of the rotation axis (D) which is many times smaller than the second truncated cone surface (61). [9] System (21) according to claim 7 or 8, wherein the second truncated cone surface (61) has a top surface radius which is equal to the base surface radius of the first truncated cone surface (59). [10] System (21) according to one of the preceding claims, wherein the necking cone (15, 37) has a narrow axial end (17) facing the spindle nut (23) and a wide axial end (19) facing away from the spindle nut (23), wherein the necking cone (15, 37) has at least one recess at the wide end (19) into which a holding means (55) can engage in order to temporarily hold the necking cone (15, 37) on the inside in the hollow body (7) aligned with the opening (5) of the hollow body (7) to be necked out. [11] System (21) according to claim 10, wherein the necking cone (15, 37) has a continuous axial bore with an internal thread, wherein the free end (39) of the spindle rod (39) can be screwed into the internal thread from the narrow end (17) of the necking cone (15, 37) and the holding means (55) can be screwed into the internal thread from the wide end of the necking cone (15, 37). [12] System (21) according to one of the preceding claims, comprising at least one lock nut (41) for securing the neck cone (15, 37) on the spindle rod (27). [13] Method for necking out an opening (5) of a hollow body (7) by means of a machine (63) suitable for turning, milling and / or drilling workpieces about a rotation axis (D), the method comprising: - positioning a hollow body holder (31) in a desired position relative to a chuck (53) of the machine (63), wherein two spacer stops (33) of the hollow body holder (31) are aligned towards the chuck (53) of the machine (63), - Fixing the hollow body (7) by means of the hollow body holder (31), - holding and aligning a necking cone (15, 37) inside the hollow body (7) to the opening (5) of the hollow body (7) to be necked out, - Detachable and tensile-resistant connection of the necking cone (15, 37) held and aligned on the inside of the hollow body (7) to the opening (5) of the hollow body (7) to be necked out, with a free end (39) of a spindle rod (27), - placing a spacer (29) with a spindle rod passage (28) and a rotatably mounted spindle nut stop (30) on the spindle rod (27) so that the spindle rod (27) extends through the spindle rod passage (28) and the spindle nut stop (30) strikes a spindle nut (23) screwed onto the spindle rod (27), - clamping the spindle nut (23) into the chuck (53) of the machine (63) so that the spindle rod (27) extends coaxially to the rotational axis (D) of the machine (63), and - Rotating the spindle nut (23) by means of the machine (63) on the spindle rod (27) so that the spindle rod (27) moves axially towards the chuck (53) of the machine (63) and the hollow body (7) is held at a distance from the spindle nut (23) by means of the spacer (29), while the necking cone (15, 37) is pulled out of the hollow body (7) by the spindle rod (27) from the opening (5) to be necked out, wherein two hollow body holder stops (35) of the spacer (29) each strike against one of the spacer stops (33) of the hollow body holder (31). [14] The method of claim 13, further comprising the steps of: - machining the opening (5) in the hollow body (7) fixed in the hollow body holder (31) by means of a drilling and / or milling tool (13, 64, 66, 69, 70) clamped in the chuck (53) of the machine (63), and - Removing the drilling and / or milling tool (13, 64, 66, 69, 70) from the chuck (53) of the machine (63) when the opening (5) in the hollow body (7) has been machined. [15] The method of claim 13 or 14, further comprising: - Lubricate the neck cone (15, 37) with a lubricant. [16] A method according to any one of claims 13 to 15, the method further comprising: - loosening the spindle nut (23) and removing the neck cone (15, 37), spindle rod (27) and spacer (29) when the neck cone (15, 37) is completely pulled out of the necked opening (5) in the hollow body (7), and - Planing an axial end face (8) of the necked-out opening (5) of the hollow body (7) by means of a drilling and / or milling tool (71, 73) clamped in the chuck (53) of the machine (63).

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