EP1095739B1 - Press tool and method of cold-working a connection between workpieces - Google Patents

Abstract

The press tool for bonding two pipe workpieces (2,3), in a cold shaping action, gives bonding zones at the circular outer circle shapes of the pipes (2,3) which are pushed into each other.. The press pads (10) match the outer cross section shape of the workpieces, when closed together, and can have openings (13,17). The press tool can also have two press pads (10) and a mounting bolt. On applying the press force (F), the cold shaping forces are transferred to the workpieces (2,3). The gap (A) between the press pads (10) is adjusted according to the mfg. tolerances of the workpieces (2,3).

Description

The invention relates to a pressing tool according to the preamble of claim 1 and a method for cold forming joining according to the preamble of claim 20.

Such pressing tools are also available as press chains, press slings or press rings known and are used in particular for connecting pieces of pipe. For for this purpose, the pipe ends to be connected are placed in a deformable sleeve, a so-called press fitting. For cold forming joining one first press jaws like a cuff that is open at one point remains around the press fitting, leaving the two in the open position Chain ends of the pressing tool face each other. The initiation of Driving forces cause the two chain ends to contract. Thereby the inner sides of the press jaws become an annular stop Press room merged and the cold forming forces on the press fitting transfer. To ensure the radial cold forming of the fittings is as uniform as possible to ensure, are now in practice for cold forming joining of pipes with a diameter larger than 54 mm at least three in the Typically chain-like press jaws are used.

EP 627273 describes a pressing tool with more than two pressing jaws, which in a link guide are partially movable in the circumferential direction, whereby the Press jaws are arranged evenly over the circumference and thus one enable uniform radial distribution of the forming forces and a Prevent burr formation between the press links.

As shown in EP 627273, press tools are required for cold-formed Pipe connections with larger outer cross-sectional diameters, in particular for pipe systems with high internal pressure loads, more than two Pressing jaws. Thus, a "leakage" of the press fitting or the formation of a Press burrs between the end faces of the press jaws when closing the Press tool can be prevented, which means a complete closing and thus connected has made reliable connections impossible.

EP 0 361 630 discloses a press fitting consisting of a plurality of jaws which are in the closed state have a lemon-shaped cross section. It deals However, this device is not actually a pressing tool Senses, and the jaws are therefore not hinged connected to each other. EP 0 426 378 discloses a similar device, again with unconnected molds.

US 4,426,761 discloses a clamping device for exhaust pipes, consisting of a ring and two dies with a bolt be held together.

DE 198 03 536 discloses a pressing tool with several pressing members, wherein an attempt is made here to form the burr by interlocking teeth to prevent the press jaws.

Such pressing tools are for example in DE 4240427 and EP 922537, also described in so-called self-retaining designs, the itself before the introduction of the driving forces by spring elements pull the pre-tensioning forces together and therefore not in the alternative to Example with one hand, must be held on the workpiece in order to To prevent slipping or falling off the connection point.

The invention has for its object to provide an easy to use to create a structurally simple and flexible pressing tool or a method for cold-forming joining of nested Describe workpieces, which is a safe and reliable connection of workpieces with larger external cross-sectional shapes as well Connections with relatively extensive cold forming possible. Such Crimping tools should also be usable in confined spaces and, if necessary, grasp the workpieces to be joined in a friction-resistant manner.

According to the invention, this object is achieved by the characterizing features of claims 1, 6, 18 and 20 solved. Beneficial and alternative Embodiments of the invention are in the dependent claims cited.

The pressing tool according to the invention is designed with two arms, the press jaws also being advantageous for forwarding the introduced ones Driving forces are used. The press jaws must face each other be movably connected, wherein the connecting ends of the Press jaws over bearing bolts as structurally simple and reliable Connection concept has proven.

The cold forming forces exerted by the press jaws on the workpieces are triggered by drive forces introduced into the tool. For the Introduction are areas of attack - such as recesses, holes, projections, Eyelets, hooks, etc. - at at least one point on the press tool provided. These can be on the non-bearing ends of press jaws for attaching an optionally connectable drive device to be appropriate.

If, for example, possibly with tubular workpieces predetermined, in particular circular, outer cross-sectional shapes mentioned are always workpieces with such a trained Understand connection areas.

A pressing tool according to the invention exercises on the inside of the Press jaws apply the cold forming forces on the workpieces in such a way that when the pressing jaws move against each other, the outer "runs out" Workpiece and thus the formation of a burr between the Press jaws is largely prevented. So that the front The inside edges of the press jaws do not cut into the workpiece and thereby trigger a burr formation, are at least one-sided, optionally also on both sides, for example in the on the end faces bordering areas of the insides widening recesses as after angled on the outside, for example widening towards the end faces Bevels provided. The insides can face the front Inside edges both angled outwards and convex, if necessary, gradually curved towards the inside edges, run outward. Those who break away to the outside, if necessary, angled, insides can than to the front Adjacent chamfers be formed on the inside edges. This angled lead-in chamfers are preferred depending on the processing flat, but can also be slightly concavely curved. if the Insertion bevels are slightly concave, their curvature is less strongly formed than that of the rest of the inside, e.g. B. one Shell surface segment of a rotating body, possibly also less than the outer cross-sectional diameter of the outer workpiece before the Cold forming, while the curvature of the inside of the Inner side areas adjoining insertion bevels at least approximately the remaining outer cross-sectional diameter of the cold-formed Workpiece corresponds.

Due to these features, the bevels on the inside are on your front inside edges so shaped that when applied to the Do not work the inside with the front inside edges sit on, but inside, possibly tangentially, optionally spaced from the front inside edges, on Fit the outer jacket of the workpiece.

The extent of the outward angling of the outer end face Inner side areas depend on the outer cross-sectional diameter of the respective workpieces assigned to the pressing tool. at External cross-sectional diameters between 54 mm and 108 mm can Entry bevels, for example at an angle of 5 to 25 ° to the outside be angled to the directly adjacent lateral surface.

At least two are required for the function of a pressing tool according to the invention Press jaws necessary. The two press jaws can be moved by one common bearing pin can be mounted, the bearing pin if necessary is eccentric. An eccentrically designed bearing pin causes that when the pressing tool is opened, the non-bearing end faces of the Press jaws experience an additional translational movement apart. As a result, the necessary opening angle for a circumference of Workpieces and the distance between the end faces in the preloaded state of the Tool can be reduced.

The two press jaws can also have two in one bearing bracket Hinge pins are stored individually. Here again if necessary, at least one bearing pin can be formed eccentrically. The Both bearing bolts are both rigid and rigid in the bearing bracket can be stored coupled together. For example, to move relative A guide slot is provided in the bearing bracket for each bearing pin be along which the bearing pins are displaceable, and if necessary the Bearing pin to be connected via a guide linkage.

The eccentric design of the bearing bolts and the individual bearings of the Press jaws are also suitable for those embodiments in which the Inner sides of the press jaws do not have lateral surface segments of Have rotational bodies, i.e. that the press tool in the closed Instead of an annular space, it has a polygonal or oval shape encloses trained space.

To create the pressing tool around the workpieces to be connected facilitate and in particular its falling before starting a if necessary to prevent coupling device, it is advantageous, the pressing tool in the closing direction with pre-tensioning forces to provide exercising agents. For the self-holding function of a Press tool is at least one pretensioning force in the closing direction exercising agent necessary. This can be between the individual Press jaws can be arranged and / or the pressing tool as one-sided Clamp open clip. As the means exerting the preload on the one hand, the pressing tool on the workpieces does not slip has to clamp, and on the other hand the press tool is still slightly closed opening and to place the workpieces, preloads are exerted Medium with relatively long spring travel is an advantage. This is preferred Coil springs versus leaf or bar springs, especially at Press tools where the opening of the tool is large Relative movements require fewer parts. As a preload Different components made of different, elastically deformable materials. Metallic springs are preferred, however also means made of rubber-like materials such as drawstrings or stretchable Plastics are conceivable. You can between the press jaws and / or around these are attached outside. Wound around bearing bolts Coil springs, the spring ends of which each on a press jaw Applying pre-tensioning forces allows for structurally simple solutions comfortable handling.

The shape of the inside of the pressing jaws of the pressing tools is not on Shell surface segments of rotating bodies with identical Radii of curvature limited. Are the workpieces in the connection area not rotationally symmetrical, but for example ellipsoidal, polygonal or irregularly shaped, or is said to be reshaped into such a shape are other, the external cross-sectional shape of the workpieces suitably adapted training of the inside is possible.

To support the positioning and guiding of the pressing tool Workpieces can also on the inside of the press jaws - if necessary, the entire inside circumferential protuberances and / or Recesses such as Notches or grooves.

Because the press jaws can be made in a very narrow design and around their Bearing pins are largely pivotable freely, this is the inventive Not only to place the pressing tool simply and easily around workpieces, but also for confined spaces, such as those found in wall installations on the ceiling and in corners can be found, particularly suitable.

An inventive, cold forming joining process from two to part nested workpieces with a predetermined, in particular circular outer cross-sectional shape, takes into account the given Manufacturing tolerances of the workpieces to be connected in the connection area. Due to the tolerances of fittings, sleeves and pipes, for example, especially with the large connection nominal sizes DN (50 to 100) the necessary driving forces for merging the Press jaws of a press tool to a closed press room vary considerably. This makes the drive devices and tools to be dimensioned according to the maximum occurring forces. in the In contrast, the inside of the press jaws are one Press tool according to the invention designed so that a reliable, cold forming connection when a predetermined force is reached, even at a tool that is not closed. in the Interaction with a drive device, which for the respective Connection processes specific driving forces on the tool initiated are controlled connections with lighter and more flexible Tools and drive devices possible.

Fig. 1

einen Querschnitt durch ein erfindungsgemässes Presswerkzeug, welches zwei zu verbindende Werkstücke umfängt;

Fig. 2

einen vergrösserten Ausschnitt einer Pressbacke des Presswerkzeuges aus Fig. 1;

Fig. 3

einen Querschnitt durch das Presswerkzeug und die Werkstücke aus Fig. 1, auf welches Antriebskräfte eingeleitet sind;

Fig. 4

einen Radialschnitt durch eine Ausgestaltungsform der Innenseite einer Pressbacke;

Fig. 5

einen Querschnitt durch ein Ausführungsbeispiel eines erfindungsgemässen Presswerkzeuges mit zwei Lagerbolzen und

Fig. 6

einen Querschnitt durch ein Presswerkzeug mit drei Pressbacken.

The invention is described below purely by way of example with reference to exemplary embodiments shown in the drawing.
Show it:

Fig. 1

a cross section through a pressing tool according to the invention, which includes two workpieces to be connected;

Fig. 2

an enlarged section of a press jaw of the pressing tool of Fig. 1;

Fig. 3

a cross section through the pressing tool and the workpieces of Figure 1, to which driving forces are introduced.

Fig. 4

a radial section through an embodiment of the inside of a press jaw;

Fig. 5

a cross section through an embodiment of a pressing tool according to the invention with two bearing bolts and

Fig. 6

a cross section through a press tool with three press jaws.

Fig. 1 shows a tubular fitting 2, which in part on a pipe 3 with circular outer cross-section is pushed on. Because of your Manufacturing tolerances are between the fitting 2 and the pipe 3 each different sized empty space 9 available. The fitting 2 can Be gunmetal fitting or machined from a corresponding blank be made. A pressing tool according to the invention has two Press jaws 10, a coil spring 5 and a bearing pin 4. The Pressing tool surrounds the fitting 2 and lies on the coil spring 5 biased to the fitting 2 in the biased condition. The press jaws 10 are essentially identical in mirror symmetry. You point same features with the same functions and reference numbers. The Press jaw 10 is semicircularly curved. On a warehouse side Front 16 of the press jaw 10 are bearing tabs 14, if necessary attached in pairs and symmetrically to the central plane, which with a Bore are provided. A non-bearing end face 11 forms that other end of the arcuate press jaw 10. The press jaw 10 has in Area of the non-bearing end face 11 directed against it Attack area 18 for introducing drive forces F (as in FIG. 3 shown). For the introduction of preload forces through a spring end the screw end 5 in the press jaw 10 is on the end face 16 adjacent introductory area 15 is provided. For better management of the The introduction region 15 can be provided with a groove at the spring end. Two parallel side walls 19 which act as stiffening ribs give the press jaw 10 additional rigidity. The press jaw 10 has an inside 12, the surface of which by a lateral surface half Rotational body and by two bevels 13, 17 is determined. It are also training with only one bevel or according to the Fig. 5 without any bevels, especially for connections of medium and smaller external cross-sectional shapes possible. In a manner known per se the bearing tabs 14 on the bearing end faces 16 of the two Press jaws 10 each offset from one another, so that the Bores of all bearing plates 14 are aligned coaxially with each other can. The bearing pin 4 inserted into the aligned bearing holes connects the two press jaws 10 rotatably supported with each other. So that will the fitting 2 can be encompassed by the pressing tool. In the several turns around the bearing pin 4 coil spring 5 conducts prestressing forces into the Introductory areas 15 of the two press jaws 10. As a result, the two lie Press jaws 10 on the fitting 2 frictionally and secure the pressing tool against slipping or falling.

FIG. 2 is an enlarged section of FIG. 1 and shows one possible one Design of the inside 12 with inventive bevels. The Inner side 12 is in the form of a lateral surface half of a cylinder Diameter D formed. From this shell surface half is from the to non-bearing-side end 11 bordering area of the inside 12 a bevel 13 not on the bearing side. The non-warehouse side Bevel 13 widens towards this end face 11. The non-bearing-side bevel 13 is on a length L from the The outer surface shape of the inside 12 is excluded and with an angle W formed inclined against this lateral surface. The not shown in Fig. 2, area bordering the bearing end 16 can be a Mirror-symmetrically identical bevel 17 on the bearing side exhibit. The edges of the bevels 13, 17 with the end faces 11, 16 can be provided with a radius. This will slip the Press tool 1 on the fitting 2 facilitated. Is in the prestressed state the tool on the bevels 13, 17 on the fitting 2.

Below are dimensions of the diameter D, the angle W and the length L for an embodiment of press jaws 10 according to the invention for the nominal widths DN (German standard) 40, 50, 65, 80, 100, 2 1/2 ", 3", 4 "of System provider "Viega, Franz Viegener II, D-57428 Attendorn" and likewise for the nominal widths DN 40, 50, 65, 80, 100 of the system provider "mapress, Mannesmann Pressfitting-System, D-40764 Langenfeld" are shown in an exemplary table have proven to be suitable for cold-forming connections with a pressing tool, corresponding to the exemplary embodiment from in FIG. 1. D, W, L depending on nominal size DN, pipe and fitting Nominal size [DN] Pipe [material] Fitting [material] Diameter D [mm] Angle W [360 °] Length L [mm] 40 Edelst./Cu Edelst., Rotg. / Cu 51.9 7.5 2-3 50 Edelst./Cu Edelst., Rotg. / Cu 63.9 8.5 3-4 65 Edelst./Cu Edelst., Rotg. / Cu 76.1 12.5 4-8 80 Edelst./Cu Edelst., Rotg. / Cu 102.0 12.5 4-8 100 Edelst./Cu Edelst., Rotg. / Cu 121.0 15.0 4-8 2½ " Edelst./Cu Edelst., Rotg. / Cu 78.0 12.5 4-8 3 ' Edelst./Cu Edelst., Rotg. / Cu 91.5 12.5 4-8 4 ' Edelst./Cu Edelst., Rotg. / Cu 116.5 15.0 4-8

FIG. 3 shows the pipe 3, the fitting 2 and the pressing tool from FIG. 1 in the driven state. Driving forces F are not greater than one in FIG shown, for example detachable drive device on the Attack areas 18 of the pressing jaws 10 are introduced into the pressing tool. Starting from the prestressed state of FIG. 1, the Press jaws 10 against each other. The bevels 13, 17 lie on the Surface of the fitting 2 and exert forming forces on the fitting 2. Between the edges between the end faces 11, 16 and Bevels 13, 17 and the surface of the fitting 2 is a certain Given scope. This will prevent the formation of a ridge between the opposite end faces 11, 16 substantially prevented. Through the Forming forces exerted by the pressing tool is the fitting 2 in essentially oval-shaped until it covers the lateral surface halves of the Inside 12 touched. By moving the Press jaws 10, the fitting 2 is further formed until it is completely on the Shell surface halves abuts. Since their diameter D (Fig. 2) is smaller than the outside diameter of the fitting 2 flows with these deformations Material of the fitting 2 against the pipe 3. With another Moving the pressing jaws 10 against each other flows next to the material that is in the bevels 13, 17 flows, further material inwards and exercises Compressive forces radially on the tube 3. The tube 3 is now with the cold-formed fitting 2 reliably connected. Another one Moving the pressing jaws 10 against one another now increases the driving forces F disproportionately, even if the pressing jaws 10 with their Do not touch non-bearing end faces 11 and a distance A from each other. Given the driving forces F, the distance is A of the manufacturing tolerances of the dimensions in the connection area of the Fittings 2 and the tube 3 dependent.

The cold-forming process according to the invention is based on this fact Connection method for partially pushed workpieces. in the Contrary to the usual pressing tools for one reliable connection of the workpieces does not drive as long initiated until the press jaws have touched each other, but the Press jaws 10 are moved against each other until the driving forces F have reached a predetermined amount. A corresponding The drive device therefore has an adjustable regulation of the maximum to be initiated drive forces F and not, for example, only one, as in the Common practice, designed for a certain maximum pressure mechanical pressure relief valve, which is only a constant upper limit for the Guaranteed amount of driving forces. As is easy to see, the Diameter D (Fig. 2) with the extreme values of the manufacturing tolerances Dimensions of the workpieces that connect the cold forming influence, so that it is always a reliable, cold forming joining is guaranteed, both when the non-bearing end faces 11 - depending on the tolerance conditions - except approach a distance A, as well as when the end faces 11 touch. As Example is for a connection of, for example, a gunmetal fitting with a stainless steel tube - with a nominal diameter of 108 mm - with a tool which is essentially that shown in FIG Embodiment corresponds, the distance A usually about 2 mm +/- 1 mm. The driving forces required for cold forming are in one On the order of approximately 32 kN.

Fig. 4 shows a radial section along the line I-I of Fig. 3 with viewing direction in the direction of the arrow through a possible design variant of a press jaw 10. Depending on the design, the inside 12 can have a circumferential, have semi-toroidal protuberance 22 or a circumferential notch 23. The inside 12 is covered by a lateral surface segment of a rotating body certainly. The protuberance 22 and the notch 23 are in the area of Bevels 13 continued parallel to these. The semi-toroidal Protuberance 22 supports the positioning and guiding of the press jaw 10 on a corresponding fitting 2 during cold forming joining. The Notch 23 is provided for a possible bulge of the fitting 2.

5 shows a further exemplary embodiment of an inventive one Press tool, the two mirror-symmetrically designed, single-bearing Press jaws 20, in contrast to the press tool from FIG. 1, over two Bearing bolts 4 are each individually rotatably supported. The two bearing bolts 4 are in turn mirror-symmetric in a manner known per se identically designed bearing brackets 7 held. The both sides of the individually mounted press jaws 20 are mounted mounting brackets 7 each with two bearing bores. In the plane of symmetry between the two bearing bolts 4, the bearing brackets 7 have guides for inside a role 8 on. The roller 8 engages in a semi-cylindrical shape Recess 28 of the bearing end 26 of both individually supported Press jaws 20 and thus forces this to open symmetrically Pressing tool. If necessary, training variants are included Bevels (Fig. 2), especially for tools for large Connection diameter to be considered. Two mirror-symmetrical identically designed coil springs 5 which lead around the bearing bolts 4 20 pre-tensioning forces in the individually stored press jaws Position the press tool on a fitting in a self-retaining manner.

Fig. 6 shows a comparative example of a Press tool, which in contrast to the press tool from FIG. 5 three has pressing jaws connected to one another in a chain-like manner. Two Arc-shaped end jaws 30 of the same symmetrical design are identical one end with the ends of a third arcuate central jaw 31 two bearing bolts 4 rotatably connected to each other in a conventional manner. In the non-bearing-side end area of the end jaws 30 are analogous to that Press jaws 10 from Fig. 1, attack areas 38 for the initiation of Driving forces F attached. The end jaws 30 and the middle jaw 31 can have essentially identical inner sides 12 with lateral surface segments of rotary cylinders, provided with bevels 13, 17. Two mirror-symmetrically identically designed, the bearing bolts 4 winding Coil springs 5 lead into the end jaws 30 and into the middle jaw 31 in Closing direction preload forces, which press tool on a fitting position self-holding.

Claims (22)

1. Pressing tool for connecting workpieces (2, 3) having a predetermined outer cross-sectional shape by cold forming, which pressing tool has at least two pressing jaws (10) which are connected so as to be movable towards one another, exert cold-forming forces on the workpieces and have in each case two end faces (11, 16) and an inside (12), the inside (12) of the pressing jaws (10) being designed in such a way that, after cold forming has been effected, the inside region (12), pointing towards the workpiece (2, 3), of the pressing jaws corresponds essentially to the outer cross-sectional shape of the workpiece, characterized in that the pressing jaws (10) have a recess (13, 17) on the inside (12) following the end faces (11, 16), widening relative to the outer cross-sectional shape of the workpiece being effected in the region of the recess.
2. Pressing tool according to Claim 1, characterized in that, after cold forming has been effected, the at least two end faces (11) of two pressing jaws (10, 20) are at a distance from one another, the inside region bearing so completely against the outer lateral surface of the workpiece that a closed pressing space results.
3. Pressing tool according to Claim 1 or 2, characterized in that the at least one recess is assigned to one of the end faces - at one end and/or at the other end.
4. Pressing tool according to one of the preceding claims, characterized in that the recess is of planar design.
5. Pressing tool according to one of the preceding claims, characterized in that the recess is of curved design, the curvature having at least two regions with different radii of curvature.
6. Pressing tool according to one of the preceding claims, characterized in that, before the cold forming, the workpiece in the inside region is in contact only in the region of the at least one recess.
7. Pressing tool according to one of the preceding claims, characterized in that the recess is configured as a bevel widening towards the end faces and angled outwards.
8. Pressing tool according to Claim 7, characterized in that the bevel is flat, convexly curved or concavely curved.
9. Pressing tool according to Claim 8, characterized in that the bevel is curved to an increased extent convexly and gradually towards the inside edges of the end face.
10. Pressing tool according to one of the preceding claims, characterized in that the pressing tool has engagement regions (18) for the driving forces (F) necessary for the cold forming.
11. Pressing tool according to one of the preceding claims, characterized in that the insides (12) of the pressing jaws (10, 20) have lateral surface segments of bodies of revolution.
12. Pressing tool according to one of the preceding claims, characterized in that the -pressing jaws (10, 20) are connected via at least one bearing pin (4).
13. Pressing tool according to Claim 12, characterized in that the bearing pin (4) is of eccentric design.
14. Pressing tool according to Claim 12, characterized in that the pressing jaws (10, 20) are mounted via two bearing pins held in a bearing retainer.
15. Pressing tool according to one of the preceding claims, characterized in that the pressing tool is provided with a means exerting preloading forces in the closing direction.
16. Pressing tool according to Claim 15, characterized in that the means exerting preloading forces in the closing direction is arranged between and/or around the pressing jaws.
17. Pressing tool according to Claim 15 or 16, characterized in that the means exerting preloading forces in the closing direction is a spring.
18. Pressing tool according to Claim 17, characterized in that the means exerting preloading forces in the closing direction is a helical spring.
19. Pressing tool according to Claim 18, characterized in that the helical spring is arranged so as to wind around a bearing pin.
20. Method of connecting workpieces (2, 3), pushed at least partly one inside the other and having a predetermined outer cross-sectional shape, by cold forming using a pressing tool according to Claim 2, comprising the following steps:

    opening the pressing tool,

    enclosing the workpieces (2, 3) with the pressing tool,

    introducing the driving forces (F) directly onto the workpieces (2, 3) via engagement regions (18, 38) of the pressing jaws (10, 20) provided for this purpose by means of a drive device, the pressing jaws being moved towards one another until the inside region bears so completely against the outer lateral surface of the workpiece that a closed pressing space results and the driving forces, when the end faces (11) of two pressing jaws (10, 20) are at a distance from one another, have reached a certain magnitude dependent on the respective materials, manufacturing processes and dimensions of the workpieces (2, 3).
21. Method according to Claim 20, characterized in that a pressing tool according to one of Claims 3 to 15 is used.
22. Method according to Claim 20 or 21, characterized in that a drive device with coupling facility is used.

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