DE1752739A1 - Machine for cold forming of tubes to smaller diameters - Google Patents

Description

M 00960 KaAa

Kent-Owens Machine Company 958 Wall otreet, Toledo, Ohio, USA

Machine for cold forming tubes to smaller ones

diameter

The invention "relates to a machine for ivalt forming from drilling to smaller diameter and extending in particular on improvements to the support and support frames for the die holder and an improved drive for this.

machines for cold forming tubes to smaller ones Diameters are generally a pair with each other related die or forming roles that perceive in a reciprocating or Saddle are attached, which on my part for the and moving movement is a bit long

109827/0263 ^{BAD or |} g'nal

Pipe is guided and held, which is rolled and up a smaller diameter is formed. Such saddles are necessarily massive to withstand the pressure, which is used in cold forming. The driving force required for the back and forth movement of the saddles is also considerable. In the end the number of work cycles that can be achieved per unit of time is quite limited.

machines for cold forming of tubes have already become proposed to smaller diameter, the dies of relatively large diameter and which are moved back and forth over a relatively small angle and by a fixed frame are held. The way in which these mold rolls are held and driven, but causes a significant proportion of sliding or Hutech movements between the forming rollers and the Kohr. This· Appearance leads to rapid wear and tear and also causes carriage marks on the surfaces of the finished products. In addition, a large amount of heat is generated, which generates a corresponding energy

alai tor ·! ti Ytr «cki« 4 «n · species worn. Maechia * sur

BATH ORIGINAL

Cold forming of tubes to smaller diameters has been proposed have been, in which the (sinks are held and moved to and fro in such a way that a proportionately small amount of sliding movement occurs. However, these machines disadvantageously have complicated holding and driving devices on, which leads to a considerable increase in the cost of the machine and an increase in maintenance problems have led. In addition, the dies of such machines are the tube to be formed have only detected during one half of the work cycle and separated from the pipe during the return are. This necessarily leads to a considerable reduction in their output Machinery.

The present invention relates to an improved machine for cold forming tubes to smaller diameters with many advantages over the previously known types of machinery. The new machine includes one Pair of large diameter dies held in a fixed frame instead of a reciprocating one Frame attached, as well as simplified load-bearing components for the dies and the counterbore holder. Even though The components are simply designed, yet they are shaped so that the dies don't tend to

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slide down the pipe. The machine also has an arrangement to coordinate the reciprocating movements of both die holders relative to one another, The two are also coordinated with respect to the frame in order to ensure precise guidance and monitoring to ensure their movements. The drive device for the die holder of the new machine is also there versatile, only one of the two die holders is direct driven, while the second is driven indirectly by a new lever arrangement through which the second Die holder is connected to the first. This arrangement eliminates the need for the drive to coordinate devices for each die holder individually, as was previously the case. the The dies of the new machine are preferably set back somewhat in the die holder when viewed from the tube so that the two dies never touch each other. This arrangement reduces the risk of damage to the dies, which are made of hardened metal and ordinary, is considerable Are subject to fractures.

It is therefore an essential object of the present invention to provide an improved cold forging machine from Kohren to smaller diameters with many advantages

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to create compared to the previously known types of machines.

One object within the scope of this aim according to the invention is to develop a machine for the forming of pipes with simplified load-bearing components for the die holder to create, with the effect that the Dies can work with an extremely small amount of sliding movement.

Another object of the invention is to provide a machine for forming tubes with a Drive device that enables the two die holders to work in a coordinated manner.

After all, the new machine for forming Tubes have an improved arrangement for synchronizing the work cycles of the die holder.

Numerous other aims and advantages of the invention will become apparent from the following description, in which a preferred embodiment according to the invention is referred to. alt) -iichriurigen l: u fmr.jolnen erUiuterc, vi.'d> .u len

Fig. 1 is a side view of a machine for forming tubes according to the invention, wherein various parts are broken away, and of devices for delivery, supply and Rotating a pipe to be formed;

FIG. 2 is a plan view of a device according to FIG. 1j

Fig. 3 is an enlarged view of an inventive Device as a vertical section along line 3-3 of fig. 1;

4 is a side view of a machine for forming of tubes according to FIGS. 1 and 3 "but on a somewhat smaller scale than in Fig. 3, with various parts broken away and other parts shown again in section)

Figure 5 is a rear view of the machine of Figure 4 with various parts removed;

6 is an enlarged partial view in vertical section taken along line 6-6 of FIG Fig. 3;

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Fig. 7 is a rear view of the components of Fig. 6j

8 is a schematic view for illustration

different length ratios and relationships between various components of the Machine according to the invention.

From Figs. 1 and 2, a machine 10 for cold forming of pipes to smaller diameters after Invention seen with a conventional device for feeding and rotating a tubular Blank in accordance with the working of the forming machine. This coordination is achieved by a Actuating gear 12 brought about the devices for feeding and turning is coordinated with the work cycle of the machine 10. The rotating device 14 is by a Gear connection 16 synchronized with a rotating device 18 so that the tube at both ends of the Machine cycle rotated, but only at one end of the Machine cycle is moved a little further in the longitudinal direction. The devices 14 and 18 are known and are not explained in detail. A blank 20 is usually about 2438 mm to 4876 mm long before it is transformed, according to a practical example the carbon ring 20 initially has a diameter of 88.9 mm, which is reduced to 65.5 mm, connected to a

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Reduction in the thickness of the pipe wall from 12.7 now to 6.35mm when the blank leaves the machine 10 · The Tube can be guided about 6.35 mm in the axial or longitudinal direction each time the die components of the machine 10 reach the cortex of their movement to have. Furthermore, the pipe can be rotated by 4 ° every time the (ie lowering ei Ie the end of its movement achieved. Depending on the particular working method, the forward movement of the Kohr vary between about 6.35 mm up to 25.4 mm, while the rotation can vary from approximately 20 degrees up to 6u degrees, a mandrel is inserted inside the itohr in a conventional manner to control the inside diameter. In particular from FIGS. 3 to 5 it can be seen that the tube forming machine 10 is a stationary one Frame 22 comprises a swaging device 24 and a lower die device 26. The fixed Frame 22 has a drive housing or a base plate 28, lateral frame members 30 and 32, upper ückstützen 34 and an upper üestellglied 36.

The upper die assembly 24 includes an upper axis or abutment roller 38, which is supported by the upper frame member 36 by means of support parts 40 and 42 as well as bearing

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flange parts 44 and 46 is held. Among other things, the axis 38 is pushed upwards during a forming operation, only relatively small forces are applied to the bearing parts 44 and 46.Roller bearings 48 and 5 are rotatable on the spaced apart cylindrical components 52 and 54 of the axis 58 Mounted in link lever 56 has upwardly directed cheeks 58 and 6u which are rotatably supported on roller bearings 48 and 50 and are provided with respective covers 62 and 64 which extend around bearings 48 and 5u. It is not necessary for the vents 58 and 60 to extend completely around the bearings 48 and 50, since most of the portion of the jiraft allotted to the lever 56 is directed upwards. J) The covers 62 and 64, however, serve to hold the cheeks 58 and 60 in place on the bearings 48 and 50 at the ends of the work strokes when little or no pressure is applied to the dies. The lever 56 also includes a pair of external, cylindrical components 66 and 68 which carry further roller bearings 70 and 72. Stub shafts 7 ^ and 76 in addition to the cylindrical components 66 and 68 take on bearing caps 78 and 80 , which also extend upwards around the bearings 70 and 72, and the fog 56 has a cylindrical projection 82 which extends over the stub shaft 76

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protrudes to take up an actuation lever that continues is described below.

An upper die holder or die block 84 is arranged below the connecting lever 56 and has upper cheeks 86 and 88 which are rotatably mounted on the roller bearings 70 and 72, the outer covers 78 and 80 are attached to the die holder 84 and help to to support the connection between the die holder and the connecting lever 56, in particular during the reversal times within the working cycles of the uesenke. The lower jaw holder 84 extends over an angle of 30 degrees and carries a toothed segment 90 on one side, which meshes with a toothed segment 92, which forms part of the lower die assembly 26. The lower toothed segment 92 in turn meshes with a toothed rack 94, which from the actuating element 30 is held. This structure ensures a coordinated movement of the die holders of the arrangements 24 and 26. At the same time, it is possible to avoid sliding movement of the two dies in relation to the drill to be formed and in relation to the frame. ^ΰ 1 · β · β feature of the machine · for cold forming of tubes makes a significant contribution to the extraordinarily good quality of the end product ·.

109827/0253 ^ ₀ original

The die holder 84 has a central, longitudinal direction extending groove or recess 96 in which an upper die or die insert 98 is carried is. The lower surface of the die 98 is curved, and similar to the lower surface of the die holder 84. However, the lower surface of the die only extends over an angle of about 23 degrees compared to that Angle of about 32 degrees for the die holder. The lower surface of the die 98 is preferably slightly upward set back with respect to the surface of the die holder 84, namely by about 79 mm »which allows that the pressing pressure is exerted between the die holders and not between the dies. The slight gap does not affect the shape of the tube to be formed, because the die in each case has edges forming an enlargement, formed by a surface which is semi-cylindrical in cross-section so that the edge areas of the die do not participate in the forming of the metal anyway then not when the dies touch. A forming surface 100 of the die has a substantially semicircular shape in cross section, with the radius at the front end (left end with reference to Figures 4 and 6) exceeds the radius at the rear or right end. Corresponds to the front end

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the radius of the die surface 100 is essentially the radius of the tube or blank that is to be cold formed, and the radius along a section at the opposite end is substantially the same as that desired End radius of the pipe

The die 98 is adjustable and precisely adjustable in the rage 96 of the die holder by means of a holding and Arranged adjusting device, which is shown in FIG. This arrangement allows adjustment of the Die insert in the vertical as well as in the transverse and longitudinal direction. For vertical adjustment there is one upper lining plate 102 placed on the upper wall of the fury, the die being secured by suitable screws 104 is pressed against this lining plate. For a transverse adjustment, the groove is precisely arranged with a Provides surface in the longitudinal and vertical directions against which the die 98 is pressed by a side wedge 106, which is adjustable in the longitudinal direction by a set screw 108 and a locking screw 110. For an adjustment in the longitudinal direction, the die has beveled ends with two end wedges 112 and 114 come into engagement, which are adjustable in the vertical direction by means of screws 116 and 118. One Spacer plate 120 is between the wedge 114 and the

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End wall 122 of die holder 84 arranged while an abutment support 124 behind the wedge 112 is inserted and attached to the die 98. The settings compensate for the wear of the die 98 and also allow precise control of the final diameter of the pipe.

As can be seen from Figures 3 to 5, the lower die assembly 26 has similar basic components as the upper die assembly 24. The former will therefore not be described in so much detail. A lower die or die insert 126, which has a substantially semicircular cross-section Pormflache 128, similar to the surface 100 of the die 98, is housed in a die holder 130 and set back in this by about 0.79 nm, in this way a small Provide about 1.58 mm clearance from the die 98. The die holder 130 is essentially identical to the die holder 84 and, as already mentioned, carries the toothed segment 92, since on the one hand with the toothed segment 90 and on the other hand with the toothed rack 94 in singular engagement in order to ensure a coordinated movement with the die holder 84 and around to avoid sliding of the two dies relative to the drill or the frame.

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Die holder I30 includes a pair of downward facing Cheeks 132 and 134, which are rotatably mounted on a pair of roller bearings 136 and 138 with covers 140,142 extending around them and attached to the die holder 130. The roller bearings 136 and 138 are attached to cylindrical members 144 and 146 of a lower link lever 148. The connecting lever 148 includes downward facing cheeks 150 and 152 mounted on roller bearings 154 and 156 with covers 158 and 160 which extend around there. The bearings 154 and 156 are on cylindrical end members 162 and 164 attached to a lower axle or abutment roller 166 "

The axle 166 has a central, cylindrical bearing part 168 which is rotatably supported on a bearing block 170 which has a bearing half cover 172. The block I70 is carried by an adjusting wedge 174 which can be moved in the longitudinal direction by means of an adjusting screw 176 (FIG. 4) in order to apply a preselected preload to the pivot holder. A considerable preload force is required to avoid separation of the genes. Yes · for example, for a head with a · »diameter of 88.9 mm and a wall diok · of 12.7mm« in · Jlraft of at least 1360 ^ 8 kilograms b · -

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compels. This load depends on the type of material that To be machined, required to be the outside diameter to 63.5 mm with a wall thickness of 6.35 mm to decrease. The bearing block 170 and the Jüager are also supported by bearing blocks 178 and 18U arranged at the end (Fig. 4) and spacer plates 182 and 184, in order to create a broader base for the machine components during their operation.

Further support for the die components of the lower die assembly can be provided by two control cam parts or lugs 186 and 188 may be provided which are rotatable by axles 190 and 192 with the lower corner portions of the lower die holder 13u connected are. With the control rollers 186 and 188 two cam plates 194 and 196 cooperate, which in suitable Wise are attached to the frame 30 and have such a shape of the control edges that these the tracks the control rollers 186 and 188 closely follow during the pushing movements of the die holders 84 and 130. Strictly speaking the shape of the control edges is such that the control rollers engage the cam plates for the greatest amount of time the thrust movements do not touch, but they are primarily intended as abutment supports that emergencies at the reversal points of the work cycle of the die holder intervention. At the turning points of a working

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taktea is usually less weight and form pressure directly over the connecting levers, bearings and cons bearing rolls transferred.

The drive device of the forming machine 10 is described in more detail below. Preferably only will one of the two die assemblies 24 and 26 is driven. The other of the two arrangements is then through driven a connection between the two assemblies. This eliminates the need to coordinate single drives. Also, the cost the drive elements as well as the entire space requirement of the machine. As in the * 'ig. 3-5, the upper die assembly 24 includes a lateral operating lever 198 on, the one in the middle has an opening in which the lifting projection 82 is rotatably mounted. In addition, the actuating lever has an upper opening in which a projection 200 can be rotated is stored. The lower end of lever 198 is on a push rod 202 is articulated, which in turn is articulated to an eyelet 204 of a slide 206. The carriage 206 rests on a carriage guide part 208 and has a flange 210 which is fastened to the slide and is received in a groove 212 in the slide guide part 208

BATH ORIGINAL 109827/0253

Guide part 208, the carriage 206 has an eyelet 214, to which a lower push rod 216 is articulated. The lower push rod has a lower operating lever 218 connected. On this lever, a projection 220 of the connecting lever is in its central area 148 and at its lower end a projection 222 of the axle or the abutment roller 166. This drive connection allows one of the two die assemblies 24 and 26 to be driven by the other will. However, the die holders can advance and return and even separate slightly from one another during the rotation of the operating levers 198 and 21 θ.

In the exemplary embodiment selected and illustrated here, the lower die assembly 26 is driven. For this purpose, the lower die holder 130 has a Pair of forwardly extending levers 224 on which a pair of crank arms (compare Figs. 4 and 5) is articulated. These are in turn eccentrically connected to gears 228, which in turn are driven by gears 230, as well as by a drive shaft 2J2 and a pulley 234, the Connected to a suitable motor 238 via gills 236 are*

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If suitable dimensions for the connecting levers 56 and 148 and for die holders 84 and 130, the dies can be used during their work cycles can be reciprocated and kept under an appropriate pressure without moving the supporting frame 20 compared to the Bohr and without significant sliding. With regard to Fig. 8, this result is achieved in that the supporting lever and the die holder are Gestalltet such that the arc of the axis of the bearing part of the connecting lever 56, which arc during the rotation of the lever 56 about the abutment roller 38 arises, a part of an enlarged circular curve (prolate trochoidal), which in the following briefly called the pt curve, which curve would be formed by a point corresponding to the same axis of the lever during rotation of the die insert 96 As the arcuate path of the lever axis is substantially superimposed on the pt-axis, the joint insert 98 moves along a straight line without any transverse movement of the abutment axis 38 or the frame 22. The same applies to the lower connecting lever and the lower joint holder. It should be noted that the diameter of the die and the die holder is always the distance from the meeting die holder surface to the articulated connection of the

109827/0253 bathroom original

Connecting lever and the holder and also to the articulated connection of the connecting lever and the upper frame exceeds.

For example, when it comes to a reciprocating stroke length of approximately 660.4 mm achieved with dies 98 and 126 with radii R1 of 1524 mm it is necessary that these pass through an angle of 23 degrees. If you take the axis of the Bearing part of the lower end of the lever 56 on a Point 914.4 now from the center of rotation of the die 98 at a distance, where the distance D1 is then 609.6 mm, and given the effective length of the Lever 58 makes 425.45 mm long, so that the radius R2 425.45 mm, the desired result is achieved. This result consists mainly in the fact that the arc, which is described by the axis of the connecting lever becomes, essentially the pt curve over an arc of 11.5 degrees on this side and on the other side of a vertical plane is superimposed · deviates beyond approximately 11.5 degrees the arc of the axis of the connecting lever descends in an area above the pt curve, and the pressure of the dies 98 and 126 subsides. As a result, the Dies when the angular movement of the levers is continued. Of course, the different

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different factors such as stroke length, lever length, angle etc. in the various applications. Depending on the prevailing conditions, it can be desirable respectively may be required with dimensions other than those which are given in the previous example for the stroke length. The angle and length ratios of the upper die assembly apply equally to the lower die assembly 26.

According to the above, it is suggested that the arc of the lower axis of the connecting lever 56 be superimposed directly on a portion of the pt curve described by the same axis or point during the die stroke. Strictly speaking, however, the two curves do not exactly overlap, nor is it necessary that they exactly overlap. Rather, it is important that the arc and the curve above all overlap or cross at the time of the completion of the front stroke end of the dies, since this takes place where the rear portions of the sink 98 and 126 determine the diameter of the barrel. The die surface 100 does not have a continuous taper from one inde of the die y6 to the other end, rather the last 5Ό or 75 mm of the die, namely

109827/0253 ORIGINAL BATHROOM

corresponding to the last two or three arcs of the stroke, semi-cylindrical in cross-section and tapering not yourself. üJs these are those places of the -nube and the die, where the two curves are practically identical must be accurate with regard to their distance from the central axis of the shaft or axis 38 in order to be accurate.- and To ensure the correct dimensions of the finished tube, which has been brought to a smaller diameter.

Under the special conditions explained above, if the radius R2 of the u.ebels is 4-25.45 ^mm and the entire die stroke extends over an arc of 23 degrees, the arc and the pt curve must intersect at a point which 4-25.4-5 mm from the central axis of axis 38 and 11.5 degrees from a centerline through axis 38. That point is in Pig. 8 marked with P. In angular positions between Ö and 11.5 degrees, the distance from the pt-K curve to the central axis of the axis 38 is smaller than the radius R2. However, this fact has little effect, since it only touches the intermediate diameter of the pipe at points between the original diameter and the reduced diameter reached last. In any case, the final diameter of the pipe is not affected.

Heim draft of the leveraged animal relations to the relief of the

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Drops from the pressing pressure at the end of each mibes is too "Note that the pipe can be continued in the longitudinal direction and rotated at the appropriate reversal points of a stroke when the distance from the central axis of the axis to the axis of the lower link lever is less than the distance from the central axis of the axis to the corresponding point of the pt curve. In the example explained above, the The dies run through an arc of 26 degrees, the pressing pressure being released when the dies are each over the Ends of the 23 degree arc are moved out to a suitable gap of about 3 »2 mm in that To create the present example for an axial movement and for a rotary movement of the pipe. Otherwise For example, dies 98 and 126 may be machined to provide relief at the end of each stroke for advancement and rotation of the tube by the ends of die recesses 100 and 128 slightly be beveled.

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Claims (1)

M 00960 Claims .) Machine for cold forming of pipes to smaller ones Diameter, characterized in that a frame (22), a pair arranged opposite one another Die holder (84, 130) with opposing curved shaped surfaces (100, 128), cooperating Dies (98, 126) that are held by the die holders (84, 130), an articulated connection between the upper die holder (84) and an upper component (36) of the frame (22), an articulated Connection between the lower die holder (130) and a lower component (28) of the frame (22) and drive members (224, 226, 228, etc.) for reciprocating movement of the die holders (94, 130) are provided, the mold surfaces (100, 128) of the die holder (84, 130) along a straight line during the back and forth Keep moving together " 2.) forming machine for tubes according to claim 1, marked 109827/0253 characterized by connecting links (90, 92) on each of the two die holders (84, 130), which thereby come into engagement with each other for coordinated movement of the two die holders (84, 130) during the reciprocating stroke movement 3) Timform machine for pipes according to claim 2, ^ denotes further connecting links (9 ^) carried by the frame (30) and are to be brought into engagement with one of the coordinating links (90, 92), the possibility of sliding movement of the two die holders (84, I30) with reference to largely switch off the frame (22). 4 «) forming machine for pipes according to claim 2 or 3, characterized by curved tooth-P segments GO, 92), each of one of the Die holders (84, 130) are carried and are engaged with each other to co-ox'dinate the movement of the die holders (84, 130). 5) forming machine for Kohre according to claim 4, 10 9 8 27/0253 BATH ORIGINAL is characterized by a rack (.94 ·) ϊ which is carried by the frame (30) and with the curved tooth segments (90, 92) is engaged to the possibility of sliding movement of the die holder (84, 13ü) opposite largely switch off the frame (50, 22). 6.) forming machine for drilling according to one or more of the preceding claims, characterized in that the drive device of the die holder (84, 130) drive members (224, 226, 228 etc.) for moving one of the die holders (84, 130) back and forth and links (198, 202, 206) interconnecting the die holders (84, 130) to cause one die holder (130) to drive the other die holder (84). 7.) Forming machine for tubes according to claim 6, characterized in that the connecting members (198, 2u2, 206, etc.) between the tool holders (84, 13o ) contain a slide (206) which can be moved in a Kiohtung , 109827/0213 which lies parallel to the line along which the mold surfaces (100, 128) of the die holders stay together, and levers (198, 2u2, 204, 216, 218) for a connection of the Gesenkhajfer (84, 130) are arranged with the carriage (206). 8.) Forming machine for Kohre. according to one or more of the preceding claims, characterized in that the articulated connecting links which connect the upper countersink holder (84) with the upper .bauteil (36) of the frame (22), comprise a connecting lever (56) which on the one hand to the upper die holder (84) and on the other hand to the upper Component (36) of the frame (22; is articulated, and the connecting members for an articulated connection between the lower (iesenkhalter (84) and the lower component (28)) dea frame (22) contain a second connecting lever (148) which on the one hand to the lower die holder (130 ') and on the other hand to the lower component (28) of the frame (22) is hinged. 9.) Forming machine for tube after one or 109827/0253 BATH ORIGINAL several of the preceding claims, characterized in that an upper actuating lever (198) is provided which is articulated to both projections (200, 82) of the upper connecting lever (56) intended for an articulated connection and which extends downwards in the direction of the upper Die holder (84) extends towards, also a lower operating lever (218) is arranged, which is hingedly coupled to the two projections intended for an articulated connection of the lower connecting lever C148) and extends upwards towards the lower die holder (150) , the connecting links (2o2, 206, 216) are connected to both upper and lower operating levers (198, 218) in order to bring about a coordinated movement between the operating levers (16, 198, 218) and the die holders (84, 130), and the Drive device for reciprocating movement of the die holders (84, 130), levers (224, 226) for driving one of the die holders (84, 1307) en. 109827/0253 If 1o.) UmformjaascMa · for drilling according to one or more of the preceding claims, characterized in that the connecting members for the actuating lever (198, 218) have a slide (206), _{guide members (208 f} 212) for sliding support of the slide (206) « Along the path parallel to the straight line and include levers (204, 202 and 216, respectively) connecting the carriage (206) to each of the actuating levers (198, 218), 11.) Forming machine for tubes according to one or more of the preceding claims 1 to 10, characterized in that the drive device for one of the die holders (84, 1JO) includes an arm (224) which is attached to one of the two die holders (84, 130) is attached, a crank arm (226) which is articulated with the Arm (224) is connected, and drive members (238, 236, 232,230, 228) for driving the Crank arm (226). 12.) Forming machine according to one or more of the preceding claims 1 to 11, characterized in that 109827/0253 BATH ORIGINAL tJ indicates that the lower die holder (130) contains two spaced apart cam control rollers (186, 188) and cam plates (194 · »196) carried by the frame (3o) for engagement with the cam steaer rollers (186, 188) and for assistance in holding the lower die holder (130) at certain points m every stroke of movement. 13.) Forming machine for carrots according to one or more of claims 1 to 12, characterized in that a fixed frame (22), a pair of opposing die holders (84, 130) and one of the two die holders supported pair of dies (98, 126) are provided, a connecting lever (56) with the upper die holder (84) on the one hand and with an upper component (36) of the stationary Frame (22) is articulated to support the upper die holder (84) and its die (98) through the upper member (36) of the frame (22), the connecting lever (56) the center of its articulated connection with the upper die holder (84) 109827/0253 along an arched path that leads in essentially lies on part of a pt curve that is off the central axis of the rotary motion is described when the surface (100) of the upper die holder (84) is longitudinal is moved in a straight line, a second connecting lever (148) on the one hand articulated with the lower die holder (130) and on the other hand with a lower component (28) of the frame (22) is articulated to hold the lower die holder (130) and its Die (126) through the lower component (28) of the frame (22), the second connecting lever (148) the center of the articulated connection with the lower die holder (130) lengthways an arcuate path which lies essentially on part of a pt curve which is described by the steering center if the surface (128) of the lower die holder (130) is moved along a straight line, and connecting members (90, 92) are provided which are supported by the die holders (84, 130) and are in engagement with one another to permit movement of the die holders (84, 130) and the dies (98, 126) coordinate. 109827/0253 14.) forming machine for tubes according to claim 13, characterized by an upper operating lever (198) connected to the upper connecting lever (56) is movable, and by a lower operating lever (218), the is movable with the lower link lever (148), as well as by connecting links (202, 206, 216), which establish a connection between the two actuating levers (198, 218) to lead. 15) forming machine for tubes according to claim 13, characterized by cam plates (1 ^> 4, 196), attached to the frame (22) and by cam control rollers (186, 188) driven by the lower die holder (130) are carried for engagement with the cam plates (194, 196) during part of the movement of the Λ lower die holder (13o). 16.) Forming machine according to one or more of the Claims 1 to 15, characterized in that the radii (R) of the molding surfaces (100, 128) of the upper and lower die holders, the distance between the mold surfaces and 109827/0253 exceed the articulated connections of the lever (56) and the frame * 17 ·) Forming machine for tubes according to one or more of the preceding claims 1 to 16, characterized in that each of the die holders (84, 150) has a groove (96) for Receiving a die (98) with beveled end faces, a wedge (112, 114) each end of the die (96) engaged with that die and with Screws (108, 110) for an adjustable connection between the wedges (112, 114) and the die holder (84), whereby the wedges (112, 114) relative to the die holder (84) can be moved back and forth to the die (98) in iiängsrichtung of the die holder in a predetermined position opposite the counterbore holder (84). 109827/0253