DE3728886A1 - Means for securing a pipe connection against torsional forces, and process for producing pipe-connection pieces which are secured against torsion - Google Patents

Abstract

Pipe connections comprising pipes of different degrees of material hardness, which are plugged together telescopically at the connection point and are produced by means of a pressed-on clamping ring, are indeed resistant with respect to loading by tension, compression and vibration, but they are susceptible with respect to torsional forces. In order to secure against torsional forces, the end of the interior pipe consisting of the harder material is provided, on the outer side, with a grooved arrangement, the telescopically plugged-together region of the connection being lengthened by approximately 50%. In addition to the clamping ring, a securing ring, having a slightly smaller internal diameter than that of the clamping ring, is pressed onto the pipe connection over the region of the grooved arrangement, the securing ring being only approximately half as long as the clamping ring. The process exhibits the individual manufacturing stations for producing pipe-connection pieces according to the invention.

Description

The invention relates to a device and a Ver drive to create a backup of a pipe connection against torsional forces.

It is known to make permanent pipe connections in which the pipes, especially those from differ Chen materials, telescopically at the connection point be put together and then by sliding one Clamping ring made of metal pressed onto this area will. The clamping ring then remains under tension in the elas table area. Such compounds are known from the European patent application 00 48 003 and from OS 2 70 056 as well as the publications cited there.

The pipe connections considered here are as the applicant's longstanding practice has shown, except neatly resistant to tensile and compressive loads forces, as well as by vibration. The strength against gate However, there is only a certain amount of force, especially with connections of a single pipe string, not always sufficient so that the connection by suitable measures, e.g. Brackets or Pipe clamps to prevent unintentional twisting when handling must be secured. Especially when connecting Cu Pipes with those made of A1 in diameter ranges under 20 mm, as they occur in large numbers in the refrigeration industry  this problem on. Are the individual parts of a refrigeration cycle running, which have been put together by means of clamping ring connections are, e.g. B. once in a refrigerator or a freezer mounted, there are hardly any torsional forces on the pipe joint can work. The situation is completely different if e.g. to the aluminum evaporator of a refrigerator or chest a copper pipe ver on the aluminum suction pipe section on the evaporator Extension by means of a clamping ring is to be attached to the connection manufacture with the encapsulated motor compressor by brazing to be able to.

As a rule, thousands of such aluminum evaporators with Al-Cu suction lines are to be transported from the place where the evaporator is manufactured to the assembly line for the cooling unit or to the final assembly of the cooling unit in large-scale production. In this way, the evaporators with the Al-Cu suction lines must be treated like "raw eggs" in order not to cause any leaks when handling and bending the pipes. In OS 27 00 516 (see. Fig. 12 to 17 and the associated part of the description) a torsion protection for a clamping ring connection has already been described. However, the construction shown there is so complex that it is not used in large-scale production of the refrigeration technology sector mentioned here for cost reasons.

The present invention is based on the object simple and cheap "single ring connections" (cf. Vulkan-Lok ring brochure, publication no. 0884 LOK / l, pages 3, 4 and 6) secure enough against torsional forces without the cost too much due to construction elements that are difficult to manufacture increase. According to the invention, this is done in that

• 1. the length of the telescopically assembled part the pipe connection is larger than for normal nor Male ring connection necessary, preferably 50% greater.
• 2. the end of the inner, from the harder work  fabric existing pipe over a length of at most corresponds to the pipe diameter on the outside is provided with a longitudinal corrugation.
• 3. in addition to the clamping ring, another clamping ring, in The following circlip called, with a slight Smaller diameter than the 1st clamping ring preferably up to the stop on the clamping ring of the Is pressed on the opposite side, such that the Si circlip the corrugated area inside the Connection covered.

The locking ring is preferably only half as long as the clamping ring of the pipe connection.

The two inner edges of the circlip are the same rounded or beveled in contrast to the speci ellen shaping of the inside of the clamping rings, which the Carry out the actual pipe connection. This design the circlip has the advantage that this before Postponement should not be brought into a certain position The inner wall of the circlip can be cylindrical without Projections or Konitität be formed.

Another variant of locking a clamping ring connection against torsional forces can according to the invention also consist in that the clamping ring itself preferably by 50% extended on the side of the larger inner diameter is such that the area of extension extends beyond the area the corrugation of the inner tube is sufficient. This variant requires a modification of the normal clamping ring of a single ring Ver binding while using an additional fuse The standard clamping rings can be used and just an easy to manufacture circlip is required, its assembly is only a simple additional Machine element requires. However, both variants are essential Lich less expensive than the type of anti-rotation device, as shown for example in OS 27 00 516.  

Often used in the manufacture of aluminum evaporators far away for refrigerators and the like also prefabricated copper-aluminum Large numbers of mini pipe pieces are required as connecting pieces whose aluminum end is welded with an aluminum evaporator and its Cu end with a suction line to the compressor is soldered. Such connectors must depend on the type of processing, especially against torsional forces be secured. The backup of the Pipe connection according to the invention in particular, because then an automatic production of these pipe connectors, the z. b. can consist of pipe pieces of approx. 200 mm length, can be carried out.

To do this, one side of the manufacturing facility the copper pipes are automatically cut, straightened, deburred and passed on. Next to it, on the other side of manufacturing there is an identical operation for the Al pipes. Then the Cu pipe end is on the side of the Pipe connection calibrated and in the same operation with the outer corrugation. The parallel next to the Cu-Roren Al pipes running through the plant are used simultaneously calibrated and expanded the copper tubes in one operation. Both pipe sections are before the described operations held by automatically controlled clamping heads. In the next Most station, the clamping ring on the Cu pipe is in the correct position Location and on the Al tube of the circlip and up pushed to the clamping heads. Be in the next station the clamping heads loosened and swiveled after new ones Clamping heads the pipes close to those abge from the junction have gripped pipe ends. This is necessary so Clamping ring and circlip unimpeded by the first Clamping heads are brought into the required end position can. Then the two pipe sections become telescopic put together like a steel bolt through the aluminum tube with a slightly conical tip (taper approx. 1 ° to 2 °) introduced such that the conical tip inside the corrugated area of the Cu pipe. When this has happened  clamp ring and circlip are each by a claw in opposite directions until they touch each other on the telescope Properly put together pushed area. The support of the copper pipe in the area of the corrugation by the steel bolt allows a particularly good pressing of the softer pipe works into the grooves of the corrugation.

Even if an extended clamping ring for connection and simultaneous fuse is used, the steel bolt, as described above, before sliding the extended Clamping ring introduced. The steel bolt will be finished the connection is withdrawn and the finished pipe joint pieces of equipment leave the production facility and its operation can run completely automatically.

In the drawings are the securing of pipe connections against torsional forces according to the invention and the method for the production of torsionally secured pipe Connectors shown schematically and then explained.

Fig. 1 shows a still open clamping ring pipe connection in single ring design with additional locking ring, the locking ring and the locking ring in view and section, and a frontal partial view of the Rif felung.

FIG. 2 shows the closed pipe connection from FIG. 1.

Fig. 3 shows a closed clamping ring pipe connection in single ring design with an extended ring, and the extended ring in view and section.

FIGS. 4 to 9 show the stages of an automatic manufacturing apparatus for compression-Rohrverbinduns pieces with Torsionssicherung according to the invention.

As an example, as shown in FIGS. 1 and 2, a Cu tube ( 1 ) and an Al tube ( 2 ) are to be connected. First, the end of the copper pipe is calibrated with an appropriately designed calibration tool and provided with a fine, axially parallel corrugation over a length that corresponds approximately to the pipe diameter (3), the depth of which can be up to 2/10 mm depending on the pipe wall thickness. The shape of the webs is preferably triangular with the tip pointing outwards ( 3 a ). Depending on the diameter, the Al tube is expanded so that the end of the Cu tube can be pushed telescopically into the expanded area ( 4 ) of the Al tube ( 2 ) as far as it will go, so that the corrugated end of the tube ( 1 ) on inner end of the expansion of tube ( 2 ) is ( 3 a ). The clamping ring ( 5 ), with the rounded inner diameter ( 5 a ) directed towards the pipe end, is placed on the gu pipe ( 1 ), while the locking ring ( 6 ) is placed on the Al pipe ( 2 ) before it expands becomes. It does not matter whether the rounding ( 6 a ) or ( 6 b ) points towards the pipe end. The clamping ring ( 5 ) and the locking ring ( 6 ) are then pressed over the plugged pipe ends, as can be seen in Fig. 2 below. Since the inner diameter of the locking ring ( 6 ) is slightly smaller (preferably up to 0.2 mm depending on the tube diameter) than that of the clamping ring ( 5 ), a particularly intimate compression between the inside takes place in the corrugated area ( 3 ) of the copper tube wall of the Al tube and the corrugated area of the Cu tube, aluminum material being pressed into the grooves of the corrugation.

In the connection according to FIG. 3, the compression between Cu and Al is not as intense but still sufficient because the prolonged ring (7) in the end region, the clothing over the corrugating takes the tube (1) to lie, no smaller internal can get diameter because of the sliding direction of the ring when pressed. A slightly increased wall thickness or material hardness of the Cu pipe is advantageous in this case.

FIGS. 3 to 8 relate to a process for the preparation of position according to the invention torsionsgesicherten pipe sections, here for example consisting of a copper pipe of 8 mm in outer diameter and 0.5 mm wall thickness. Both pieces of pipe should be 200 mm long. In the individual production stations, the work steps are only shown schematically. These stations can be constructed from elements which are known per se, but which are modified accordingly to the task at hand here. The individual stations are expediently assembled to form a compact production unit which is operated by means of compressed air or hydraulics or with a mixture of the two. In the station Fig. 4, both the Cu tube ( 1 ) and the Al tube ( 2 ) are unwound from the roll, straightened ( 8 a ) and at ( 8 b ) in a known manner by rolling off and automatically onto the desired length separated. A transport device ( 9 a ), ( 9 b ) picks up the pipe sections and directs them according to the type of pipe, running in parallel next to each other to the next station Fig. 5. In the following, transport and transfer devices between the individual stations are no longer mentioned. In the station Fig. 5, the pipe sections ( 1 ) and ( 2 ) with clamping heads ( 10 ) and ( 11 ) are gripped so that the Cu pipe protrudes enough far over the clamping head to make it about 3 To be able to calibrate pipe diameters (e.g. to 7.8 mm OD and 7.0 mm ID), whereby the pipe end receives the corrugation ( 3 ) at the same time. This is done with a calibration head, which is indicated by ( 12 ) and which is pressed as far as it will go on the end of tube ( 1 ) and then pulled back again. Simultaneously with pipe ( 1 ), the adjacent Al pipe ( 2 ) with the clamping head ( 11 ) is also held in such a way that the pipe end can receive the widening ( 4 ) with a stamp ( 13 ). If space is required, the pipes ( 1 ) and ( 2 ) can be guided in the station so that they are offset in the axial direction. In the station Fig. 6 are from the non-processed pipe ends thereof, the clamping ring (5) and the retaining ring (6) from a magazine with shaker via a feed device in each case up to the clamping heads (10) and (11) to the tubes (1) or ( 2 ) pushed. Here, z. B. with an opto-electronic device to ensure that the clamping rings ( 5 ) are always pushed on with the side of the larger inner diameter first. In the station Fig. 7, the pipes with new clamping heads ( 14 ) for the pipes ( 1 ) and ( 15 ) for the pipes ( 2 ) are gripped, at the same time the clamping heads ( 10 ) and ( 11 ) loosened and pivoted. The new clamping heads are closer to the unprocessed end of the tubes ( 1 ) and ( 2 ) on the other side of the clamping ring ( 5 ) and locking ring ( 6 ), so in station Fig. 8, in which the tubes ( 1 ) and ( 2 ) are put together telescopically, the clamping ring ( 5 ) and the locking ring ( 6 ) can be brought into the end position by means of the claws ( 16 ) and ( 20 ) of a pressing device. Before that, however, a steel bolt ( 18 ), (in the example with an OD of approx. 6.9 mm), with a slightly conical end ( 19 ), the length of which is at least that of the corrugated area ( 3 ) of tube ( 1 ) with a taper of 1 ° to 2 ° (the surface of the bolt should be hard chrome-plated and polished or made of polished stainless steel) so far that it is inserted into the Al tube so that the conical end inside the corrugated area ( 3 ) of the tube ( 3 ) lies ( 19 a ). In the station Fig. 9, the claws ( 16 ) and ( 20 ) of the pressing device move back again, the clamping heads open, they swivel out and the finished pipe connection falls out of the machine.

By supporting the grooved area inside by means of a conical steel bolt, the pressing between Cu and Al particularly intense here. The slight taper the pin tip in the loaded area makes it easier to go back drive the bolt without material.

Claims (7)

1. Securing a clamping ring pipe connection from pipes of different material hardness against torsional forces, characterized by the following features:

• 1. The length of the telescopically assembled part of the pipe connection is greater than that required for a "single ring connection", preferably 50% larger.
• 2. The end of the inner tube made of the harder material is provided with a longitudinal corrugation on the outside over a length that corresponds at most to the tube diameter.
• 3. In addition to the clamping ring ( 5 ), a locking ring ( 6 ) with a slightly smaller, maximum 0.2 mm smaller inner diameter than with the clamping ring ( 5 ) is pressed onto the connection point in such a way that the locking ring ( 6 ) covers the corrugated area ( 3 ) of the harder tube ( 1 ) covers.
• 4. The locking ring ( 6 ) is preferably only half as long as the clamping ring ( 5 ).

2. Fuse according to claim 1, characterized in that both edges ( 6 a ) and ( 6 b ) on the inner diameter of the locking ring ( 6 ) are chamfered or rounded in the same way. 3. Fuse according to claims 1 and 2, characterized in that the inside of the locking ring ( 6 ) is cylindrical. 4. Fuse according to claims 1 to 3, characterized in that the retaining ring ( 6 ) is pressed onto the clamping ring ( 5 ) until it is in contact. 5. Fuse according to claim 1, characterized in that the clamping ring ( 5 ) is extended so far, preferably by 50%, that the extended ring part covers the corrugated area ( 3 ) of the harder tube ( 1 ). 6. Process for the production of clamping ring pipe connections from pipe pieces of different material hardness with protection against torsional forces according to claims 1 to 4, characterized by the following manufacturing steps:

• a) reeling the harder pipes ( 1 ) and the softer pipes ( 2 ) from the roll, going through a straightening section ( 8 a ) for both pipe types, their lengths, preferably with means of chip-free rolling ( 8 b ) and passing on the pipe pieces from both Materials on transport devices ( 9 a ) and ( 9 b ).
• b) clamping the opposing pipe sections ( 1 ) and ( 2 ) with clamping heads ( 10 ) and ( 11 ) in such a way that the ends of pipe ( 1 ) and ( 2 ) to be deformed protrude at least 3 pipe diameters from the clamping heads, calibrate and press the corrugation ( 3 ) at the ends of the tubes ( 1 ), as well as calibrate and widen the ends of the tubes ( 2 ).
• c) feeding the clamping rings ( 5 ) on the tubes ( 1 ) and the retaining rings ( 6 ) on the tubes ( 2 ) up to the clamping heads, the clamping rings z. B. be supplied by an opto-electronic device so that the clamping ring with the larger inner diameter is pushed forward.
• d) New clamping of the pipes ( 1 ) and ( 2 ) by means of clamping heads ( 14 ) and ( 15 ) on the other side of the rings pushed on, which are arranged near the rear pipe ends, and loosening and pivoting of the first clamping heads ( 10 ) and ( 11 ).
• e) telescopic assembly of the tubes ( 1 ) and ( 2 ), insertion of a steel bolt ( 18 ) with a slightly ko nical tip, taper preferably 1 ° to 2 °, through the tube ( 2 ), to the extent that the conical end inside of the corrugated area ( 3 ) of tube ( 1 ) is ( 19 a ), the conical tip having at least the length of the corrugation of tube ( 1 ). At the same time, the clamping ring ( 5 ) and the locking ring ( 6 ) are displaced in opposite directions by the claws ( 16 ) and ( 20 ) of a pressing device into the end position until the two rings touch each other. The steel bolt ( 18 ) is then pulled out of the tube 2 into its starting position.
• f) retracting the claws ( 16 ) and ( 20 ), opening and swiveling the clamping heads ( 14 ) and ( 15 ) and ejecting the finished pipe connection.

7. The method according to claim 5, characterized in that the manufacturing stations Fig. 4 to Fig. 9 are combined into a compact manufacturing unit, the operation of which runs automatically.