US3587294A

US3587294A - Rotary tube-testing presses

Info

Publication number: US3587294A
Application number: US810203A
Authority: US
Inventors: Erwin Kost
Original assignee: Schloemann AG
Current assignee: Schloemann AG
Priority date: 1968-04-09
Filing date: 1969-03-25
Publication date: 1971-06-28
Anticipated expiration: 1988-06-28
Also published as: GB1249921A; FR2005830A1; JPS4924313B1; ES365402A1; BE731181A; DE1773160B1; SE338181B; NL6903700A

Abstract

A TUBE-TESTING PRESS HAVING A MAIN DRIVING SHAFT JOURNALED AT ONE END IN A STATIONARY BOLSTER AND AT THE OTHER END IN AN AXIALLY MOVABLE BOLSTER, WITH TESTING-HEAD CARRIES SECURED THEREON, AND A NUMBER OF TESTING HEADS DISPLACEABLE OVER STATIONARY CAMS, AND SYMMETRICALLY ARRANGED AROUND THE DRIVING SHAFT AND ROTATING ABOUT THE LATTER, WITH SEALING AND CLAMPING DEVICES LOCATED IN THE PIPE-TESTING HEADS. A PRESSURE-RAISER WITH A DIFFERENTIAL PISTON-AND-CYLINDER UNIT IN THE MAIN DRIVING SHAFT PROVIDES HIGH-PRESSURE LIQUID FOR ONE CYLINDER SPACE, THE OTHER CYLINDER SPACE BEING IN COMMUNICATION WITH A SOURCE OF LOW PRESSURE, FOR RETURNING THE PISTON.

D R A W I N G

Description

United States Patent ROTARY TUBE-TESTING PRESSES 4 Claims, 2 Drawing Figs.

US. Cl 73/49.5 Int.Cl. G0ln 3/12 Field ofSearch 73/49.], 49.5, 49.6

References Cited UNITED STATES PATENTS 5/1967 Brauer 73/49.6X

l 13,ss7,294

FOREIGN PATENTS 946,668 8/1956 Germany 73/495 1,139,669 11/1962 Germany 73/495 Primary Examiner-L0uis R. Prince Assistant Examiner-William A. Henry, ll Attorney-Holman, Glascock, Downing and Seebold ABSTRACT: A tube-testing press having a main driving shaft journaled at one end in a stationary bolster and at the other end in an axially movable bolster, with testing-head carriers secured thereon, and a number of testing heads displaceable over stationary cams, and symmetrically arranged around the driving shaft and rotating about the latter, with sealing and clamping devices located in the pipe-testing heads. A pressure-raiser with a differential piston-and-cylinder unit in the main driving shaft provides high-pressure liquid for one cylinder space, the other cylinder space being'in communication with a source of low pressure, for returning the piston.

PATENTEU JUN28 1971 SHEET 1 OF 2 M 7 5 m0 VK W.

Mu-ok ROTARY TUBE-TESTING PRESSES This invention relates to a rotary tube-testing press for the continuous testing of tubes under very high internal pressures. The tube-testing press in this case consists of a stationary bolster arranged upon a base frame, an axially movable bolster, and a main driving shaft joumaled in the bolsters, with a number of tube-testing heads axially displaceable over stationary cams, and symmetrically arranged around the driving shaft and rotating about the latter, with sealing and clamping devices located in the pipe-testing heads. Furthermore there pertains to the tube-testing press a pressure-raiser with a differential piston for producing an extremely high pressure for the testing of the tubes and for the clamping and sealing of the same in the testing heads, as well as stationary filling liquid and primary pressure liquid connections to the rotating main driving shaft.

Usually the testing of tubes by the continuous method is carried out in rotating testing presses only up to a pressure of about 200 kp per square centimeter. The adoption of a higher pressure, with a continuously operating tubetesting press of the conventional kind, is prohibited on grounds of safety in operation, or would only be possible at the cost of very severe wear of sealing sleeves; for the high pressure would have to be produced outside the press, and passed into the revolving part of the press through a rotary joint, which of course is only practicable with great technical skill and corresponding cost, the question of safety in operation being in this case of particular importance.

Present-day requirements however also extend to testing pipes of relatively great strength, in which the elastic limit or yield point lies at 90 percent of the breaking strength, under correspondingly high pressures of more than 200 kp/cmi. A further requirement resides in the fact that even when adopting extremely high pressures, as large a number of tubes as possible must be tested per unit of time. This latter requirement again can only be fulfilled by a multiple testing press or by a continuously rotating testing press. Moreover the requirement for a corresponding visual inspection of the tube, during the testing of tubes of great strength, is greater than with ordinary tubes. This requirement is at present met by the continuously working tube-testing press, in which only one tube at a time is located in the testing region, and which furthermore, owing to its rotation about the main driving shaft, also ensures a better view of the underside of the tube.

The object of the present invention is therefore to provide an economically operating rotating tube-testing press, in which the requisite high pressures are produced within the rotating system in an intelligent and simple manner.

According to the invention this aim is attained by arranging a pressure-raiser centrally in the main driving shaft of the stationary bolster of the testing press, revolving with it, and passing the high-pressure testing medium inside the driving shaft and in stationary conduits to the testing heads, the piston of the pressure-raiser being returnable into its initial position by means of a pressure force.

Owing to the pressure-raiser being arranged in the revolving part of the tube-testing press, it is possible to supply the pressure medium, water for instance, to the primary pressure side, under a pressure up to 200 kp/cm. to the main driving shaft by way of stationary connections. The further transmission of the water from the stationary part of the press into the rotating part, is now effected under this pressure, which is controllable in an economical manner through the usual sealing sleeves. First, in the rotating part, the conversion up to the very high pressure or secondary pressure is effected without special sealing sleeves, with their inevitably short life, being required. The further transmission of the very high and/or secondary pressure inside the driving shaft thus complies with the requirements as regards safety in operation.

In order to return the piston of the pressure-raiser into its initial position again, after releasing the pressure of the tubes, in a further development of the invention, the pressure force is provided by putting the cylinder space on one side of the piston into communication with a source of low pressure. In this case the filling water which is in any case available for filling the tubes to be between the rotating system of the testing presses, may for instance be employed in a simple manner for this purpose. A mechanical spring, on the other hand, has the disadvantage of a variable spring force conditioned by the stroke, as well as that restricted durability.

The differential piston of the pressure raiser is here supplied by primary-pressure liquid on one side of the piston and by filling-pressure liquid on the other side. Consequently the effective primary pressure upon the piston is the difference in pressure between the two pressure liquids.

According to a further feature of the invention, the pressure-raiser is only to be switched on by means of an electrical impulse controlled by the tube that is being tested. In this way it is ensured that the pressure-raiser operates only when a tube is present for testing.

Owing to the possibility of adopting even with rotating tubetesting presses, a very high pressure for tube-testing, one is in a position, as compared with the conventional but not rotating high-pressure testing presses, to attain an increase of from 30 to 40 percent in the number of tubes tested per unit of time. One thus has the possibility, even during the testing owing to the rotation of the tube, of being able to effect, a reasonably good visual examination of the underside of the tube.

One embodiment of the invention will now be described with reference to the accompanying drawings, in which:

HO. 1 is a side view of the tube-testing press as a whole; and

FIG. 2 shows on a larger scale a longitudinal section through a part of a stationary bolster, with a main driving shaft and a pressure-raiser.

FIG. 1 shows the stationary bolster or abutment 2 arranged upon a base frame 1, and an axially movable bolster or abutment 3.

The axial displacement of the bolster 3 is effected by means of a displacing motor 4, by way of a pinion 5, and a toothed rack 6 secured upon the base frame l. A main driving shaft 7, which is joumaled in the stationary bolster 2 and in the movable bolster 3 and also in bearing blocks 8, drives, from the stationary bolster 2, a testing-head carrier 9, and, by way of adjustable couplings 10, a testing-head carrier 11 mounted on the axially movable bolster 3.

In each of the testing-head carriers 9 and 11 are arranged symmetrically around the main driving shaft 7, a number of testing-head holders l2, movable axially and parallel to the main driving shaft 7, with testing heads 13 directed in each case towards the center of the press. At the other ends of the testing-head holders 12, namely the ends directed towards the

bolster

2 and 3, is arranged in each case a pair of rollers 14, in such a way that their axes are perpendicular to the axes of the testing-head holders. These pairs of rollers 14 roll upon and/or in stationary annular cams 15, arranged around the main driving shaft 7 on the

bolsters

2 and 3. These cams, drawn forward in their upper region and rearward in their lower region, effect the axial displacement of the testing heads 13.

Upon the main driving shaft 7 are also arranged a number of holding-tongs wheels 16, revolving with the shaft 7, for holding the tubes to be tested during the testing. On the displaceable bolster 3 the main driving shaft 7 is divided into a hollow shaft 7a and a solid shaft 7b, which are so connected with one another by means of key and keyway 17 as to be rotationally fast, but axially slidable one in the other.

To the bolster 2 is attached on the left a casing 18, for the accommodation of sliding electrodes for the transmission of electrical impulses to the rotatableportion of the press, as well as a rotating pressure-raising device 19, with a stationary outer filling-water connection 20, and a likewise stationary primary pressure-water connection 21, the casing 18, and a holding block 22 carrying the

water connections

20 and 21, and resting upon a girder 23, constructed as a cantilever or bracket and secured upon the base frame 1.

The main driving shaft 7 (see FIG. 2) is journaled in the bolster 2 in radial or self-aligning roller bearings 24. The rotation of the shaft 7 is effected by means of a drive, not shown, by way of a spur gear 26 secured upon it by means of a key and keyway 25. Upon the spur gear 26 is also provided a copyingmechanism drive 27.

into the left-hand end of the shaft 7 is screwed a hollow cylindrical externally offset screw-threaded insertion piece 28, upon the external thread 29 of which is secured a cylindrical hollow body 19a. The latter, together with a differential piston 30 sliding in it, forms the pressure-raising device 19. The piston rod 31 of the differential piston 30 slides in a bore 32 of the screw-threaded insertion piece 28. This bore 32 is continued with the same diameter into the left-hand end of the shaft 7, and is then extended axially through the shaft 7, and is then extended axially through the shaft 7, beyond the testinghead carrier 9 as a stationary conduit 33 with a smaller bore for the high-pressure or secondary-pressure water, to the testing heads 13.

To the left-hand offset end portion of the cylindrical hollow body 19a is attached an internally and externally tapering hollow cylindrical filling-water coupling piece 34, secured by means of a screw thread. Through the periphery of this coupling piece there passes a bore 35, with an externally arranged flange 36. From the latter a filling-water conduit 37 passes longitudinally around the outside of the pressure-raiser 19, and enters, by way of a further flange 38, through a bore 39 into the main driving shaft 7. Within the shaft 7 the filling water is supplied, by way of a longitudinal bore 40 to the testing heads 13.

From the filling-water conduit 37, likewise rotating with the main driving shaft 7, a branch 40a passes into an annular cavity 4], which is formed between the cylindrical hollow body 19a and the piston rod 31. The cavity 41 is therefore constantly subjected to filling-water pressure.

A stationary horizontal cylindrical tubular member 42 mounted upon the holding block or supporting casting 22 projects into the rotating hollow cylindrical filling-water connecting piece 34. Sealing sleeves 43 arranged between these two

members

34 and 42 are held by a stufling box 44. The filling water is admitted through the stationary outer filling-water connection 20 into the rotating filling-water connection 34, and passes, by way of the conduit 37, into the bore 40 of the main driving shaft 7. The primary pressure water is passed by way of the primary pressure-water connection 21, and, by way of a stationary cylindrical tubular member 45 arranged in the cylindrical filling-water connecting piece 345, into the rotating pressure-raising cylinder 19a. Between the pressure-raising cylinder 19a and the stationary tubular member 45, further sealing sleeves 46 are held by a stuffing box 47. The primary pressure water energizes the left-hand side of the differential piston 30. The right-hand side of the piston 30 is subject to filling-water pressure. The high-pressure or secondary-pressure water present in the bore 32 is forced by the piston rod 31 through the conduit 33, by way of inlet valves not represented, to the testing heads 13.

The differential piston 30 comprises a bush 48, upon the externally offset ends of which are likewise arranged sealing sleeves 49. A further longitudinal bore 50 arranged in the shaft 7 serves for the passage of cables from the sliding electrodes, located in the casing 18, to the testing heads 13.

lclaim:

l. A rotary tube-testing press for the continuous testing of tubes under very high internal pressures, comprising a base frame, a bolster mounted in a stationary position on the base frame, an axially movable bolster, a main driving shaft journaled in the bolsters, tube-testing heads arranged centrally around the driving shaft and rotating about the said shaft, stationary cams, the said tube-testing heads being axially displaceable over the said cams, sealing and clamping devices located in the tube-testing heads, a pressure-raiser, including a differential piston, for producing the very high pressure required for testing the tubes and for clamping and sealing the same in the tube-testing heads, the pressure-raiser being arranged centrally in the main driving shaft of the stationary bolster of the testing press and moving with it, stationary connections for admitting liquids at filling pressure and at a very high pressure to the rotating main driving shaft, stationary conduits inside the driving shaft for conveying the high-pressure liquid to the testing heads, and means for applying pressure to the piston of the pressure-raiser to return it to its initial position.

2. A rotary tube-testing press as claimed in claim 1, further comprising means for supplying high-pressure liquid to the cylinder space on one side of the piston, means for controlling the said supply of high-pressure liquid, and means placing the cylinder space on the other side of the piston in permanent communication with a source of low-pressure fluid, for providing the pressure force for returning the piston of the pressure-raiser into its initial position when the supply of high pressure liquid is shut off.

3. A rotary tube-testing press as claimed in claim 1, further comprising means for supplying high-pressure liquid to one side of the differential piston and filling-pressure liquid to the other side.

4. A rotary tube-testing press as claimed in claim 1, further comprising means for producing electrical impulses, and means for bringing the pressure-raiser into operation by means of these electrical impulses, under the control of a tube that is being tested.