AU600070B2

AU600070B2 - Method for forming a screw thread and tubular body with a screw thread

Info

Publication number: AU600070B2
Application number: AU10246/88A
Authority: AU
Inventors: Heinz Gruber
Original assignee: Gd Anker & Co KG GmbH
Current assignee: GD-ANKER GmbH
Priority date: 1987-01-13
Filing date: 1988-01-13
Publication date: 1990-08-02
Anticipated expiration: 2008-01-13
Also published as: JPH069719B2; ES2041259T3; ATE90891T1; EP0274719A2; CA1333652C; EP0274719B1; AU1024688A; EP0274719A3; JPS63180334A; DE3700758C2; DE3700758A1

Abstract

The production of the internal thread of a connection sleeve (4), which is used as a coupling element for parts of a rock support or of a drill rod, by machine-forming, in particular by thread-cutting, entails great effort since, in the round thread used here, a considerable amount of machining work is required. Furthermore, it is disadvantageous in this application in the machining of the thread that the long-term strength of the connection sleeve is considerably impaired due to the notch effect in the base region of the thread turns. A connection sleeve and a method for its production are proposed, in which the internal thread is produced without machining by shaping the outside of the connection sleeve (4) in the manner of a thread so that the image of this shaping forms the internal thread to be produced on the inside. Apart from the increase in strength caused by the non-cutting shaping, which is usually cold shaping, due to material reinforcement, the further advantage results that the shaping required here can be applied in a single operation so that the production costs of connection sleeves (4) of this type can be reduced. Furthermore, it is advantageous that the external thread, interacting with the internal thread of the connection sleeve, of the components to be connected to one another can have a basic shape which corresponds to the outside thread-type shaping of the connection sleeve (4). <IMAGE>

Description

6 OO7Q COMMONWEALTH OF AUSTRALIA Patents Act 1952 C O M P L E T E S P E. C I F T I O N

(ORIGINAL)

Application Number Lodged Complete Specification Lodged Accepted Published Priority Related Art This document contains ith amendmenlts made unsr Section 49 and is correct for printing.

13 January 1987

I

o GO a -0 Name of Applicant GD-ANKER GMBH Address of Applicant Am Schlorbach 17, D-3370 Seesen/Rhuden Federal Republic of Germany Actual Inventor/s Heinz GRUBER Address for Service F.B. RICE CO., Patent Attorneys, 28A Montague Street, Balmain N.S.W. 2041 Complete Specification for the invention entitled: METHOD FOR FORMING A SCREW THREAD AND TUBULAR BODY WITH A SCREW

THREAD

The following statement is a full description of this invention including the best method of performing it known to us:t *175 Qttt 5 o sos 0*70 0 o *0 o 0 0 a40 0 o **a Se 080 S -2- The invention relates to a method for the cuttingless shaping of a screw thread on a tubular body.

It is customary to connect together the extension rods of rock anchors, drilling rods and the like with screw connections. For this, the two juxtaposed drilling rod or rock anchor parts to be connected together have an external thread and are connected by means of a connecting sleeve having a corresponding internal thread. Especially with drilling rods, these thread sections serve simultaneously as coupling regions for coupling up a rock hammer or other driving apparatus. In order to enable easy handling of these threaded connections in view of the high loads which apply and also with heavy soiling, it is usual to make use of a round thread or an approximately round thread.

It is known to manufacture an internal thread of such connecting sleeves by a cutting process, particularly by screw thread cutters and so on. Not only is the extent of the amount of cutting involved a disadvantage, but so also 20 is the transverse weakening of the sleeve caused by the volume of material cut away as well as the notching effect involved in the cutting, particularly at the bottom of the separate thread turns, by which the durability of the sleeve is adversely affected.

It is therefore the purpose of the invention to conceive a method for the cuttingless forming of a screw thread and a tubular body carrying a screw thread, which is easy to carry out or manufacture, is particularly connected with low manufacturing costs and enables the preparation of a screw connection ensuring high strength.

In one aspect therefore the present invention comprises a method for the cuttingless shaping of a screw thread of an internal surface of a tubular cylindrical body member, in particular a sleeve, without the use of an internal support or die tool, characterised in that III_1~-~ i 3 0 00 0000( c 0 0000 00 Q 0 0 0 0 0(, 0000 0 0000 000 00 00 0000 .00,00

S

0000 00 0~ 0 000 0 0 000 00 so0 0 0 threaded turns are formed on an external surface of the body member, a copy of which, arising by corresponding deformation of the internal surface, produces a desired internal screw thread.

It is essential to the invention that, with a known cuttingless forming process, the screw thread to be made is formed directly by a shaping tool engaging a side of the tubular basic article, since this formation applies in, for instance, an external shaping contact to the resultant internal formation. In the manufacture of a sleeve, thus a start can be made from a smooth tubular work-piece, which by external forming receives an internal screw-thread, the profile of which is then annealed to a round thread. The measurements of the original 15 smooth-walled starting member are dimensioned in dependence upon the measurements of the counter-thread to which the sleeve is to be screwed, so that a minimum clearance is given between the threaded turns when brought into engagement with one another. It is of particular 20 advantage that the internal thread formed in this way can be made in a single forming step. In comparison to a screw-cutting process the manufacturing costs of a sleeve provided with an internal thread are considerably reduced.

A further aspect of the present invention includes that the screw thread is formed on the internal surface of the body member and that the threaded turns in the external surface, are preferably formed by means of cold deformation by rolling, flattening, pressing or the like.

Fundamentally, all cuttingless forming methods can be used in the manufacture, including hot forming and also cold forming methods. It is particularly advantageous, especially in view of the low tolerances to be achieved as well as the strength of the work-piece connected with the shaping, to use a cold forming method.

35 Another aspect of the invention includes that hi

'E

I

0 -4the basic shape of the screw-thread profile formed by the threaded turns of the internal surface or the external surface of the body member is used as a counter profile for a screw connection. This brings the advantage that the same method of operation can be used both for the manufacture of the internal thread and also for the manufacture of the external thread co-operating with it, where merely the shaping tool must be somewhat adapted for the purposes of adapting to the curved screw thread flanks of the internal thread, as well as for establishing the necessary clearance between the internal and external threads.

The method according to the present invention is particularly advantageous in the manufacture of connecting sleeves which are used in the coupling of extension rods to a rock anchor, a drilling rod or the like. In these cases characterised by an extremely high mechanical loading, it is particularly effective that the connecting sleeve is strengthened by the proposed shaping process and consequently achieves a high strength. Also in these cases of use because of the heavy soiling to be expected, a rounded thread or a similar type of thread is preferred, in order to ensure satisfactory handling in the extreme conditions of use. Since the method of manufacture according to the invention is connected with a flow of the material, it is naturally limited without reference to the actual shaping contour to the manufacture of such types of screw-thread in which no sharply angled edges are to be made, as occurs for example with a metric screw thread. Preferably in the case of drilling rods, the whole outer contour including that of the connecting sleeve, is provided with thread formations, so that with narrow bore-holes the external guidance or discharge of drilling fines is facilitated.

i-7 It is very advantageous to use the method according to the invention in the manufacture of connecting sleeves which are inserted into channel struts which includes the use of a tubular body in a threaded connection between two cylindrical particularly tubular components, especially threaded spindles of a channel strut, where end sections of the threaded spindles to be connected together have an external screw thread, whose threaded profile corresponds to the basic form of the external screw-thread-like deformation made on the tubular body forming a connecting sleeve. It is particularly advantageous in this connection that the connecting sleeves according to the invention can be constructed to any length in practice.

Together with good guidance of the threaded spindles, a most satisfactory constructional shape is also given.

The purpose explained at the beginning, insofar as it relates to a tubular body provided with a thread as well lift as a threaded connection as such, is solved by a tubular body according to the invention as well as a threaded connection according to the invention.

The invention is more closely described in the *r $1 4I following with reference to the embodiment of a threaded connection illustrated in the drawings. These show: Fig. 1 a partial view of a rock anchor 25 simultaneously used as a drilling rod; Fig. 2 an enlarged view in elevation of a connecting sleeve according to the invention; Ia 0.

Fig. 3 a sectional illustration of the connecting S sleeve according to Fig. 2 in a section plane III-III; Fig. 4 a diagrammatic threaded connection according to the invention representing one section; Fig. 5 a connecting sleeve according to the invention intended for use with a double-sided channel strut.

6 The bore-hole-side end part of a rock anchor is indicated with 1 in Fig. 1, which is also used as a drilling rod. This end part 1 is a tubular body, which carries a known drill head 2 on its end remote from the drill base. The drill head 2 is provided with a central bore in a manner not shown in the drawing, which serves to guide a drilling medium. This bore is in communication with the internal space of the end part i.

The end part or tubular body 1 has a threaded section 3, which is connected by means of a connecting sleeve 4 to an extension rod 5. The extension rod 5 carries a threaded section 6. The extension rod 5 is generally constructed as a tubular body like the end part i.

o Basically, several of such extension rods 5 can be 001t0 a 15 connected together and thus the total length of the rock anchor can be adapted to existing requirements over wide limits. Also, the showing of the section of the preceding oro rock anchor located in the region of the bore-hole-side end, to which a drilling hammer or other driving device is coupled during the drilling operation, has been omitted for reasons of clarity in the drawing.

0 00s The screw-thread sections 3, 6 illustrated as °0 external threads on the tubular bodies 1, 5 as well as the 0 00 internal thread of the connecting sleeve 4, (not shown in 25 Fig. 1) are made as approximately round threads in the embodiment shown, which facilitates trouble-free handling despite the heavy soiling arising during the drilling o0 0 operation. According to the invention, the internal 000.. thread of the connecting sleeve 4 is made by a cuttingless 0 shaping, here by a cold-forming operation, in which the connecting sleeve 4 is given the profile shown in Fig. 1, by means of a forming tool on the outside 7, where the internal thread is formed by internally effective displacement of the material complementary to the external profile. Further reference is made to this below in relation to Figs. 2 to 7 4. As the view of a connecting sleeve 4 shown in Fig. 2 indicates, the outside 7 consists of a helically-shaped wound deformation 8 of approximately arcuate shape in cross-section, where between the separate shaped turns 8, smooth land surface sections 9, which are only slightly deformed, remain.

Fig. 3 indicates that, by the shaping process of the present invention the inside of the threaded sleeve screw-threaded turns 11 are formed whose cross-sectional shape match essentially with the circular arcs 8 and which can thus be regarded as rounded threads. These thread turns 11 lie directly opposite the formations 8. It is preferable for the article of invention that the formation of these internal threaded turns 11 is controlled at least accurately enough, both as regards the depth of the threads and also in relation to the pitch, by the externally-effective deformation, that the threaded turns 11 can function as internal threads with relation to a given external thread, which in the present case is formed by the threaded sections 3, 6 (see Fig. 1).

Fig. 4 shows the effective pairing of the turns of the internal threads of the connecting sleeve 4 on the one hand and the external threads of the threaded section 3 on the other hand. The threaded sections 3, 6 are likewise made by a cold forming process and consequently exhibit a profile which corresponds qualitatively to that of the external part 7 of the connecting sleeve 4 (see Fig. 1).

The invention is not limited to its use with connecting sleeves for rock anchors. Fundamentally, it can find use with advantage in all cases in which a tubular body is to be provided internally with a round thread or a comparable screw thread.

In Fig. 5, an embodiment of a connecting sleeve 4 is shown, which can be used with a two-sided channel strut formation and is consequently provided with two different, I MPW_ 8 namely counter-handed, threaded sections 12, 13. In the end regions of this connecting sleeve, 4 threaded spindles can be inserted, which serve in known manner for supporting the channel walls of an excavation. These threaded spindles have an external profile which corresponds essentially to that of the tubular bodies 1, of Fig. 1, where these threaded spindles are not represented for reasons of simplicity in the drawing. In order to carry out, by a relative rotation of the connecting sleeve 4 with respect to the threaded spindles, removal of the latter or their contact with the channel walls which are to be supported, the connecting sleeve 4 is provided, in a way likewise not shown in the drawing, with means for initiating a turning movement. In the simplest case, this auxiliary device can be a hole in which a lever can be inserted. Also a nut or a shaped tube can be welded to the connecting sleeve 4, which serves to allow a turning movement in connection with a corresponding tool. If required, a plastics nut can be cast or pressed into the exterior of the connecting sleeve 4.

Since the connecting sleeve 4 with the internal thread made according to the invention can be made to any practical length, a particularly reliable connecting sleeve which improves the resistance to bending of threaded spindles of channel struts is given.

Simultaneously, in this way the separate parts of the channel struts can be made relatively small by reason of the length of the connecting sleeve.

Claims

2. A method according to claim i, characterised in that r, the threaded turns in the external surface are preferably formed by means of cold deformation by rolling, flattening, pressing or the like. t t t S3. A method according to claim 1 or 2, characterised in °t,9 that the basic shape of the screw-thread profile formed by the threaded turns of the internal surface or the external surface of the body member is used as a counter profile for a screw connection.
4. Tubular body with internal threads in the form of an #Qa0 aoo approximately round screw-thread formed by the method of o claim i, characterised in that the threads are a copy of an external screw-thread-like cold-deformation. ao 5. Tubular body according to claim 4, characterised in that opposite-handed threads are formed in the connecting sleeve running from the ends, which extend preferably to o. the middle of the connecting sleeve.
6. Tubular body with external threads in the form of an approximately round screw-thread formed by the method of claim i, characterised in that the external threads are the copy of an internal screw-thread-like cold-deformation.
7. Use of a tubular body according to claim 4 in a screw-threaded connection between two cylindrical and especially tubular components, for instance, parts of a rock anchor, a drilling rod or the like, whereby end sections of the components to be connected together have an external thread, whose threaded profile corresponds to a basic form of the external screw-thread-like deformation made on the tubular body forming a threaded sleeve.
8. Use of a tubular body according to claims 4 and 5 in a threaded connection between two cylindrical particularly tubular components, especially threaded spindles of a channel strut, where end sections of the threaded spindles to be connected together have an external screw thread, whose threaded profile corresponds to the basic form of the external screw-thread-like deformation made on the tubular body forming a connecting sleeve.
9. A method for the cuttingless shaping of a screw thread substantially as hereinbefore described with reference to the accompanying drawings. A tubular body substantially as hereinbefore described with reference to the accompanying drawings. DATED this 15 day of May 1990 GD-ANKER GmbH Patent Attorneys for the Hp Applicant: F.B. RICE CO. i