GB2034224A

GB2034224A - Improvements in Push Benches

Info

Publication number: GB2034224A
Application number: GB7936120A
Authority: GB
Original assignee: Friedrich Kocks GmbH and Co
Current assignee: Friedrich Kocks GmbH and Co
Priority date: 1978-10-19
Filing date: 1979-10-18
Publication date: 1980-06-04
Also published as: FR2439049A1; GB2034224B; IT7949711A0; DE2845547A1; IT1118189B; FR2439049B1; DE2845547C2

Abstract

Guides (9) are provided at a feed table (3) of a push bench by which a mandrel rod (8) or a shaft rod pushes a pierced blank (6) through the push bench stands (1). The guides comprise upper and lower guide discs (10, 11) between which a guide opening for the pierced blank (6), the mandrel rod (8) and the shaft rod. By rotating the guide discs (10, 11) in timed relation to operation of the push bench, differing peripheral portions (12, 13, 14, 16) of the guide discs are brought into use to change the size of the guide opening in conformity with initial lateral introduction of a blank, feeding of the blank through the stands, and retraction of the mandrel and shaft rods the differing diameters of the pierced blank and the mandrel and shaft rods. <IMAGE>

Description

SPECIFICATION Improvements in Push Benches The invention relates to a push bench for the manufacture of seamless tubes, which push bench has a shaft rod, a mandrel rod and a feed table for pierced blanks to be deformed.

In known push benches of this type, there are no guides in the region of the feedtable, apart from shallow, groove-like surfaces on the feed table for receiving the pierced blanks. These groove-like surfaces are not able to prevent the pierced blank and the shaft rod or the mandrel rod from veering off or buckling in the region of the feed table. In this known construction, the shaft rod and the mandrel rod are guided in hinged guides only up to a point at a short distance in advance of the feed table, the guides also being interchangeable. The guides are changed in the case of extreme wear phenomenon and when the external diameter of the mandrel rod, and thus also of the shaft rod, has to be changed owing to the fact that, for example, a pierced blank with a bore of different diameter has to be processed.

However, this known construction has the substantial disadvantage that it is not suitable for deforming pierced blanks of great length, such as those having a length of three to four metres and in excess thereof. However, pierced blanks of this length enable seamless tubes to be produced in a substantially more economic manner and, for this reason, endeavours have been made in recent times to use pierced blanks of the greatest possible length. Owing to the absence of guides in the region of the feed table in the known push benches, pierced blanks of great length involve the risk that the pierced blanks will veer off laterally or upwardly and/or the mandrel rod and the shaft rod will buckle in the region of the feed table.Pierced blanks of great length require a correspondingly long feed table and, in the known construction, this leads to long unguided lengths of the mandrel rod and the shaft rod in this region.

An object of the invention is to provide a push bench of the type mentioned initially which is particularly suitable for the processing of pierced blanks of great length.

Accordingly the invention provides a push bench in which guides are disposed in the region of a feed table adapted to support a pierced blank to be deformed and surround the greater portion of the peripheries of the pierced blank, and of a shaft rod and mandrel rod thereon for the purpose of centering and supporting the same as the shaft rod pushes the pierced blank with the mandrel rod therein through the push bench, the guides defining guide openings which can be changed before and during the pushing operation in dependence upon the working cycle of the push bench, whereby the guide openings conform to the differing diameters of the pierced blank and the shaft and mandrel rods.

This means that, in the first instance, satisfactory guidance for the pierced blank and also for the shaft rod and the mandrel rod is also provided in the region of the feed table. Veeringoff or buckling of the pierced blanks and of the rods can also be reliably prevented in an advantageous manner in the region of the feed table. In the first instance, the guides surround the pierced blank at several locations around the larger portion of its circumference as the commencement of the working cycle of the push bench, whilst the same guides subsequently have to guide the smaller diameter rods when the pierced blank has been pushed forwardly from the feed table from the region of the guides provided at this location.This is rendered possible by virtue of the fact that the configuration and the size of the guide openings are variable before and during the pushing operation in dependence upon the working cycle of the push bench. It is important that the guide openings are varied very rapidly, namely immediately after the pierced blank has left the region of the relevant guide, to ensure that the non-guided length of the mandrel rod and of the shaft rod remains as short as possible.

In a preferred embodiment of the invention, the guides comprise guide discs which are arranged above and below the centre of the pierced blank and of the rod and are rotatable about axles extending transversely of the pushing direction, which guide discs are lockable in various rotary positions and have differing circumferential portions for forming different guide openings. In this manner, it is possible rapidly to vary the guide openings before and during the working cycle without large masses having to be moved for this purpose or having to interchange anything. It is thereby advisable for the guide discs to be overhung-mounted on their axles. The guide discs can be rapidly and simply interchanged in the event of a change of dimension.

Furthermore, it is advantageous to arrange the differing circumferential portions of the guide discs in a sequence corresponding to the working cycle of the push bench, and to construct the guide discs so as to be rotatable in only one direction of rotation. There is then no need for the drive of the guide discs to be reversible. With a constant direction of pushing, the guides are loaded in only one direction of rotation which can then be locked by, for example, a stop pawl. The drive for the guides is then always freely rotatable for the purpose of adjusting the guides in the direction of rotation opposite to that in which the stop pawls are effective.

According to a further preferred feature of the invention, the guide discs disposed below the centre of the pierced blank and of the rods need have only circumferential portions for guiding the shaft rod and the mandrel rod, and the other circumferential portions need touch neither the rods nor the pierced blanks. Since the bottom circumferential portions of the pierced blanks in any case rest on the feed table, the lower guide discs need guide only the shaft rod and the mandrel rod, whilst they otherwise can remain out of engagement.

The invention if further described, by way of example, with reference to the drawings, in which: Fig. 1 is a longitudinal section through the feed table of a push bench; Fig. 2 is a plan view of the feed table of a push bench; Fig. 3 is a section taken on the line Ill-Ill of Fig. 2.

Referring to Fig. 1, roller stands 2 (indicated only by broken lines) of a push bench are arranged in tandem on a roller stand bed 1. A feed table 3 is located in advance of the roller stand bed 1 and has support surfaces 4 which are bevelled, and which are thus of channel- or groove-like construction, in the region of the centre 5 of the pierced blanks and rods. A pierced blank 6 is placed onto the feed table 3 from one side, namely into the channel-like depressions 7 formed by the support surfaces 4. A mandrel rod 8 is inserted into the pierced blank 6 from its trailing end and engages the closed leaching end of the blank 6 to push the latter through the sizing passes of the roller stands 2 in the push direction X, the mandrel being pushed by a shaft rod (not shown).

Two guides 9 are provided in the region of the feed table 3 between the support surfaces 4, each guide comprising an upper guide disc 10 and a lower guide disc 11.

The upper guide disc 10 has a total of three circumferential portions 12, 1 3 and 14 of differing configuration and which thus form differing guide openings. The circumferential portion 12 opens the guides 9 towards the side from which the pierced blanks 6 are introduced.

The guides 9 are illustrated in this position in the drawing. The guide discs 10 are rotated in the direction of the arrow Y, the only direction of rotation permitted by a stop pawl (not illustrated), until the circumferential portion 13 is located below the axle 1 5. This circumferential portion 13 forms, together with the support surfaces 4, a satisfactory guide for pierced blank 6. As soon as the trailing end of the pierced blank 6 has moved from the region of the respective guide 9, the guide is further rotated about its axle 1 5 in the direction Y until the circumferential portion 14 reaches its bottom most position. The guide opening has then become smaller and is then able to guide the smaller diameter mandrel rod 8 and the shaft rod (not shown) which is again a few centimetres smaller in diameter than the pierced blank.

The lower guide discs 11 rotate in a corresponding direction through the same angle as the upper guide discs 10, although only one circumferential portion 1 6 of each guide disc 11 is constructed and dimensioned such that the guide discs are able to guide the shaft rod and the mandrel rod 8. The circumferential portion 1 6 is in its highest position when the circumferential portion 14 of the upper guide disc 10 0 has just assumed its lowest position. The other circumferential portions of the lower guide discs 11 are constructed and dimensioned such that they cannot touch the pierced blank 6 or either of the rods.

Fig. 3 shows that the upper guide disc 10 and the lower guide disc 11 are over-hung mounted and are rotated in synchronism with one another by way of gear wheels 1 7 and 1 8 having equal numbers of teeth. The rotary movement is produced by a stepping motor (not illustrated) or some other unit which acts upon a drive journal 1 9. The rotary movement is then effected in dependence upon the drive of the push bench and thus upon the position of the pierced blank 6 and of the mandrel rod 8.

Fig. 3 clearly shows that the pierced blank 6 can be inserted from the support surface 4. It is indicated that the size of the pierced blank 6 can be varied to a great extent by lateral displacement of the support surface 4. It will also be seen that the lower guide disc 10, when in this position, does not touch the pierced blank 6.

Claims

1. A push bench for the manufacture of seamless tubes, in which guides are disposed in the region of a feed table adapted to support a pierced blank to be deformed and surround the greater portion of the peripheries of the pierced blank, and of a shaft rod and mandrel rod thereon for the purpose of centering and supporting the same as the shaft rod pushes the pierced blank with the mandrel rod therein through the push bench, the guides defining guide openings which can be changed before and during the pushing operation in dependence upon the working cycle of the push bench, whereby the guide openings conform to the differing diameters of the pierced blank and the shaft and mandrel rods.

2. A push bench as claimed in claim 1, in which the guides comprise guide discs which are arranged above and below the centre of the pierced blank and of the rods and are rotatable about axles extending transversely of the pushing direction, which guide discs are lockable in various rotary positions and have differing circumferential portions for forming different guide openings.

3. A push bench as claimed in claim 2, in which the guide discs are overhung-mounted on their axles.

4. A push bench as claimed in claim 2 or 3, in which the differing circumferential portions of the guide discs are arranged in a sequence corresponding to the working cycle of the push bench, and the guide discs are rotatable in only one direction of rotation.

5. A push bench as claimed in claim 2, 3 or 4 in which the lower guide discs only have circumferential portions for guiding the shaft rod or the mandrel rod, and the other circumferential portions do not touch the rods or the pierced blanks, the pierced blanks being guided at their undersides by the feed table.

6. A push bench constructed and adapted to be used substantially as herein described with reference to and as illustrated in the drawings.