WO1994007643A1

WO1994007643A1 - Means for reconditioning of thread tops in a screw press

Info

Publication number: WO1994007643A1
Application number: PCT/NO1993/000145
Authority: WO
Inventors: Bjørn HANSEN; Torbjørn HAUGER
Original assignee: Kvaerner Eureka A/S
Priority date: 1992-10-01
Filing date: 1993-09-30
Publication date: 1994-04-14
Also published as: NO175928C; NO923832L; AU5158593A; CA2145872A1; SE504983C2; SE9501078L; SE9501078D0; NO923832D0; NO175928B

Abstract

A means is described for milling of the thread tops in a screw press. The means is characterized in that it comprises guide rails (10) for mounting in a housing section (1) of a screw press, along opposing sides of the press. It includes a slide (12) in each guide rail (10), an arcuate carrier (11) conforming to the curvature of the thread top, which spans the screw press between the guide rails (10). The means further includes a trolley (13) in the carrier (11) for movement along the curve, a holding device (13, 24, 25, 32, 27) for a grinding apparatus (14) in the trolley and guide means (44) on the trolley, for guiding it and the carrier along a thread flank.

Description

MEANS FOR RECONDITIONING OF THREAD TOPS IN A SCREW PRESS

The invention relates to a means for milling of thread tops in a screw press. In a screw press, the threads or wings of the press screw are exposed to wear on the top, particularly on that part of the screw located in the high pressure strainer section. As a part of maintenance, therefore, a surface coating of worn thread wings is undertaken from time to time, by welding on a layer of hard metal. After the surface coating is welded on, it is necessary to mill or grind the surface coating to nominal diameter.

The aim of the invention is to provide a means for enabling such milling in situ, i.e., without the need to remove the screw from the screw press and to mount it on a suitable milling bench.

Therefore, according to the invention, a means is proposed for milling of the ^'thread tops in a screw press, as disclosed in the independent patent claim. Additional features of the device are recited in the dependent claims.

By means of the invention it is possible to perform the necessary milling while the screw is situated in the screw press housing, in that one needs merely to remove the surrounding upper housing section and the upper part of the strainer jacket. The device is clamped securely in place by using the strainer jacket rest, or support, and the longitu¬ dinal joint flanges of the remaining part of the strainer jacket. After milling of the peripheral area over which the device is fastened, the screw is rotated to permit milling of the underlying peripheral portion of the screw.

From NO-B2 156555 there is known a means for the repair or calibration of a screw. Therein is described a trolley-like object that moves along guide rails on either side of the screw. This trolley supports a machining tool. The rails are situated in a carriage, however, which means that the screw must be removed from the screw press. During milling or similar work, the screw is rotated while the tool stands still, after having first been properly positioned relative to the screw.

The invention will be explained in more detail with reference to the drawings, where:

Fig. 1 is a sectional view of a screw press, where an upper housing part and a portion of the strainer jacket are removed to expose the relevant section of the screw press.

Fig. 2 is a device according to the invention mounted on the exposed section of the press screw of Fig. 1,

Fig. 3 is a relatively schematic cross-section of the press screw and the mounted device according to the invention,

Fig. 4 is a section along line IV-IV in Fig. 5, and

Fig. 5 is a top view of the carrier, which is included as a part of the device according to the invention.

Fig. 1 (and Fig. 2) is a sectional view of a conventional screw press, more specifically a section of the strainer area

1 of the screw press. This strainer area 1 consists of two joined, semicircular strainer shells situated between the housing sections 2 and 3 of the screw press. In Figs. 1 and

2 only the lower strainer shell 4 is shown, the complementary upper strainer shell having been removed so as to allow a view in Figs. 1 and 2 of the actual press screw 5 with its screw wing or thread 6; in other words, the screw press is in a state allowing access to half of the circumferential area of the press screw in strainer section 1. On the end face of housing section 2 we see a strainer jacket rest 7, forming a seat for the two halves of the strainer jacket in their mounted state. The two strainer jacket halves are flanged together in their longitudinal direction by means of longitudinal strainer jacket flanges 8.

It is the thread top 9 that is worn and which must be rebuilt by welding to compensate for the wear, and it is this type of surface coating that is to be milled with a means according to the invention.

In Fig. 2 a means according to the invention is shown mounted in position in the screw press. Along the length of flange 8 is mounted a guide rail 10. A corresponding guide rail is found on the other side of the press screw, i.e. , diametrically opposed to the one shown.

A carrier 11 extends over the exposed press screw section, between two trolleys 12, it being understood that the guide rail that is not visible also supports a trolley correspond¬ ing to the trolley 12 shown in Fig. 2 (see Fig. 3).

In carrier 11 is provided a tool holder 13 supporting a milling apparatus 14. Holder 13 is movable along the trolley 11, which curves with an arcuate shape corresponding to the curvature of thread top 9 (see Fig. 3).

Carrier 11 is movable with the aid of trolleys 12 along guide rails 10, and holder 13 is movable along carrier 11, as indicated by the double arrow in Fig. 3, thus enabling the milling apparatus to cover the entire exposed area of the press screw.

Guide rail 10 has the configuration of a C-profile, there being formed at the top and bottom thereof trackways cooperative with small running wheels 15 mounted on trolley

12. Guide rail 10 is fitted against jacket flange 8 with the aid of angle adaptor pieces 16, which are supported by flange 8 and with one leg thereof in abutment with strainer jacket guide rest 7. By this means the precise fixation of the rail mounting is secured, permitting a symmetrical and, relative to the press screw 5, concentric arrangement of the arcuate carrier 11.

Carrier 13 consists primarily of a frame composed of two curved longitudinal members 17,18 (Fig. 5) and three transverse members 19,20,21. A milling apparatus (14) is mounted in the carrier, in a manner to be described in more detail below.

The support member 20 is formed as shown in Figs. 4 and 5 with two brackets 22,23, and suspended in these brackets with the aid of respective stays 24 is a pivot bearing 25 to provide support for milling apparatus 14, enabling the rotation thereof as indicated by double arrow 26. The pivotable movement is controlled by a steering wheel mechanism 27, consisting of a steering wheel 28 having connected thereto an internally threaded hub into which is screwed from e^ach end a screw bolt associated with a respective ball joint 30,31. Ball joint 30 is connected to a clamp bar 32, which is clasped around milling apparatus 14, and ball joint 31 is pivotably mounted in a bracket 33 on the transverse member 21.

In Fig. 5 the upper half of the holder is shown without its associated members, while the lower half is shown with the associated support and wheel members.

On transverse member 19 are mounted two lateral guide wheels 34,35, adapted for guiding engagement with the vertical sides of two arcuate members 36,37 (see Fig. 2). Mounted in the two longitudinal members 17,18 of holder 13 are guide wheels 38,39, adapted for guiding contact against the top edge of the respective part 36,37. In addition, there is mounted in each longitudinal member 17,18 a guide wheel 40, which rests against the under surface of arcuate members 36,37.

Pivotably mounted on transverse member 19 by means of two pivot pins 41,42 is a transverse member 43 in the carrier, supporting two guide wheels 44; see Fig. 4, where only one of said guide wheels is shown. These guide wheels 44 are each mounted in their respective elongate apertures 45,46 (Fig. 5), enabling adjustment of the distance between them in accordance with the breadth of screw wing 6, against the flanks of which guide wheels 44 operate, in order thereby to guide holder 13 along the course of the screw wing.

Transverse member 43 is upwardly swingable as indicated by the arrow, in order thereby to bring guide wheels 44 into an upwardly rotated position where they run clear of the screw wing or thread 6.

When the device is to be used for milling of the screw wing top 9, said device is mounted as shown in Fig. 2, the rails 10 being screwed securely by means of angle adaptor pieces 16 to the respective strainer jacket flanges 8, with the angle adaptor pices 16 in abutment with guide rest 7 for the strainer jackets. Arcuate members 36,37 will thereby be positioned concentrically relative to press screw 5. Milling apparatus 14 is adjusted by means of steering wheel mechanism 27, thus ensuring the milling apparatus grinding wheel 47 of the desired grinding contact with screw wing top 9. The milling apparatus is started, and holder 13 may then be moved for the milling operation, as indicated by the double arrow in Fig. 3. The illustrated milling apparatus has a practical mill g are? f about 60°. After completion of the milling of oi.e sectOi , screw 5 is rotated accordingly, whereafter a new sector may be milled. Milling to a desired radius or diameter for screw wing top 9 is controllable by means of insertion of a simple gauge between the under surface of a member 36,37 and screw wing top 9. The use of such a simple standard spacing member (not shown) naturally facilitates the milling.

During movement of holder 13 as indicated by the double arrow in Fig. 3, it will be guided by wheels 38,39,40 and 34,35 on trolley 11, while guide wheels 44 run on the screw wing flanks, steering the holder and thereby also trolley 11 in accordance with the helical course of the screw wing.

In the embodiment shown and described, a standard angle grinder is used as milling apparatus 14.

Claims

P a t e n t C l a i m s

1.

A means for milling of the thread tops on the screw in a screw press, which screw press includes a strainer section having an upper and a lower semicircular strainer shell, each strainer shell having longitudinal joint edges with which it is connected to the other strainer shell, and where in the adjacent parts of the screw press are guide rests for the strainer shells, said means comprising guide rails (10) for placement along each side of the screw, a trolley (12) mounted for movement along the guide rails over and along the screw, a milling tool holder (13) on the trolley for a milling tool (14) for grinding of the thread tops, and guide means (44) connected to the milling tool to guide it along a thread flank on the screw, c h a r a c t e r i z ed i n that the guide rails (10) are each adapted for mounting along its respective joint edge (8) on the lower strainer shell (4), and that a guide carrier (11) is provided in the trolley to support the milling tool holder (13), which guide carrier extends between the guide rails (10) in a curvature such that, when the apparatus is in mounted state, said guide carrier (11) will be concentric in relation to the screw (6).

2.

A means according to claim 1 , c h a r a c t e r i z e d by mounting/adaptor pieces (16) connected to the guide rails for fixed attachment to the guide rest (7) for the upper strainer jacket in the screw press.

3.

A means according to one of the preceding claims, c h a r a c t e r i z e d i n that the holder for the milling tool has means (27) for regulating the position of the milling tool (14) relative to the thread top (9).

4.

A means according to one of the preceding claims, c h a r a c t e r i z e d i n that said guide means (44) are pivotably mounted (41,43) for rotation into and out of steering engagement with the thread flank.