NZ541201A - Method for producing fittings for mechanically processing paper stock containing water - Google Patents

Abstract

Disclosed is the production of fittings, used e.g. in refiners for pulverising paper stock. The disclosed accessory consists of a base body (1), a mask (3) lying on said body, in addition to processing elements (5) which process the stock. The processing elements (5), e.g. strip-type blades, are inserted into the mask (3), which is provided with corresponding cavities (4). A fixed bond is subsequently produced by a high-temperature soldering process. The stated advantage of this method is that optimal materials can be selected for the processing elements and that the production method is flexible and particularly cost-effective in terms of the quality of the produced fittings.

Description

uh* ;METHOD FOR PRODUCING FITTINGS FOR MECHANICALLY PROCESSING PAPER STOCK CONTAINING WATER ;The invention relates to a process for producing fittings according to the preamble of Claim 1. ;Fittings made in this way can be applied especially in milling paper fibre, dispersing contaminants in the paper stock or deflaking, thus dissolving paper stock agglomerates. They are also used in grinding machines (refiners), deflakers or dispersers. Such machines have at least one rotor and at least one stator with either discoid or conical surfaces, to which the fittings are attached, so that gaps can form between them. Many fittings have links and grooves on the working surfaces, giving rise to so-called blade fittings. Other fittings, e.g. as inserts in dispersers, have the form of toothed rings. DE 195 23 704 A1 discloses and describes disperser fittings. It is known that, apart from the form of the links, grooves and teeth, the material they comprise also has an effect on the processing of the fibre. ;With mechanical processing using such fittings the paper stock is present in a pumpable suspension, with a solids content of approximately 2-8 %, or as tough material with a solids content in excess of this. Dispersers generally work at a solids content of between 15 and 25 %. ;The fittings are subjected to wear and must therefore be replaced at certain intervals. But the wear can also lead to the processing effect changing. Form, in particular edge form, arid surface of the fittings have an overwhelming influence on the processing effect. The disadvantage of these changes is that from a certain point of time onwards it is no longer possible for the same machine to operate optimally. ;It is therefore understandable that for the development of fittings considerable expense is outlaid, which is lowered in the configuration of its form and in the choice of material. It has been proven that materials, which are particularly well suited for processing elements, have properties proving highly problematic when used for the base body of the fitting. In particular, this relates to materials which are very hard and brittle and therefore do not exhibit the toughness required for the base body. Further, such intellectual property office of n.z. ;2zjtov 2006 ;RECEIVED ;2 ;materials are relatively expensive in manufacture and can be processed only at considerable expense, as compared to normal metallic materials. ;The base body of a processing tool makes the connection of the processing elements to the other components, e.g. in a grinder. ;Due to the high forces occurring in such a grinding machine, high strength demands are made on the base body. It must also be possible to attach it securely to the grinding machine, for which e.g. highly braced screws are required. Because of these particular demands a particularly solid and tough material is required. ;DE 196 03 548 A1 discloses a process for making fittings, in which these are made up of separately manufactured parts. According to this publication a high-temperature soldering process can be used under vacuum for this purpose. These well-suited processes are, however, expensive to carry out and do not always result in adequate strength. ;WO 99/37402 A 1 describes a process for manufacturing refiner fittings, enabling another material to be selected for the blades than for the base plate, though it is very expensive and complicated due to the plurality of individual components which have to be fitted together precisely. ;The object of the invention is to provide a process for making fittings such that their manufacture is made substantially easier, and particularly suitable hard materials can be used for highly stressed processing elements. ;A definition of the specific embodiment of the invention claimed herein follows. ;In a broad format, the invention provides a process for manufacturing fittings (2) for mechanical processing, in particular grinding of aquiferous paper stock, which are made up of ;- at least one base body (1,1', 1") and • ;- at least one processing unit contacted by the paper stock with operational use of the fitting (2), which has a plurality of protrusions formed from processing elements (5, 5'), ;intellectual property office of n.z. ;21 nov 2006 ;RECEIVED ;2a characterised in that the processing elements (5, 5') are made separately, in that a mask (3) is made, which is provided with openings (4), whereof the form corresponds to that of the foot (6) of the processing elements (5, 5'), in that the processing elements (5, 5') are set in the openings (4) of the mask (3), in that processing elements (5, 5') and mask (3) are firmly connected to one another by fixed connections, and in that the mask (3) is connected to the base body (1,1', 1"), wherein the fixed connections are made by a high-temperature soldering process. ;The mask used for the process can comprise a sheet of uniform thickness, in which the openings have been made by laser cutting. At the same time it is quite possible to produce different openings for fittings with a different milling effect, as per requirements. Since the processing elements are first made separately, it is possible to use optimal materials for these and in the process to create the form of the fitting relatively easily. Using the mask there is the possibility of positioning the processing ;[text continues on page 3] ;intellectual property office of n.l ;21 NOV 2006 RECEIVED ;3 ;elements precisely and securely at the right places on the base body and keeping them there during the subsequent procedural step. ;Since a larger number of processing elements is generally required for a fitting, it is effective to carry out inserting the elements into the mask with the aid of an automatically operating device. The advantage of the process is not only rapid execution and good automation, but it also offers very good strength, because the processing elements can be connected both to the base body and also to the mask. A high-temperature soldering process is particularly well suited to this, with which all connections belonging to a processing unit can be made at the same time. Such processes are mostly performed at very high temperatures, e.g. over 1000°C, preferably ca. 1050°C. An inert gas atmosphere, e.g. argon, is advantageously used; also a vacuum is conceivable, though more expensive. ;The outline contour of the mask can be slightly smaller than that of the associated base body. There can also be several smaller masks assigned to a single base body, in that they are segmented in a peripheral direction. This makes the grinding technological layout of oblique blade fittings easier: since the blades of such fittings are parallel to one another on a segment, the deviation of the blade angle from the desired value can be kept smaller with a greater number of segments per base body. It is particularly economical to design the base body as a support frame, with supporting regions, in which also the bores for the fastening screws are located, required to attach in the grinding machine. Such a support frame can be constructed from superposed laminated sheets (sandwich construction), in which the fastening holes have already been made. The sandwich, the mask and the processing elements can be soldered together in a single procedural step. ;The mask can easily be connected to the base body, e.g. by welding seams in other cases prior to inserting the processing elements. ;The expensive processing of the hard structures on the processing elements can often be omitted, since the precision of the fittings made in this way is greater than e.g. in conventional fittings, thus fully cast. ;The invention will now be explained by means of diagrams, in which: ;4 ;Figure 1 shows part of a grinding fitting in the inventive manufacturing process; ;Figure 2 shows part of a grinding fitting on completion of the inventive manufacturing process; ;Figure 3 shows a special form of the processing elements; ;Figure 4 shows a 90° segment of a grinding fitting for disc refiners; ;Figure 5 a grinding fitting in section with special base body; ;Figure 6 shows part of a cone refiner provided with a grinding fitting; ;Figure 7 shows part of a disperser or deflaking fitting made according to the present invention; ;Figure 8 shows a variant of the fitting illustrated in Figure 7. ;Figure 1 shows a part of a base body 1, fitted with a mask 3, whereby the connection is made here by welded seams 7 or spot welds. The mask 3 is provided with a larger number of continuous openings 4. A processing element 5 is already inserted into the opening shown on the far left. The processing elements 5 are strip-like and can be made e.g. from rolled profiles. They have a surface constant over height, which also corresponds to that of the foot 6. The openings 4 and the form of the foot 6 match each other such that the processing element 5 can be set clearance-free into the opening 4. In typical cases, in which a high-temperature soldering process is carried out, the solder can already have been applied to the corresponding surfaces prior to inserting. Deposits of solder in the form of small depressions or grooves can be made advantageously in the components to be connected (not shown here). ;The mask 3 can also be set, thus embedded, into a correspondingly formed base body. ;Figure 2, which illustrates a finished fitting 2 both in perspective and in section, shows that the soldering surface 9 (illustrated as thickened lines) connects the processing elements 5 both to the base body 1 and also to the mask 3. Because the stress on the fitting during operation can be relatively high, this large-surface connection offers a particular advantage. The soldering surface 9 here also extends over the contact surfaces between mask 3 and base body 1, which is however not always required and increases processing expenses. The thickness c of the mask 3 is usually between 2 and 10 mm. ;5 ;The fitting 2 partially shown in Figure 2 can e.g. be understood as a grinding segment (see Figure 4) for a disc refiner, which is known to contain a plurality of strip-like processing elements 5. Such fittings are also known as blade fittings. They are provided with screw holes 10 and are screwed on to the rotor or the stator of a disc refiner. These are known to be wearing parts, which therefore must be renewed at certain intervals. ;Figure 3 shows a possibility for specially shaping the form of the processing elements 5, made easier by the inventive process. On the surface opposite the plane parallel to the direction of motion the leading edge of cut e.g. in the rotor in the direction of motion (arrow 18) has an angle a between 0 and 10 and on the front side opposite the perpendicular plane has an angle y of likewise between 0 und 10. This avoids unwanted edge rounding. ;Figure 5 illustrates in section the structure of a special embodiment of a fitting manufactured according to the present invention. It is evident that the base body 1" in the illustrated example comprises three superposed laminated sheets 19, 19', 19", which in each case can have the same thickness (e.g. 6 mm). The abovementioned laminated sheet 19 is connected, e.g. by high-temperature soldering, to an underplate 20 and this is in turn connected to the mask 3, which, as already described, was provided with processing elements 5. The base body 1" is not constructed solidly, rather it is constructed as a support frame with supporting regions, in which also the screw holes 10 are located. Cavities 21 are left free between the supporting regions in the laminated sheets 19, 19', 19", thus saving on weight and material costs. ;The underplate 20 is sized correspondingly to strength requirements (optionally also as thick as the laminated sheets 19, 19', 19") and can absorb the compression forces originating from grinding over the cavities 21. The laminated sheets 19, 19' and 19" can be soldered to one another in the same procedural step and to the underplate 20, in which the processing elements 5 in the mask 3 are also anchored. The advantage of the layered construction of the base body 1" in particular is that its production is made less expensive and that it becomes easier. The outer contour, the cavities 21 and the screw holes 10 can be produced favourably by laser cutting. ;6 ;It is also possible to apply the inventive process if a fitting for a cone refiner is to be manufactured. Then the base body 1', as shown in Figure 6, has the form of a truncated cone or a part thereof. This too can be provided with a mask 3, in which the processing elements 5 are to be inserted and fixed in the abovedescribed manner. From Figure 6 it is also evident that the fittings manufactured according to the process described can belong both to the rotor 11 and also to the stator 12. In most refiners it is known for rotor and stator to be provided with blade fittings. The suspension 14 to be ground is fed in between the blades through the machine. The rotor 11 is driven by the shaft 13. ;There are also applications in the area of dispersing and deflaking of paper stock, in which fittings are used, which are provided with highly stressed toothed processing elements. Here too the inventive process can be applied. Figures 7 and 8 accordingly each show a base body 1 with a mask 3 set on and a number of already inserted processing elements. A few different tooth forms are illustrated by way of example, e.g. single cubic teeth 15 or chamfered teeth 16, acting as processing elements in terms of the invention. It should optionally be weighed up as to whether a greater number of simply formed, easy-to-make individual teeth is used, or whether several teeth are combined into larger or smaller teeth groups 17, 17' and then inserted into the mask 3. The manufacture of such a fitting is similar, as already described, i.e. the feet of the processing elements 5', thus the teeth or teeth groups, and the openings in the mask 3 have approximately the same form, so that the processing elements 5' can be inserted. Next comes the final fixing of the processing elements with the mask 3 and the base body 1. ;Hard brittle metal alloys, which were optimised for fibre processing, can be used as material for the processing elements. They can also be hardened either after high-temperature soldering or during that process. For example, after high-temperature soldering cooling can be performed so rapidly that the processing elements harden thermally with use of carbon steels. ;The base body may comprise relatively tough Cr-Ni steel. Since it is covered up to the paper stock suspension by mask and processing elements, it can also be made of non-corrosion-resistant steel, further reducing costs. A further possibility is the coating of the base body with corrosion-resistant material. ;7 ;The mask can be made advantageously from relatively tough Cr-Ni steel sheet, in which the openings have been made by laser cutting. *

Claims (23)

8 What we claim is:

1. A process for manufacturing fittings (2) for mechanical processing, in particular grinding of aquiferous paper stock, which are made up of - at least one base body (1, 1', 1") and - at least one processing unit contacted by the paper stock with operational use of the fitting (2), which has a plurality of protrusions formed from processing elements (5, 5'), characterised in that the processing elements (5, 5') are made separately, in that a mask (3) is made, which is provided with openings (4), whereof the form corresponds to that of the foot (6) of the processing elements (5, 5'), in that the processing elements (5, 5') are set in the openings (4) of the mask (3), in that processing elements (5, 5') and mask (3) are firmly connected to one another by fixed connections, and in that the mask (3) is connected to the base body (1,1', 1"), wherein the fixed connections are made by a high-temperature soldering process.

2. The process as claimed in Claim 1, characterised in that the openings (4) pass through the mask (3).

3. The process as claimed in Claim 2, characterised in that the fixed connections of the processing elements (5, 5') are produced with the mask (3) by one procedural step, in which the processing elements (5, 5') are also connected to the base body (1,1', 1").

4. The process as claimed in any one of Claims 1-3, characterised in that the high-temperature soldering process is carried out at a temperature above 1000°C.

5. The process as claimed in Claim 4, characterised in that the high-temperature soldering process is carried out under vacuum or inert gas atmosphere.

6. The process as claimed in any one of the preceding claims, characterised in that at the same time a connection of mask (3) and base body (1, 1', 1") on its contact surfaces is made by the procedural step, in which processing elements (5, 5') and mask (3) are connected to one another. 'intellectual property officf i of n.z. 2 7-NOV 2006 BM.CE/VEDl 9

7. The process as claimed in any one of the preceding claims, characterised in that a base body (1) is made, which is configured as a support frame, with supporting regions, in which screw holes (10) for fastening screws can be located.

8. The process as claimed in Claim 7, characterised in that the base body (1") is built up from superposed, interconnected layers, in particular laminated sheets (19, 19', 19").

9. The process as claimed in Claim 8, characterised in that the layers, in particular laminated sheets (19, 19', 19"), are soldered to one another and that this is carried out at the same time with soldering processing elements (5, 5') and mask (3).

10. The process as claimed in any one of Claims 1 to 9, characterised in that the processing elements (5, 5') are hardened during cooling after high-temperature soldering.

11. The process as claimed in any one of Claims 1 to 9, characterised in that the surfaces of the processing elements (5, 5') contacted during operational use of the fitting (2) by the fibre stock are surface-treated either during or immediately after the high-temperature soldering.

12. The process as claimed in Claim 11, characterised in that the surface treatment raises the hardness and/or wear resistance of the processing elements (5, 5').

13. The process as claimed in Claim 11 or 12, characterised in that high-temperature soldering and surface treatment are carried out in the same oven.

14. The process as claimed in any one of the preceding claims, characterised in that processing elements (5, 5') and base body (1, 1', 1") are made from different materials.

15. The process as claimed in any one of the preceding claims, characterised in that base body (1, 1', 1") and mask (3) are made of materials, whereof the heat expansion coefficients are equal to a tolerance of 10 %. intellectual. property office of n.2. 2 Z NOV 2006 RECEIVED 10

16. The process as claimed in any one of the preceding claims, characterised in that the mask (3) is made from a sheet and in that the openings (4) are made by laser cutting.

17. The process as claimed in Claim 16, characterised in that the outer contour of the sheet is selected such that it corresponds substantially to the outer contour of the base body (1,1', 1").

18. The process as claimed in Claim 16, characterised in that the mask (3) is embedded in the base body (1, 1', 1").

19. The process as claimed in any one of the preceding claims, characterised in that the mask (3) is made from a Cr-Ni steel alloy.

20. The process as claimed in any one of the preceding claims, characterised in that the processing elements (5, 5') extending vertically to the base body (1,1', 1") are striplike elevations, between which grooves (8) are located.

21. The process as claimed in Claim 20, characterised in that the projection of the striplike elevations over the mask (3) is between 2 and 20 mm.

22. The process as claimed in Claim 20 or 21, characterised in that the width of the strip-like elevations is between 2 and 30 mm, preferably 2 and 10 mm.

23. The process as claimed in any one of Claims 1 to 20, characterised in that the processing elements are teeth (15, 16), which extend vertically to the base body (1, 1', 1"). Dated: 22 November 2006 intellectual property office of n.z. 2 7 NOV 2006 RECEIVED