DK179233B1 - Roller mill and method for comminuting brittle grinding stock - Google Patents

Abstract

A roller mill according to the invention for comminuting brittle grinding stock, comprises at least one grinding roller and a counter-surface, wherein the grinding roller comprises a shaft and a roller body that are connected to each other by means of a shrink fit. Furthermore, a heating unit for heating up the shaft in the region of the shrink fit is provided.

Description

<¹θ> DANMARK (10)

<¹²> PATENTSKRIFT

Patent- og

Varemærkestyrelsen (51) Int.CI.: B02C 4/44(2006.01) (21) Ansøgningsnummer: PA2011 70621 (22) Indleveringsdato: 2011-11-15 (24) Løbedag: 2011-11-15 (41) Aim. tilgængelig: 2012-05-16 (45) Patentets meddelelse bkg. den: 2018-02-19 (30) Prioritet: 2010-11-15 DE 10 2010 060 557.3 (73) Patenthaver: ThyssenKrupp Polysius AG, Graf-Galen-Str. 17, DE 59269 Beckum, Tyskland (72) Opfinder: Thomas Rüther, Eickendorfer Weg 51 A, D-48317 Drensteinfurt, Tyskland Alexander Peters, Gartenstrasse 157, D-59269 Beckum, Tyskland Daniel Frerich, Alter Schulweg 8, D-59556 Lippstadt, Tyskland Nils Hörster, Wagenfelstrasse 6, D-59320 Ennigerloh, Tyskland (74) Fuldmægtig: Chas. Hude A/S, H.C. Andersens Boulevard 33,1780 København V, Danmark (54) Benævnelse: Roller mill and method for comminuting brittle grinding stock (56) Fremdragne publikationer:

GB 514327 A DE 10024851 A1 EP 1661624 A1 (57) Sammendrag:

A roller mill according to the invention for comminuting brittle grinding stock, comprises at least one grinding roller and a counter-surface, wherein the grinding roller comprises a shaft and a roller body that are connected to each other by means of a shrink fit. Furthermore, a heating unit for heating up the shaft in the region of the shrink fit is provided.

Fortsættes ...

LQ

Roller mill and method for comminuting brittle grinding stock

The invention relates to a roller mill and to a method for comminuting brittle grinding stock.

The roller mill of interest here comprises at least one grinding roller and one counter-surface, wherein the counter-surface can be formed, for example, by a grinding table (vertical mil) or a second grinding roller (roller press, material bed roller mill). The at least one grinding roller comprises a shaft and a roller body that are connected to each other by a shrink fit.

In practice, every now and then the roller body slips off its grinding roller and suffers damage and the surfaces of the shrink fit on the grinding shaft and grinding roller may also be damaged at the same time. Whereas the shrink fit seat on the grinding shaft can usually be repaired, the roller body is generally discarded, with the result that apart from financial loss, relatively long downtimes of the roller mill also have to be tolerated.

The invention therefore addressed the problem of specifying a roller mill and a method for comminuting brittle grinding stock in order to minimise weakening of the shrink fit between shaft and roller body.

That problem is solved according to the invention by the features of claims 1 and 9.

The roller mill according to the invention for comminuting brittle grinding stock comprises at least one grinding roller and one counter-surface, wherein the grinding roller comprises a shaft, especially a solid shaft, and a roller body that are connected to each other by a shrink fit. In addition, a heating unit for heating up the shaft in the region of the shrink fit is provided. Especially, the heating and cooling unit may be embedded in the shaft.

In the method according to the invention for comminuting brittle grinding stock using such a roller mill, the shaft is heated up if the shaft temperature is lower than the roller body temperature and the temperature difference between shaft and roller body exceeds a predetermined first desired value.

During the trials on which the invention is based, it became apparent that a weakening of the shrink fit can occur above all during the starting phase of the grinding operation, especially if the temperature of the feed material amounts to more than 120°C. This has the effect that first of all the roller body heats up correspondingly and because of the heat capacity of the roller body temperature equalisation between the shaft and the roller body is only very slow. Just in the warm-up phase therefore, the temperature differences between roller body and shaft are more than 30°C. At such temperature differences, the possibility cannot be ruled out that the shrink fit between roller body and shaft will become loose and the roller body will accidentally slip off.

It is already known from practice to cool the shaft ends in order in particular to protect the bearings. Usually, this cooling is started right from the beginning, so that the above-described effect is yet further intensified.

Owing to the heating unit provided according to the invention in the region of the shrink fit in order to heat up the shaft, it is possible to even out in particular the initial temperature difference between roller body and shaft, with the result that the shrink fit can be reliably prevented from becoming loose.

Although facilities for temperature control, in particular also for heating up grinding rollers, are known from DE 100 24 851 A1 and EP 1 661 624, these heating units serve a different purpose. In addition, the problem addressed by the invention does not arise there, because no shrink fit is provided between the shaft and roller body. Accordingly, no heating unit is provided in the region of the shrink fit.

Further embodiments of the invention form the subject matter of the subsidiary claims.

According to a further preferred embodiment of the invention, the heating unit is formed by electrical heating elements arranged in the shaft.

Furthermore, provision can be made for the shaft to be operatively connected to a cooling unit for cooling the shaft. The heating and/or cooling unit can alternatively be formed by at least one fluid circulation system.

According to a further special embodiment of the invention, the shaft comprises two ends rotatably mounted in bearings and the connection to the roller bodies is provided in a middle region of the shaft, the shaft ends being operatively connected to a fluid circulation system and the middle region of the shaft being operatively connected to a second fluid circulation system for controlling the temperature of the shaft.

Instead of or in addition to the second fluid circulation system, the electrical heating elements arranged in the shaft can also be provided.

The fluid circulation systems can here be in the form of either a water, brine or thermal oil circulation system.

In order to regulate the heating and/or cooling units, in particular a first temperature sensor can be provided for measuring the temperature of the shaft and a second temperature sensor can be provided for measuring the temperature of the roller body. Alternatively or additionally, however, at least one sensor for measuring the compressive stress in the region of the shrink fit between shaft and roller body can be used.

As soon as the shaft temperature is higher than the roller body temperature and the temperature difference between shaft and roller body exceeds a predetermined second desired value, according to a further embodiment of the method, the shaft is cooled in the region of the shrink fit.

Further advantages and embodiments of the invention are explained in detail hereafter by means of the description and the drawings, in which:

Fig. 1 shows a schematic illustration of a grinding roller of a roller mill according to the invention.

The schematically illustrated grinding roller 1 of a roller mill comprises a roller body 2 and a shaft 3 that are connected to each other by means of a shrink fit 4 (illustrated by a broken line). The shaft 3 has two shaft ends 3a, 3b that are rotatably mounted in bearings 5, 6. The shrink fit 4 is provided in a middle region 3c of the shaft 3.

The shaft ends 3a, 3b are connected to a cooling unit 7 in the form of a first fluid circulation system. For that purpose, cooling coils 7a, 7b that are connected to a pump 7c and a cooler 7d are embedded in the shaft ends 3a,

3b.

Similarly, the middle region 3c of the shaft is operatively connected to a heating and cooling unit 9 in the form of a second fluid circulation system, in order either to heat up or cool the middle region 3c of the shaft. For that purpose, suitable heating and cooling coils 9a that are connected to a pump 9b, a cooler 9c and a heater 9d are in turn embedded in the middle region of the shaft 3c.

As required, either the cooler 9c or the heater 9d is activated via a control means 8.

Furthermore, a first temperature sensor 10 that is connected to the middle region 3c of the shaft is provided for measuring the shaft temperature in said region. Correspondingly, a second temperature sensor 11 is connected to the roller body 2 in order to measure the roller body temperature. A third and fourth temperature sensor 12 and 13 respectively are additionally provided to measure the temperature in the region of the shaft ends 3a and 3b respectively.

Instead of or in addition to the two temperature sensors 10, 11, in the region of the shrink fit 4 between shaft 3 and roller body 2 a sensor 14 can be provided for measuring the compressive stress in the region of the shaft and the roller body as an indicator of the joint stress. All sensors and the cooling unit 7 and the heating and cooling unit 9 are connected to the control means 8 (see broken lines in the drawing).

By means of the two temperature sensors 10, 11, a temperature difference between shaft 3 and roller body 2 can be detected and compared with a first desired value. If the shaft temperature measured by the first temperature sensor is lower than the roller body temperature measured by the second temperature sensor 11 and if, furthermore, the temperature difference between shaft and roller body exceeds a predetermined first desired value of, for example, 20°C, the heater 9d and the pump 9b are activated via the control means 8 in order to heat up the middle region 3c of the shaft and hence correspondingly reduce the temperature difference with respect to the roller body. This situation will normally arise in the initial phase of the grinding operation, when the shaft and the roller body are still cool and hot grinding stock is being fed in.

Instead of the temperature measurement or in addition thereto, the quality of the shrink fit can be monitored by a compressive stress measurement by means of the sensor 14; if the value is too low in the initial phase, the shaft is likewise heated up.

Should a shaft temperature that is higher than the roller body temperature be determined from the measurement results of the two temperature sensors 10,

11, and should in addition the temperature difference between shaft and body exceed a predetermined second desired value, cooling of the shaft in the middle region 3c is achieved by activating the cooler 9c and the pump 9b. The coolant used can be, for example, water, brine or thermal oil.

Because of the rotary motion of the grinding roller, in normal operation the temperature in the region of the shaft ends 3a, 3b increases markedly, so that the cooler 7d and the pump 7c are correspondingly activated by the control means 8 according to the temperature measured by the third and fourth temperature sensors 12 and 13 respectively.

Heating of the middle region 3c of the shaft 3 is effected in the above-described exemplary embodiment by means of the heating and cooling unit 9. It would also be possible, however, for the heating up to be effected exclusively or additionally by electrical heating elements 15 arranged in the shaft 3 and which are likewise controlled by the control means 8.

Using the above-described heating unit, which can be formed by the heating and cooling unit 9 and/or by the heating elements 10, it is possible to heat up the shaft in the region of the shrink fit, whereby the operating reliability of the grinding roller is increased.

Claims (3)

claims A mill for crushing brittle grinding material, said mill having at least one grinding roller (1) and a counter surface, wherein said grinding roller (1) comprises a shaft (3) and a roller body (2) connected to each other by by means of a shrink fit, characterized by a heating unit (9) for heating the shaft (3) within the region of the shrink fit (4). 2. I I Claims Nos: because they relate to parts of the patent application that do not comply with the prescribed requirements to such an extent that no meaningful search can be performed, specifically: Rolling mill according to claim 1, characterized in that the heating unit (9) is formed by electric heating elements (15) arranged in the shaft. Rolling mill according to claim 1, characterized in that the shaft (3) is further functionally connected to a cooling unit (7) for cooling the shaft. Rolling mill according to claim 3, characterized in that the heating and / or cooling unit (7, 9) is formed by at least one fluid circulation system. Rolling mill according to claim 1, characterized in that the shaft (3) comprises two shaft ends (3a, 3b) rotatably mounted in bearings (5, 6) and the connection of the roller body (3) is provided in a central region (3c). of the shaft (3), whereby the shaft ends (3a, 3b) are operably connected to a first fluid circulation system for controlling the temperature of the shaft, and the central region (3c) of the shaft (3) is operably connected to a second fluid circulation system. Rolling mill according to claim 5, characterized in that at least one of the two fluid circulation systems is formed by means of a water, saline or thermal oil circulation. Rolling mill according to claim 1, characterized in that a first temperature sensor (10) is provided for measuring the temperature of the shaft (3) and a second temperature sensor (11) for measuring the temperature of the roller body (2). Rolling mill according to claim 1, characterized in that at least one sensor (14) is provided for measuring the compressive stress in the region of the shrinkage fit between the shaft and the rolling body. 5 A method for comminuting brittle milling material with a rolling mill according to one or more of the preceding claims, wherein the shaft (3) is heated if the shaft temperature is lower than the temperature of the roller body and the temperature difference between the shaft (3) and the roller body (2) exceeds a predetermined first desired value. The method of claim 9, wherein the shaft (3) is cooled in the region of the shrink fit when the shaft temperature is higher than the roller body temperature and the temperature difference between the shaft (3) and the roller body (2) exceeds a predetermined other desired value. LQ IMmsH Fäto? Asm Öma SEARCH REPORT - PATENT Application No. PA 2011 70621 1. 1 1 Certain claims were found unsearchable (See Box No. I). 2. 1 1 Unity of invention is lacking prior to search (See Box No. II). A. CLASSIFICATION OF SUBJECT MATTER B 02 C 4/44 (2006.01) According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED PCT minimum documentation searched (classification system followed by classification symbols) CPC, IPC: B02C Documentation searched other than PCT minimum documentation DK, NO, SE, FI: IPC classes as above. Electronic database consulted during the search (name of database and, where practicable, search terms used) EPODOC, WPI C. DOCUMENTS CONSIDERED TO BE RELEVANT Category * Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim no. A GB 514327 A (SMALL) 06.11.1939, see claim 1. 1-10 A DE 10024851 Al (ERICH NETZSCH GMBH & CO HOLDING KG) 1-10 31.01.2002, see abstract. A EP 1661624 Al (F.B. LEHMANN MASCHINENFABRIK GMBH) 31.05.2006, 1-10 see abstract. 1 1 Further documents are listed in the continuation of Box C. * Special categories of cited documents: P Document published prior to the filing date but later than the A Document defining the general state of the art which is not a priority date claimed. considered to be of particular relevance. T Document not in conflict with the application but cited to D Document cited in the application. understand the principle or theory underlying the invention. Έ Earlier application or patent but published on or after the filing date. ^X Document of particular relevance; the claimed invention cannot be considered novel or cannot be considered to involve an inventive L Document which may throw doubt on priority claim (s) or which is _{when ώ document is taken alone} . cited to establish the publication date of another citation or other special reason fas specified ⁵ »Y Document of particular relevance; the claimed invention cannot be considered to involve an inventive step when the document is "°" Document referring to an oral disclosure, use, exhibition or other combined with one or more other such documents, such ^means ' combination being obvious to a person skilled in the art. Document member of the same patent family. Danish Patent and Trademark Office Date of completion of the search report Helgeshøj Allé 81 5 September 2017 DK-2630 Taastrup Denmark Authorized officer Anders Budtz-Olsen Telephone No. + 45 4350 8000 _Λ Facsimile No. +45 4350 8001 ^{1 ele} P ^{hone No} · + ^{45 4350 8334} Search Report SEARCH REPORT - PATENT Application No. PA 2011 70621 C (Continuation). DOCUMENTS CONSIDERED TO BE RELEVANT Category * Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim no. Search Report SEARCH REPORT - PATENT Application No. PA 2011 70621 Box No. In Observations where certain claims were found unsearchable This search report has not been established in respect of certain claims for the following reasons:! □ Claims Nos: because they relate to subject matter not required to be searched, namely: 3. I I Claims Nos .: because of other matters. Box No. II Observations where unity of invention is lacking prior to the search The Danish Patent and Trademark Office found multiple inventions in this patent application, as follows: Search Report SEARCH REPORT - PATENT Application No. PA 2011 70621 SUPPLEMENTAL BOX Continuation of Box [.] Search Report