US3158333A

US3158333A - Grinding apparatus for fibrous materials

Info

Publication number: US3158333A
Application number: US150819A
Authority: US
Inventors: Asplund Arne Johan Arthur; Penten Lars; Johansson Johan Gunnar Inge
Original assignee: Defibrator AB
Current assignee: Valmet AB
Priority date: 1960-11-08
Filing date: 1961-11-07
Publication date: 1964-11-24
Anticipated expiration: 1981-11-24
Also published as: CH406797A

Description

Y- 1964 A. J. A. ASPLUND ETAL 3,153,333

GRINDING APPARATUS FOR FIBROUS MATERIALS 7 Sheets-Sheet 1 Filed NOV. 7. 1961 INVENTORS ARNE JOHAN ARTHUR ASPLUND LARS PENTEN JOHAN GUNNAR INGE JOHANSSON BY 4 Q2 1964 A. J. A. ASPLUND ETAL 3,153,333

GRINDING'APPARATUS FOR FIBROUS MATERIALS Filed Nov. 7, 1961 7 Sheets-Sheet 2 1964 A. J. A. ASPLUND ETAL 3,158,333

GRINDING APPARATUS FOR FIBROUS MATERIALS 7 Sheets-Sheet 3 Filed Nov. 7, 1961 Nov. 24, 1964 A. J. A- ASPLUND ETAL 3,158,333

GRINDING APPARATUS FOR FIBROUS MATERIALS 7 Sheets-Sheet 4 Filed Nov. 7. 1961 Nov. 24, 1964 A. J. A. ASPLUND ETAL 3,153,333

GRINDING APPARATUS FOR FIBROUS MATERIALS '7 Sheets-Sheet 5 Filed Nov. 7, 1961 Nov. 24, 1964 A. J. A. ASPLUND ETAL 3,153,333

GRINDING APPARATUS FOR FIBROUS MATERIALS 7 Sheets-Sheet 6 Filed Nov. '7. 1961 Fig. 6

Nov. 24, 1964 A, J, A. ASPLUND ETAL 3,158,333

GRINDING APPARATUS FOR FIBROUS MATERIALS Filed Nov. 7, 1961 '7 Sheets-Sheet 7 United States Patent 3,158,333 GRINDING APPARATUS FQR FIBROUS MATERIALS Arne Johan Arthur Asplnnd, Bromma, Lars Penten,

Lidingo, and Johan Gunnar Inge Johansson, Nasbypark,

Sweden, assignors to Defibrator Alrtieholag, a corporation of Sweden Filed Nov. 7, 1961, Ser. No. 150,819 Qlaims priority, application Sweden Nov. 8, 1960 2 Claims. (Cl. 241-244) This invention relates to grinding apparatus for fibrous materials.

More particularly this invention relates to grinding apparatus for treatment of fibrous material of organic origin.

Still more particularly this invention relates to grinding apparatus for fibrous materials, said apparatus being of the type comprising a frame, a housing disposed in said frame, two grinding members enclosed in said housing one of said grinding members being secured in said housing and the other on a rotatable shaft, passing through said housing and mounted on either side of said housing on bearings carried by said frame, and compressing members, preferably in the form of a hydraulic servo-motor, for creating a grinding pressure between said grinding members.

One main object of the invention is to provide a grinding apparatus of the kind set forth provided with a device which permits the housing and the frame to be subjected to different thermal expansion while they maintain the desired parallel relation between the grinding surfaces of the grinding members.

A further object of the invention is to provide a grinding apparatus of the type set forth with a device which permits an axial movement of the housing relatively to the frame while the center position is maintained practically unchanged.

Further objects and advantages of the invention will become apparent from the following description, considered in connection with the accompanying drawings which form part of this specification and of which:

FIG. 1 is an elevation of a grinding apparatus or refiner for fibrous organic material and embodying the invention.

FIGS. 2 and 3 are vertical longitudinal sections on a larger scale of the right part and the left part, respectively, of the refiner shown in FIG. 1.

In FIG. 4 is a section taken along the line IV-1V of FIGS. 2 and 3.

FIG. 5 is a view on a larger scale made to the right of a vertical plane through the shaft axis and partly representing a section following line VV of FIG. 1; the left part of said FIG. 5 being a view partly in section along line VaVa of FIG. 1.

FIGS. 6 and 7 are sections taken along lines VI-VI and VII-VII, respectively, of FIGS. 1 and 3.

Referring to the drawings, reference numeral 10 denotes the frame of the refiner. The central portion of said frame has a recess intended to receive a separate grinding housing 12. The housing 12 encloses stationary and rotatable grinding members generally denoted by 14 and 16, respectively. The stationary grinding members 14 are rigidly mounted in the housing 12, while the grinding members 16 are secured to a shaft 18 driven via a coupling 20, by a motor 22 (FIG. 1). In known manner, the coupling 20 is of a type permitting'an axial movement of the shaft 18 in relation to the motor 22. The shaft 18 passes through and is sealed against the grinding housing 12 by means of

packing boxes

23, 24 at each end of the housing. In the grinding housing a super-atmospheric steam pressure may be maintained. The shaft 18 is carried by two bearings denoted generally by 25, 28. The two bearings are located in the frame 18 on either side of the housing 12. The bearings permit due to differences in temperature during operation.

ICC

Patented Nov. 24., 19654 an axial displacement of the shaft 18 and the grinding members 16 relatively to the housing and frame.

The grinding housing 12 is divided in a horizontal plane located above the shaft 18, its cover 30 being secured to the housing by means of a bolting 32. The opening of the housing exposed upon removal of the cover is large enough for rendering it possible to mount the grinding members through the opening. The housing 12 is secured to the frame 10 by a plurality of fastening bolts 34 the number of which in the embodiment illustrated in the drawings is three, and these bolts join the two parts on either side of the shaft. The bolts 34 are disposed so as to prevent the tensile forces transmitted through the bolts due to the grinding pressure acting between the grinding members, from creating any bending moment in the grinding housing. For this purpose the bolts 34 are fixed in the cylindrical peripheral zone of the grinding housing 12.

The grinding housing 12 has a tubular prolongation 36 in which a sleeve 37 is fitted. A gap 46 is formed between said sleeve and the shaft 18 or a wearing liner 38 protecting the shaft, for supply of stock to be ground to the grinding members at their radially inner edges. The prolongation 36 has four openings for selective connection of an inlet for the stock. Of these openings, one upper and one lower are closed by covers 42, td. In the embodiment shown the stock is received through one of two side openings 46 to which a connecting pipe 47 is attached.

The grinding housing 12 has a comparatively great axial length and is therefore carried by two supports 48 at the end opposite fastening bolts 34-. Said two supports are symmetrically disposed about a longitudinal vertical plane through the axis of shaft 18. At the top, i.e. on the level with the axis,-each support 48 is secured to the prolongation 36 of the housing 12 by means of bolts 5t} and extends therefrom downwardly to the lower part of the frame 1% Where it is secured to said frame by means of one or several bolts 52. The supports 48, which may be united at the base by a cross bar 49, thus have comparatively great vertical extension between their securing points. The supports iii prevent the grinding housing 12 from depending but at the same time they permit an axial displacement of the housing caused by the different thermal expansion of the housing and the frame which occurs when the refiner is operated. This difference is due to the fact that the housing and the'frame are constructed of materials having different coefficients of thermal expansion and, further, In this course the supports act as a kind of rocker swinging about the lower securing points. The supports may be made of sheet material and have transverse reinforcement plates 47 along a part of their length in order to prevent buckling. The supports due to the comparatively great length of their top portions describe a circular are on a practically constant level, especially as the expansion movements are small when compared with the dimensions of the frame and the housing. In this way, such movements of the grinding housing are avoided which could jeopardize the parallellity of the grinding surfaces of the grinding members 14, 16, which parallellity is of vital importance to the capacity of the grinding apparatus to deliver a uniform product of the intended grinding degree.

The fastening bolts 34 are located at the end of the housing 12 facing a hydraulic servo-motor, generally r 3 By conduits 63, 64 pressure fluid, such as oil, may be supplied to one end of the chamber and removed from its opposite end for bringing about desired movements of the piston.

The piston 58 is rigidly connected to a cover which in turn is secured to the cylindrical inner casing 66 of the bearing 26, which casing is axially displaceable on ribs as in an outer casing 70 rigidly secured to the frame 16. Two roller bearings 72, '74 of a combined axial and radial thrust type are mounted in the casing 66, which is rotationally stationary together with the piston, said bearings centering the shaft 18 and permitting, at the same time the pressure to be transmitted in both directions from the servo-motor 54 to the shaft 18 and thus to the rotating grinding members 16. The casing 66 is kept under radial pressure by means of a plurality of spring-members 76 acting on a shoe '73 which bears against the casing 66. Said shoe also serves to prevent the casing 66 from rotating. The outer bearing rings 80, 82 of the bearings 72, 74 are inserted in a retainer ring 84. This ring has axial through-bores housing spring members 86 which act on the bearing rings 80, 82, so that these are always in contact with their rollers 72 and 7'4, respectively.

The rotating grinding members 16 comprise a rotor disc 88 rigidly secured to the shaft 13 and constituting an unbroken element extending about the shaft. The

rotor 88 carries a parted segment holder 90 secured onto the rotor by means of screws 92 which may be disposed in two groups at various radial distances about the circumference. The segment holders 90 carry in turn grinding segments 94 which are provided with the grinding surfaces for treating the grinding stock. The segments 94 are greater in number than the parts of the holder 90; in the embodiment shown four segments are connected by a screw joint 96 with the respective part of the twopart holder. These screw joints are suitably disposed at three different radial distances.

The stationary grinding members 14 comprise an undivided stator ring 98 centered on the sleeve 37 forming part of the housing 12. The stator ring 98 carries a holder 1G2, suitably split in two parts, by means of bolts 104 which are arranged, as are also the bolts 92, in two groups at different radial distances. The segment holder 102 carries segments 106 secured thereto by means of screw joints 197 distributed in the same way as the screw joints 96.

The elements 94 and 1%, which are subjected to wear, are introduced together with their holders 90 and 162, respectively, into and removed from the housing 12 after the top cover 30 of said housing has been removed. The split segment holders 90, 102 are retained in their positions in the rotor 38 and the stator ring 98 by means of shoulders 91 and 1 13, respectively, provided at the periphery. The securing of the split holder 102 to the stator ring 98 is facilitated by the latter being rotatably carried on the sleeve or inlet liner 37 and turnable by means of a pin which is inserted into one of radial holes 108 formed in the periphery, according as these holes become accessible from outside. For the same purpose holes 109 are formed in the rotor disc 88. The screws 104 may be inserted into their screw holes due to an internal bracket 110 supporting the stator ring 98 while the bolts 112 are not in place and extending up into the cover 30 having a V-shaped opening 111, as is clearly seen from FIG. 4.

In known manner the grinding

segments

94, 106 are formed with channels or grooves on their interfacing surfaces, said channels or grooves extending radially or peripherally, depending on the grinding degree desired. The pressure exerted by the fibre stock when passing through the gap between the grinding'segments in the direction radially outwards, causes the rotor to deflect so that its effective grinding surface becomes slightly conical. The conicity is of course proportional to the magnitude of the grinding pressure.

Bolts 112 are threaded into the segment holders 192 1' and pass with play through the stator ring 98. The bolts 112 also pass with play through sleeve-shaped adjustment screws 114 threaded into the stationary housing 12 to abut against the stator ring 98 with their inner end portions. The adjustment screws 114 are locked by nuts 116 in the intended axial abutment position against the stator ring. The bolts 112 and adjustment screws 114 are spaced circumferentially in the stationary grinding members and thus also in the bracket 110. By arrangement of the diameter of the circle along which the adjustment screws 114 are positioned the grinding pressure load on the stationary grinding members may be distributed in such a way that the stator ring obtains by deformation the same or nearly the same form as is conditional on the conicity of the rotating grinding segments under the action of the grinding pressure. In this way the gap between the rotating and stationary grinding surfaces may be kept constant radially independent of the magnitude of the grind ing pressure. As an example, it may be stated that this effect was attained in one case when the adjustment screws 114 were disposed on a pitch circle having a diameter of 900 millimeters, the

segments

94 or 104 having an external diameter of 1100 millimeters.

In the illustrated embodiment the grinding housing 12 has three openings 113 (see especially FIG. 4) for the selective connection of an outlet for the finished fibre stock. The openings not utilized are closed by covers 117 (FIG. 2).

The servo-motor 5 5 is preferably governed by a control device which controls the pressure generated by the servo-motor in dependence of the varying supply of grinding stock, so that the width of the gap between the grinding discs is maintained almost constant and the grinding degree thus becomes uniform. A control device of this type, which thus alters the pressure in the chamber 62 on one or the other side of the piston flange 60 upon a variation of the grinding stock supply, is described in the Patent No. 2,971,704, and does not form part of the present invention. Should the control device fail for some reason or another, the grinding gap is adjusted instead by means of a device comprising a stop nut 118 threaded on the servo-motor piston 55%. This nut is provided also on its external side with a thread 120 (FIG. 7), adapted to co-operate with a worm 122 disposed on a shaft 124 and turned by a hand wheel 126. The axial position of the stop nut 118 is adjusted by means of the hand wheel 126 in such a way as to cause the grinding gap between the grinding members 14, 16 to obtain its intended minimum value when the stop nut is brought to engagement with a thrust bearing 128 in the stationary servo-motor casing 56. During grinding, the fluid pressure is only conducted to the left end of the chamber 62, as viewed in FIG. 3. The stop nut 118 ensures that disturbing metallic contact does not occur between the grinding surfaces. By manual reversing of the pressure fluid flow to the right side of the servo-motor flange 60 the grinding members are brought apart.

The bearing 28 does not absorb but the radial load from the shaft 18 and for this purpose it is provided with a spherical roller bearing 13!) mounted in an inner cylindrical bearing casing 132. The latter is axially slidable in an outer bearing casing 134 and is actuated by spring members 136 via a shoe 138 which also prevents rotation of the inner casing. These elements are essentially of the same type as described in connection with the bearing 26.

Referring to FIG. 6, reference numeral 140 denotes a starting interlock which reacts to the axial position of the inner casing 66 and thus to that of the rotating grinding members. By this interlock the motor 22 is prevented from starting unless the grinding discs are separated.

While one more or less specific embodiment of the invention has been shown and described, it is to be understood that this is for purpose of illustration only, and

that the invention is not to be limited thereby, but its scope is to be determined by the appended claims.

What we claim is:

1. A grinding apparatus for treating fibrous material comprising, a frame, a housing disposed in said frame, two grinding members disposed in said housing, one of said grinding members being secured in said housing and the other mounted on a rotatable shaft passing through said housing and mounted on either side of said housing on bearings carried by said frame, and compressing members adapted to create a grinding pressure between said grinding members, characterized in that said housing is secured to said frame at its end facing said compressing members for transmitting the tensile load between the housing and frame, the opposite end of the housing being mounted on a support permitting axial movement of the housing relative to the frame with the center position remaining practically unchanged, said support being rigidly secured to said housing as well as to said frame and having ample radial extension between its points of securement so as to be adapted on an axial displacement of the housing to perform a swinging movement about its point of securement to the frame.

2. A grinding apparatus for treating fibrous material comprising, a frame, a housing disposed in said frame,

two grinding members disposed in said housing, one of said grinding members being secured in said housing and the other mounted on a rotatable shaft passing through said housing and mounted on either side of said housing on bearings carried by said frame, compression members adapted to create a grinding pressure between said grinding members, characterized in that said housing is secured to said frame at its end facing said compressing members for transmitting the tensile load between the housing and frame, the opposite end of said housing being mounted on a support permitting axial movement of said housing relative to said frame with the center position remaining practically unchanged, at least one of the grinding members consisting of a disk-shaped stator ring and grinding segments carried by it by means of a split seg ment holder, the parts of the segment holder each having a plurality of said grinding segments secured to it, a support ring disposed in the housing and having at its top portion a recess for enabling the grinding segments,- after introduction into the housing, to be threadably secured to the segment holder.

References Cited in the file of this patent UNITED STATES PATENTS