US2787426A

US2787426A - Securing means for crusher head to gyratory shaft, including an internally threaded nut shrink fitted to main shaft of crusher

Info

Publication number: US2787426A
Application number: US496727A
Authority: US
Inventors: Alexander J Roubal
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1955-03-25
Filing date: 1955-03-25
Publication date: 1957-04-02
Anticipated expiration: 1974-04-02

Description

Apnl 2, 1957 A. J. ROUBAL 2,787,426

sscuamc MEANS FOR CRUSHER HEAD TO GYRATORY SHAFT, momma AN INTERNALLY THREADED NUT SHRINK FITTED TO MAIN SHAFT OF CRUSHER Filed March 25, 1955 w fze 9 23 2/ 2J Alexander 5. Roubal, Milwaukee, Wis., assignor to Allis- Clralmers Manufacturing Company, Milwaukee, Wis.

Application March 25, 1955, Serial No. 496,727

2 Claims. (Cl. 241-293) This invention relates to gyratory crushers and relates particularly to an improvement in head nuts of the type used for securing the head of the crusher to the main shaft of the crusher.

In gyratory crushers the main shaft thereof is provided with a tapered portion for receiving the crusher head. A threaded section on the shaft above the tapered portion is normally provided for receiving a head nut which functions to force the head downwardly onto the tapered portion of the shaft. When the crusher is assembled, the head nut is forcibly tightened against the top of the head and suitable pinning means for keying the head nut to the head are provided for preventing relative rotational movement between the head nut and the head.

The crusher head may comprise only one piece which fits on the tapered portion of the shaft. In some constructions, however, the head may comprise a head center which fits the tapered portion of the shaft and a head mantle adapted to be fitted on the head center. The present invention is applicable for either of these constructions.

For convenience, only the construction in which the head comprises a head center and a mantle will be referred to in this introduction. it will be understood, however, that the following description of the action of the mantle relative to the head center upon which it is mounted is generally the same as the action of a one piece head, if such construction is utilized, relative to the tapered portion of the shaft upon which the head is mounted.

During operation of the crusher, the crushing surface of the mantle is subjected to a hannnering action by repeated impact of the rock or other material being crushed. This hammering action causes the crushing surface of the mantle to be peened such that the surface layer 'tends to expand by cold working. The cold working causes the mantle to expand radially and the inside diameter of the mantle accordingly expands relative to and away from the head center upon which it is mounted. The radial expansion of the mantle, due to the cold working, is not always uniform and quite often it is the upper part of the mantle which expands the most. In such case a condition occurs in which the mantle fits tightly at the bottom and loosely at the top and, during operation of the crusher, there is a pronounced lateral movement or wobble of the mantle relative to the head nut with which it is in contact. This movement of the upper part of the mantle causes tremendous shocks and jars to be transmitted to the head nut and as a result, the threaded section of the shaft with which the head nut is engaged in time becomes badly damaged.

The damaging of the threaded section of the main shaft of a gyratory crusher is a very serious and costly problem to the owner of the crusher because the threaded section can be repaired only by removing the shaft, which may weigh several tons, from the crusher.

In general the present invention overcomes the problem described by providing a head nut assembly comted States Patent 9 i 2,787,426 Patented Apr. 2, 1957 prising two nuts, one nut being shrink fitted to the shaft of the crusher. The other nut threadedly engages the first nut and engages the head or mantle of the crusher in force transmitting relation.

An object of the invention is to provide a new and im proved head nut assembly for a gyratory crusher. Another object is to provide such a head nut assembly with features of construction operative to withstand shocks and jars imparted thereto without there being any working or play between the crusher shaft and the part of the head nut assembly attached thereto.

Another object of the invention is to provide a new and improved gyratory crusher head nut assembly which withstands shocks and jars imparted thereto without causing damage to the threaded section of the crusher shaft to which the head nut assembly is attached.

Another object is to provide a new and improved gyratory crusher head nut assembly which is attachable to a crusher main shaft which is not provided with keyways, bores or other specially machined shapes to facilitate the attachment of the head nut assembly to the shaft.

Another object of the invention is to provide a new and improved method of joining internally and externally threaded members to provide a very tight threaded engagement fit between the members.

Other objects and advantages will appear from the accompanying drawing and the following detailed description of two embodiments of the invention and a method for performing the invention.

In the drawing:

Fig. 1 is a sectional elevation of a gyratory crusher having a head nut embodied therein in accordance with the present invention;

Fig. 2 is an enlarged fragmentary sectional view corresponding to a portion of Fig. 1 and showing the details of the crusher head nut; and

Fig. 3 is a fragmentary, sectional view of a modification of the head nut arrangement shown in Figs. 1 and 2.

Referring to Fig. 1 of the drawing, there is shown a gyratory crusher of a type known to the art comprising a lower frame 10 provided with a hub portion 11, an upper frame 12 forming the outer shell of the crusher chamber, a spider 13 mounted on upper frame 12, and a centrally located gyratable shaft 14 having the usual tapered portion 15. Shaft 14 is suspended at the upper end thereof by a device 19 mounted in spider 13 and is rotatably fulcrumed in a universal type bearing 20 mounted in spider 13. Shaft 14 is gyrated at its lower end by an actuating eccentric sleeve 21 in which the lower end of shaft 14 is rotatably journaled. Eccentric sleeve 21 has a cylindrical external surface journaled in the hub portion 11 of lower frame 10 and the internal bore of sleeve 21 is eccentric to and has its axis inclined relative to the external surface of sleeve 21. Eccentric sleeve 21 is rotatably supported by a bearing 22 on lower frame 10 and carries a ring gear 23 which is driven by a driving pinion 24. Pinion 24 is mounted on a horizontally disposed shaft 25 which is rotatably mounted in the lower frame 10 and equipped with a driven actuating pulley 26 or the like.

Secured within upper frame 12 is an outer crusher member or concave 30. A frusto-conical crusher member or head 31 is secured to shaft 14 and is spaced from concave 30 to form a crushing chamber 32 therebe tween. Head 31 as illustrated herein comprises a head center 35 adapted to fit the tapered portion 15 of shaft 14, a head mantle 36 adapted to be fitted on head center 35, and a layer 37 of relatively soft metal filling such as zinc or lead disposed between the head center and the head mantle. The head 31 may consist of only one part, however, as it often is in practice. If the invention is applied to a one piece head, a layer of soft metal filling may or may not be disposed between the head and the tapered portion of the shaft, as desired.

The term head as used in the appended claims is intended to cover any type of crusher head which is fitted on the tapered portion of the main shaft 14 regardless of whether the head comprises only one or a plurality of parts.

Referring to Fig. 1 and specifically to Fig. 2, a threaded section 40 is provided on shaft 14 above the tapered portion 15 for receiving a head nut assembly 41. Head nut assembly 41, which functions to secure head 31 to the tapered portion 15 of shaft 14, comprises two parts. One part is an internally and externally threaded nut 42 which threadedly engages threaded section 40 of shaft 14. The second part is an internally threaded nut 43 which threadedly engages nut 42 and has a lower surface 44 which engages the upper surface of crusher head 31 in force transmitting relation.

In accordance with the invention, a shrink fit engagement is provided between nut 42 and shaft 14. In the embodiment of the invention shown in Figs. 1 and 2, the threaded section 40 of shaft 14 is machined so that the pitch diameter thereof is at least equal to the pitch diameter of the internal threads of nut 42 at room temperature. A temperature differential is then created between threaded section 40 of shaft 14 and nut 42, as by heating nut 42 in a furnace or by applying the flame of a ring torch thereto for example, so that the pitch diameter of the internal threads of nut 42 exceed the pitch diameter of the threaded section 40 of shaft 14. During the time the temperature differential referred to is maintained, nut 42 is threaded onto threaded section 40 of shaft 14. When the temperature diiferential is reduced, as by allowing nut 42 to cool to room temperature, nut 42 contracts radially relative to shaft 14 so as to effect a shrink fit engagement between nut 42 and the threaded section 40 of shaft 14.

After nut 42 is secured to shaft 14, nut 43 is tightened against the top of the head mantle 36 and pins 52 are utilized to key nut 43 to the head mantle.

With the above described construction the shocks and jars imparted to nuts 42 and 43 when the mantle 36 moves laterally relative to nuts 42 and 43, as explained above, will not cause injury to the threaded section 40 of shaft 14 because not 42 is shrink fitted on the threaded section of the shaft. Nut 42 fits tightly around shaft 14 by virtue of the shrink fit so that there is little or no play therebeween. As a result the shocks and jars imparted to nut 42 by mantle 36 are withstood to the extent that no working or relative movement, which would cause injury to the threaded section 40 of shaft 14, occurs between shaft 14 and nut 42.

In time the shocks and jars imparted to nut 43 will damage the external threads of nut 42 and internal threads of nut 43. Nuts 42 and 43 can be replaced without removing shaft 14 from the crusher, however, and such a repair job is much cheaper and less troublesome than the job of removing the shaft from the crusher to repair damage done to the threaded section 40 of shaft 14.

Referring to Fig. 3, there is shown a modification of the head nut assembly shown in Figs. 1 and 2. In the modification, the shaft 214 is provided with a smooth surface section instead of a threaded section above tapered portion 215 of the shaft. An advantage of this construction in which screw threads, keyways, bores and 4 the results of other machining operations are eliminated or omitted is that the shaft is correspondingly stronger if it is not subjected to such machining operations.

Head nut assembly 241 comprises two parts. One part is an externally threaded nut 242 having a smooth surface bore which is shrink fitted onto shaft 214. The second part is an internally threaded nut 243 which threadedly engages nut 242 and has a lower surface 244 which engages the upper surface of crusher head 231 in force transmitting relation.

In the specification and claims the term bore, as used in connection with the nuts which comprise the two head nut assemblies illustrated, merely designates the central hole of a nut whether threaded or unthreaded. The terminology threaded bore is used to indicate that the hole is threaded and the terminology smooth surface bore is used to indicate that the hole is not threaded.

While a method for performing the invention and two specific embodiments of the invention have been de scribed for the purpose of illustration, it is to be understood that the invention is not restricted to the exact details shown and described since various modifications within the scope of the claims may occur to persons skilled in the art to which the invention pertains.

It is claimed and desired to secure by Letters Patent:

1. In a gyratory crusher, a shaft having a tapered portion and a threaded section adjacent the tapered portion, an externally tapered head center having a tapered internal bore operably engaging the tapered portion of said shaft, a mantle having a tapered internal bore surrounding said head center and having an annular end surface, a' layer of relatively soft metal filling disposed between said head center and said mantle, an internally and external'ly threaded nut having the internal threads thereof in shrink fit engagement with said threaded section of said shaft and being axially spaced from said head center and said mantle, and an internally threaded nut threadedly engaging the external threads of the other nut and engaging said annular end surface of said mantle in axial force transmitting relation.

2. In a gyratory crusher, a shaft with a tapered portion and a threaded section adjacent the tapered portion, a crusher head having a tapered internal bore operably engaging the tapered portion of said shaft and having an annular end surface, an internally and externally threaded nut having the internal threads thereof in shrink fit engagement with said threaded section of said shaft and being axially spaced from said head, and an internally threaded nut threadedly engaging the external threads of the other nut and engaging said annular surface of said head in axial force transmitting relation.

References Cited in the file of this patent UNITED STATES PATENTS 321,241 Pauly June 30, 1885 594,972 Smith Dec. 7, 1897 1,310,798 Kennedy July 22, 1919 1,985,098 Kennedy Dec. 18, 1934 2,159,272 Kennedy May 23, 1939 2,274,458 Peterson et a1. Feb. 24, 1942 FOREIGN PATENTS 9,109 Great Britain June 21, 1915 726,607 Great Britain Mar. 23, 1955