Boring or penetrating the earth – Bit or bit element – Rolling cutter bit or rolling cutter bit element
Patent
1994-07-22
1996-04-16
Neuder, William P.
Boring or penetrating the earth
Bit or bit element
Rolling cutter bit or rolling cutter bit element
29557, E21B 1012
Patent
active
055073557
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention refers to a cutter of a boring head.
This invention deals with cutters both for tunnel boring heads and raise boring heads.
2. Description of Related Art
Prior art roller bearings for cutters of tunnel boring heads, see e.g. U.S. Pat. No. 4,784,438, have usually tapered rollers that are located between an inner and an outer race of the bearing. The circumferential distance between the tapered rollers is controlled by a cage that also is located between the inner and outer races. Since the inner race is stationary, i.e. not rotatable relative to the shaft, said inner race will be subjected to high stresses within a very limited area of its circumference. This means that the inner race will be damaged relatively soon compared to the outer race that rotates relative to the inner race and thus is worn evenly. The consequence of this is that it is favourable to have the inner race as a separate element that is exchangeable when the inner race is worn out. However, there is no need to have the outer race as a separate element since the outer race will normally last for the entire life of the cutter.
The same type of roller bearing is also knowh for raise boring cutters, see e.g. U.S. Pat. No. 4,509,607. In principle the same disadvantages apply as in a cutter or tunnel boring.
SUMMARY AND OBJECTS
An aim of the present invention is to disclose a cutter that has a considerably increased load bearing capacity and a longer life without demanding more room for the roller bearing. The aim of the present invention is realized by a cutter that has been given the characteristics of the appending claims.
The present invention refers to a cutter of a boring head, said cutter being rotatably mounted, via a shaft of the cutter, in a saddle secured to the boring head, a roller bearing means being located between the shaft and a hub, means for axially locking the roller bearing means relative to the shaft and sealing arrangements between the hub and the locking means, said roller bearing means including at least one inner race that is mounted on the shaft and a set of tapered rollers mounted in an outer circumferential recess of the inner race, said hub being rotatable relative to the shaft via said roller bearing means, said rotatable hub carrying rock working means. The invention also refers to a hub per se and a method of manufacturing a hub.
BRIEF DESCRIPTION OF THE DRAWINGS
Below two embodiments of a cutter according to the present invention are described, reference being made to the accompanying drawings, where
FIG. 1 shows a partially sectioned view of a cutter for tunnel boring according to the present invention; and
FIG. 2 shows a partially sectioned view of a cutter for raise boring according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The cutter 10 in FIG. 1 includes a shaft 11 having a longitudinal centre axis 11a. Said shaft 11 is mounted in a saddle (not shown), said saddle being fixed to the boring head (not shown). Two tapered roller bearings are mounted on the shaft 11. Each bearing includes an inner race 12 that is mounted on the shaft 11 by shrink fit. Along its outer periphery the inner race 12 has a recessed path 13. Between the inner races 12 a distance ring 14 is mounted on the shaft 11.
A set of tapered rollers 15 is mounted in the recessed path 13 of each inner race 12. As is evident from FIG. 1 the tapered rollers 15 have their ends with the smallest diameter directed towards each other.
A cage 16 is mounted outside of each set of tapered rollers 15 to control the circumferential distance between the tapered rollers 15. The inner race 12, the tapered rollers 15 and the cage 16 are normally delivered as assembled bearing units. However, it is also possible that the inner race 12 and the tapered rollers 15 are delivered separately, i.e. the tapered rollers 15 are mounted in-situ in the inner race 12. In such a case it is possible to omit the cage 16.
In order to achieve true rolling the exte
REFERENCES:
patent: 3216513 (1965-11-01), Robbins et al.
patent: 3449024 (1969-06-01), Lichte
patent: 4255000 (1981-03-01), Olschewski et al.
patent: 4509607 (1985-04-01), Saxman et al.
patent: 4784438 (1988-11-01), Fikse
patent: 5181577 (1993-01-01), Tsukamoto et al.
Neuder William P.
Sandvik AB
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