Excavating – Digging edge – Tooth or adaptor
Reexamination Certificate
2001-01-03
2001-11-27
Novosad, Christopher J. (Department: 3671)
Excavating
Digging edge
Tooth or adaptor
Reexamination Certificate
active
06321471
ABSTRACT:
The present invention is intended to disclose a device for coupling excavator teeth of the type used on excavating machines and the like, that is to say, machines intended to remove masses of earth and stones in public and civil engineering works.
For the removal of masses of earth and stones in civil engineering works of all types, excavating machines of different types are traditionally used which comprise buckets equipped with working edges which are those intended to engage in the mass of earth and stones for their removal. For this reason, there are problems of accelerated wear of the cutting edge, which has to be provided with very hard, detachable members having a high mechanical strength which are the so-called “teeth”. The said teeth are produced from materials having a high degree of hardness and mechanical strength, in order to obtain a more extended working life, and need to be exchanged easily, since their purpose is precisely that of bearing the wear of the working area, so that it is essential for their exchange to be easy and rapid.
The teeth or excavators and the like have to fulfill a series of conditions which in some cases are contradictory and which represent on the one hand reduced manufacturing costs given the type of application for which they are to be used and the frequency of their renewal, and on the other hand high strength and the most extended life possible.
The harmonization of this combination of characteristics is not easy in devices for coupling excavator teeth since, firstly, owing to the fact that they need to be low-cost mass-produced articles, it is not possible to have recourse to mechanization of the parts in order to obtain more or less narrow tolerances in their dimensions, so that it is necessary to carry out their manufacture on the basis of economical production methods for obtaining solid parts, such as casting and forging. However, the use of cast or forged parts represents an important limitation in the dimensional tolerances which can be obtained on the excavator teeth, resulting in limitations to good coupling between the tooth and the so-called tooth-carrier, which is the element for connection with the active edge of the bucket of the excavator. A result of the said unsatisfactory coupling is the occurrence of different operational problems due to incorrect fitting of the tooth in the tooth-carrier, which manifests itself in high local contact pressures with the consequent wear and increase in the coupling play between the tooth and the tooth-carrier, which in turn accelerates the problems of wear and leads to a reduction in the useful life of the coupling.
For the technical reasons mentioned above, one of the permanent problems in the manufacture of teeth for excavators lies in obtaining designs which make it possible to achieve improvements in the coupling of the tooth to the tooth-carrier without this meaning an excessive increase in the difficulties of manufacture and therefore in the cost of said parts. For this reason, numerous systems for coupling the tooth to the tooth-carrier have been disclosed, all of which claim to introduce improvements in the design of the parts and therefore in the coupling of the latter.
U.S. Pat. No. 4,404,760 discloses a coupling with an adapter and a point element in which the adapter has a recess with ears and a nose portion which develop from a conical form to a free rectangular end.
The present invention has ears, which have a support function as they are capable of absorbing efforts transmitting the same from the end of the point to the adapter.
The coupling of the present invention is precisely the result of the work carried out by the inventors in order to obtain a more balanced solution to the technical problems which arise on the teeth of the excavators. The result of the investigations and work performed by the inventors is that of obtaining a device for coupling excavator teeth which combines in a satisfactory manner the characteristics of mechanical robustness necessary in the part with significant ease of manufacture and with an extended life of the coupling.
According to the present invention, the satisfactory results thereof are obtained by means of a specific combination of elements for guiding and coupling the teeth in the tooth-carrier, which combination consists in: coupling by interposing special projections of the teeth which are equipped with a double, stepped internal guide, with complementary recesses of the toothcarrier, mutual coupling in areas of revolution symmetrical to the coupling, and finally male/female coupling in a terminal prismatic area. The combination of these three types of principal coupling is obtained by producing a first area of coupling between tooth and tooth-carrier which comprises seatings which open on the edge of the tooth-carrier and which have internally a double straight guide which assumes the form of a profile which has in cross-section a double straight stepped region and which extends through the sides of the tooth-carrier parallel to the axis of the part. The tooth has projecting areas complementary to the said parts having a double stepped guide structure, so that, after their introduction, the aforesaid projecting areas are properly engaged in the double guide recesses, providing multiple areas of coupling between the tooth and the tooth-carrier in a transverse arrangement at 90° which provide a very effective coupling with many areas of contact between the two parts. The immediate area of coupling between tooth and tooth-carrier has symmetrical revolution surfaces opposed to one another, assuming the form of areas of cylindrical or frustoconical surfaces, arranged on the start of the tooth coupling rod intended to coincide in the complementary opening of the tooth-carrier and, preferably, in an arrangement such that one of the revolution surfaces is arranged on the upper portion of the part and the other, symmetrically opposed to the first, is arranged on the lower portion of the part. The third area of coupling between tooth and tooth-carrier, combined with those described above, constitutes a terminal journal of the coupling projection of the tooth, which assumes a prismatic structure with the edges rounded and the axis of which coincides with the axis of the part. The tooth has a coupling opening the structure of which is complementary to that of the tooth-carrier, there being obtained by means of the combination of the three separate areas of coupling which have been mentioned a very effective coupling between the tooth and the tooth-carrier which, without altering the favourable characteristics of manufacture by means of casting or forging, permits effective guiding of both parts with respect to each other, with the result that the areas of contact between tooth and tooth-carrier are significantly increased, which leads to less individual wear and therefore a more extended life of the coupling.
These improvements likewise provide for the arrangement of the seating of the bolt or cotter pin in the body or portion of the tooth-carrier which is not covered by the tooth, making it possible to increase the strength of the tooth-carrier, which in turn makes it possible to reduce the said tooth-carrier internally, reducing the weight of the assembly. The upper and lower ends of the seating for the retaining pin or bolt will optionally be closed by means of covers intended to preserve the seating of the cotter pin as far as possible, facilitating its subsequent disassembly at the right moment. The retaining bolt or pin will have a structure consisting of a base body carrying a centering extension which is joined to the base body by vulcanization. In order to permit the inspection of the correctly introduced state of the cotter pin and likewise certain manipulations which may be necessary for extraction, the tooth will have in one of its lateral fitting lugs an opening which coincides with the position of the bolt.
The constitution of the assembly of tooth and tooth-carrier may be symmetrical or asymmetrical with respect to the male
Fernandez Muñoz Roberto
Laforet Alvarez Jose Antonio
Navarro Romero Lorenzo
Perez Soria Francisco
Darby & Darby
Metalogenia S.A.
Novosad Christopher J.
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