ADAPTER AND WEAR ELEMENT WITH A PIN ARRANGED AT A LOW STRESS POINT

Abstract

The invention relates to an adapter and a wear element of a shovel of an earth moving machine attached to one another by means of a pin, wherein the pin is positioned at a point such that, as there is relative rotation between the wear element and the adapter, due to the application of both a force according to direction Y applied on a point B1 and directed towards a point B2 and a force according to direction Y applied on point B2 and directed towards point B1, the support surfaces of the adapter and of the wear element contact one another before the pin is subjected to stresses. The stresses the pin must withstand are thereby reduced.

Claims

1. An adapter for supporting a wear element of a shovel of an earth moving machine, comprising: said adapter has a rear part suitable for being fixed to said shovel, and a front part suitable for being housed inside a cavity of said wear element, wherein said adapter defines a longitudinal axis X, has at least one pin opening suitable for housing a pin suitable for retaining said wear element on said adapter, wherein said pin has a pre-established location with respect to said pin opening and has a longitudinal axis defining an axis Z, wherein said axis X and said axis Z define a plane XZ and a direction perpendicular to said plane XZ, defining an axis Y, and said axis X and said axis Y define a plane XY, has at least one front upper support surface, at least one rear upper support surface, at least one front lower support surface, and at least one rear lower support surface, said upper support surfaces and said lower support surfaces are symmetrical to one another with respect to said plane XZ, in a longitudinal section according to plane XY, the following is defined: a point A1 which is the rear end of the intersection of the rear upper support surface with said plane XY or, if there is more than one rear upper support surface, it is the projection according to Z on said plane XY of the most rearward end of all the rear upper support surfaces, a point A2 which is the rear end of the intersection of the rear lower support surface with said plane XY or, if there is more than one rear lower support surface, it is the projection according to Z on said plane XY of the most rearward end of all the rear lower support surfaces, a point B1 which is the front end of the intersection of the front upper support surface with said plane XY or, if there is more than one front upper support surface, it is the projection according to Z on said plane XY of the most forward end of all the front upper support surfaces, a point B2 which is the front end of the intersection of the front lower support surface with said plane XY or, if there is more than one front lower support surface, it is the projection according to Z on said plane XY of the most forward end of all the front lower support surfaces, wherein between A1 and A2 there is a distance H2 in direction Y, and between B1 and B2 there is a distance H1 in direction Y, wherein when said wear element is assembled on said adapter, there is a clearance, in the direction of axis Y, between any of said points A1, A2, B1, and B2 and said wear element with a predetermined value j, wherein between A1 and B1 there is a distance D in direction X, wherein said axis Z passes through the inside of a circle arranged in said longitudinal section, with radius R and center C, wherein said center C is arranged on said axis X, wherein R2 is a radius with an origin at center C and end at A1, wherein A1j is a point arranged at a distance R2 from center C and at a distance from axis X, according to the direction of Y, equal to $\frac{H2}{2}+j,$ wherein R1 is a radius with an origin at center C and end at B1, wherein B1j is a point arranged at a distance R1 from center C and at a distance from axis X, according to the direction of Y, equal to $\frac{H1}{2}+j,$ wherein between A1 and C there is a distance A in direction X, and between B1 and C there is a distance B in direction X, and wherein if said adapter is for a wear element without lugs $\arcsin \left(\begin{array}{c}H1/2+j\\ R1\end{array}\right)\arcsin \left(\begin{array}{c}H1/2\\ R1\end{array}\right)-\arcsin \left(\begin{array}{c}H2/2+j\\ R2\end{array}\right)\arcsin \left(\begin{array}{c}H2/2\\ R2\end{array}\right)$ whereas if said adapter is for a wear element with lugs $\arcsin \left(\frac{H1/2+j}{R1}\right)-\arcsin \left(\frac{H1/2}{R1}\right)=\arcsin \left(\frac{H2/2}{R2}\right)-\arcsin \left(\frac{H2/2-j}{R2}\right)$

2. The adapter according to claim 1, wherein said radius R has a value less than 10% of the sum of distances A and B, and preferably has a value less than 5% of the sum of distances A and B.

3. The adapter according to claim 1, wherein a hemispherical surface with center C and radius R1 extends between [a] the front end of the front upper support surface or, if there is more than one front upper support surface, between the front most forward end of all the front upper support surfaces, and [b] the front end of the front lower support surface or, if there is more than one front lower support surface, between the front most forward end of all the front lower support surfaces.

4. The adapter according to claim 1, wherein said adapter comprises at least one upper secondary hemispherical surface, the center of which is at C, and one lower secondary hemispherical surface, the center of which is also at C.

5. The adapter according to claim 1, wherein said adapter is for a wear element without lugs.

6. The adapter according to claim 5, wherein H2 is greater than H1.

7. A wear element suitable for being assembled on an adapter of a shovel of an earth moving machine comprising: said wear element has a front part suitable for cutting into the earth to be moved, and a rear part with a cavity suitable for housing therein a front part of said adapter, wherein said wear element defines a longitudinal axis X, has at least one through opening on one side of said cavity, suitable for housing a pin suitable for retaining said wear element on said adapter, wherein said pin has a pre-established location with respect to said through opening and has a longitudinal axis defining an axis Z, wherein said axis X and said axis Z define a plane XZ and a direction perpendicular to said plane XZ, defining an axis Y, and said axis X and said axis Y define a plane XY, has at least one front upper support surface, at least one rear upper support surface, at least one front lower support surface, and at least one rear lower support surface, said upper support surfaces and said lower support surfaces are symmetrical to one another with respect to said plane XZ, in a longitudinal section according to plane XY, the following is defined: a point a1 which is the rear end of the intersection of the rear upper support surface with said plane XY or, if there is more than one rear upper support surface, it is the projection according to Z on said plane XY of the most rearward end of all the rear upper support surfaces, a point a2 which is the rear end of the intersection of the rear lower support surface with said plane XY or, if there is more than one rear lower support surface, it is the projection according to Z on said plane XY of the most rearward end of all the rear lower support surfaces, a point b1 which is the front end of the intersection of the front upper support surface with said plane XY or, if there is more than one front upper support surface, it is the projection according to Z on said plane XY of the most forward end of all the front upper support surfaces, a point b2 which is the front end of the intersection of the front lower support surface with said plane XY or, if there is more than one front lower support surface, it is the projection according to Z on said plane XY of the most forward end of all the front lower support surfaces, wherein between a1 and a2 there is a distance h2 in direction Y, and between b1 and b2 there is a distance h1 in direction Y, wherein when said wear element is assembled on said adapter, there is a clearance, in the direction of axis Y, between any of said points a1, a2, b1, and b2 and said adapter with a predetermined value j, wherein between a1 and b1 there is a distance d in direction X, wherein said axis Z passes through the inside of a circle arranged in said longitudinal section, with radius r and center c, wherein said center c is arranged on said axis X, wherein r2 is a radius with an origin at center c and end at a1, wherein a1j is a point arranged at a distance r2 from center c and at a distance from axis X, according to the direction of Y, equal to $\frac{h2}{2}-j,$ wherein r1 is a radius with an origin at center c and end at b1, wherein b1j is a point arranged at a distance r1 from center c and at a distance from axis X, according to the direction of Y, equal to $\frac{h1}{2}-j,$ wherein between a1 and c there is a distance a in direction X, and between b1 and c there is a distance b in direction X, and wherein if said wear element is a wear element without lugs $\mathrm{arc}\sin \left(\frac{h1/2}{r1}\right)-\mathrm{arc}\sin \left(\frac{h1/2-j}{r1}\right)=\mathrm{arc}\sin \left(\frac{h2/2}{r2}\right)-\mathrm{arc}\sin \left(\frac{h2/2-j}{r2}\right)$ whereas if said wear element is a wear element with lugs $\mathrm{arc}\sin \left(\frac{h1/2}{r1}\right)-\mathrm{arc}\sin \left(\frac{h1/2-j}{r1}\right)=\mathrm{arc}\sin \left(\frac{h2/2+j}{r2}\right)-\mathrm{arc}\sin \left(\frac{h2/2}{r2}\right).$

8. The wear element according to claim 7, wherein said radius r has a value less than 10% of the sum of distances a and b, and preferably has a value less than 5% of the sum of distances a and b.

9. The wear element according to claim 7, wherein a hemispherical surface with center c and radius r1 extends between [a] the front end of the front upper support surface or, if there is more than one front upper support surface, between the front most forward end of all the front upper support surfaces, and [b] the front end of the front lower support surface or, if there is more than one front lower support surface, between the front most forward end of all the front lower support surfaces.

10. The wear element according to claim 7, wherein said wear element comprises at least one upper secondary hemispherical surface the center of which is at c, and one lower secondary hemispherical surface, the center of which is also at c.

11. The wear element according to claim 7, wherein said wear element is a wear element without lugs.

12. The wear element according to claim 11, wherein h2 is greater than h1.

13. An assembly formed by an adapter according to claim 1 and a wear element suitable for being assembled on an adapter of a shovel of an earth moving machine comprising: said wear element has a front part suitable for cutting into the earth to be moved, and a rear part with a cavity suitable for housing therein a front part of said adapter, wherein said wear element defines a longitudinal axis X, has at least one through opening on one side of said cavity, suitable for housing a pin suitable for retaining said wear element on said adapter, wherein said pin has a pre-established location with respect to said through opening and has a longitudinal axis defining an axis Z, wherein said axis X and said axis Z define a plane XZ and a direction perpendicular to said plane XZ, defining an axis Y, and said axis X and said axis Y define a plane XY, has at least one front upper support surface, at least one rear upper support surface, at least one front lower support surface, and at least one rear lower support surface, said upper support surfaces and said lower support surfaces are symmetrical to one another with respect to said plane XZ, in a longitudinal section according to plane XY, the following is defined: a point a1 which is the rear end of the intersection of the rear upper support surface with said plane XY or, if there is more than one rear upper support surface, it is the projection according to Z on said plane XY of the most rearward end of all the rear upper support surfaces, a point a2 which is the rear end of the intersection of the rear lower support surface with said plane XY or, if there is more than one rear lower support surface, it is the projection according to Z on said plane XY of the most rearward end of all the rear lower support surfaces, a point b1 which is the front end of the intersection of the front upper support surface with said plane XY or, if there is more than one front upper support surface, it is the projection according to Z on said plane XY of the most forward end of all the front upper support surfaces, a point b2 which is the front end of the intersection of the front lower support surface with said plane XY or, if there is more than one front lower support surface, it is the projection according to Z on said plane XY of the most forward end of all the front lower support surfaces, wherein between a1 and a2 there is a distance h2 in direction Y, and between b1 and b2 there is a distance h1 in direction Y, wherein when said wear element is assembled on said adapter, there is a clearance, in the direction of axis Y, between any of said points a1, a2, b1, and b2 and said adapter with a predetermined value j, wherein between a1 and b1 there is a distance d in direction X, wherein said axis Z passes through the inside of a circle arranged in said longitudinal section, with radius r and center c, wherein said center c is arranged on said axis X, wherein r2 is a radius with an origin at center c and end at a1, wherein a1j is a point arranged at a distance r2 from center c and at a distance from axis X, according to the direction of Y, equal to h2/2−j: wherein r1 is a radius with an origin at center c and end at b1, wherein b1j is a point arranged at a distance r1 from center c and at a distance from axis X, according to the direction of Y, equal to $\frac{h1}{2}-j,$ wherein between a1 and c there is a distance a in direction X, and between b1 and c there is a distance b in direction X, and wherein if said wear element is a wear element without lugs $\mathrm{arc}\sin \left(\frac{h1/2}{r1}\right)-\mathrm{arc}\sin \left(\frac{h1/2-j}{r1}\right)=\mathrm{arc}\sin \left(\frac{h2/2}{r2}\right)-\mathrm{arc}\sin \left(\frac{h2/2-j}{r2}\right)$ whereas if said wear element is a wear element with lugs $\mathrm{arc}\sin \left(\frac{h1/2}{r1}\right)-\mathrm{arc}\sin \left(\frac{h1/2-j}{r1}\right)=\mathrm{arc}\sin \left(\frac{h2/2+j}{r2}\right)-\mathrm{arc}\sin \left(\frac{h2/2}{r2}\right).$

14. The assembly according to claim 13, wherein the value of radius R1 is equal to the value of radius r1.

15. A method of designing an adapter for supporting a wear element of a shovel of an earth moving machine, wherein: said adapter has a rear part suitable for being fixed to said shovel, and a front part suitable for being housed inside a cavity of said wear element, wherein said adapter defines a longitudinal axis X, said method comprising a step of locating at least one pin opening suitable for housing a pin suitable for retaining said wear element on said adapter, wherein said pin has a longitudinal axis defining an axis Z, wherein said axis X and said axis Z define a plane XZ and a direction perpendicular to said plane XZ, defining an axis Y, and said axis X and said axis Y define a plane XY, wherein said adapter has at least one front upper support surface, at least one rear upper support surface, at least one front lower support surface, and at least one rear lower support surface, wherein said upper support surfaces and said lower support surfaces are symmetrical to one another with respect to said plane XZ, wherein in a longitudinal section according to plane XY, the following is defined: a point A1 which is the rear end of the intersection of the rear upper support surface with said plane XY or, if there is more than one rear upper support surface, it is the projection according to Z on said plane XY of the most rearward end of all the rear upper support surfaces, a point A2 which is the rear end of the intersection of the rear lower support surface with said plane XY or, if there is more than one rear lower support surface, it is the projection according to Z on said plane XY of the most rearward end of all the rear lower support surfaces, a point B1 which is the front end of the intersection of the front upper support surface with said plane XY or, if there is more than one front upper support surface, it is the projection according to Z on said plane XY of the most forward end of all the front upper support surfaces, a point B2 which is the front end of the intersection of the front lower support surface with said plane XY or, if there is more than one front lower support surface, it is the projection according to Z on said plane XY of the most forward end of all the front lower support surfaces, wherein between A1 and A2 there is a distance H2 in direction Y, and between B1 and B2 there is a distance H1 in direction Y, wherein when said wear element is assembled on said adapter, there is a clearance, in the direction of axis Y, between any of said points A1, A2, B1, and B2 and said wear element with a predetermined value j, wherein between A1 and B1 there is a distance D in direction X, and wherein said axis Z is positioned such that it passes through the inside of a circle arranged in said longitudinal section, with radius R and center C, wherein said center C is arranged on said axis X, wherein R2 is a radius with an origin at center C and end at A1, wherein A1j is a point arranged at a distance R2 from center C and at a distance from axis X, according to the direction of Y, equal to $\frac{H2}{2}+j,$ wherein R1 is a radius with an origin at center C and end at B1, wherein B1j is a point arranged at a distance R1 from center C and at a distance from axis X, according to the direction of Y, equal to $\frac{H1}{2}+j,$ wherein between A1 and C there is a distance A in direction X, and between B1 and C there is a distance B in direction X, and wherein if said adapter is for a wear element without lugs $\mathrm{arc}\sin \left(\frac{H1/2+j}{R1}\right)-\mathrm{arc}\sin \left(\frac{H1/2}{R1}\right)=\mathrm{arc}\sin \left(\frac{H2/2+j}{R2}\right)-\mathrm{arc}\sin \left(\frac{H2/2}{R2}\right)$ whereas if said adapter is for a wear element with lugs $\mathrm{arc}\sin \left(\frac{H1/2+j}{R1}\right)-\mathrm{arc}\sin \left(\frac{H1/2}{R1}\right)=\mathrm{arc}\sin \left(\frac{H2/2}{R2}\right)-\mathrm{arc}\sin \left(\frac{H2/2-j}{R2}\right).$

16. A method of manufacturing an adapter for supporting a wear element of a shovel of an earth moving machine, wherein: said adapter has a rear part suitable for being fixed to said shovel, and a front part suitable for being housed inside a cavity of said wear element, wherein said adapter defines a longitudinal axis X, comprising a step of designing an adapter according to claim 15, a step of manufacturing a mold comprising the geometry suitable for forming said pin opening suitable for housing a pin suitable for retaining said wear element on said adapter, wherein said pin has a longitudinal axis defining said axis Z, and a step of pouring molten material into said mold for obtaining said adapter.

17. A method of designing a wear element suitable for being assembled on an adapter of a shovel of an earth moving machine, wherein: said wear element has a front part suitable for cutting into the earth to be moved, and a rear part with a cavity suitable for housing therein a front part of said adapter, wherein said wear element defines a longitudinal axis X, said method comprising a step of locating at least one through opening on one side of said cavity, suitable for housing a pin suitable for retaining said wear element on said adapter, wherein said pin has a longitudinal axis defining an axis Z, wherein said axis X and said axis Z define a plane XZ and a direction perpendicular to said plane XZ, defining an axis Y, and said axis X and said axis Y define a plane XY, wherein said wear element has at least one front upper support surface, at least one rear upper support surface, at least one front lower support surface, and at least one rear lower support surface, wherein said upper support surfaces and said lower support surfaces are symmetrical to one another with respect to said plane XZ, wherein in a longitudinal section according to plane XY, the following is defined: a point a1 which is the rear end of the intersection of the rear upper support surface with said plane XY or, if there is more than one rear upper support surface, it is the projection according to Z on said plane XY of the most rearward end of all the rear upper support surfaces, a point a2 which is the rear end of the intersection of the rear lower support surface with said plane XY or, if there is more than one rear lower support surface, it is the projection according to Z on said plane XY of the most rearward end of all the rear lower support surfaces, a point b1 which is the front end of the intersection of the front upper support surface with said plane XY or, if there is more than one front upper support surface, it is the projection according to Z on said plane XY of the most forward end of all the front upper support surfaces, a point b2 which is the front end of the intersection of the front lower support surface with said plane XY or, if there is more than one front lower support surface, it is the projection according to Z on said plane XY of the most forward end of all the front lower support surfaces, wherein between a1 and a2 there is a distance h2 in direction Y, and between b1 and b2 there is a distance h1 in direction Y, wherein when said wear element is assembled on said adapter, there is a clearance, in the direction of axis Y, between any of said points a1, a2, b1, and b2 and said adapter with a predetermined value j, wherein between a1 and b1 there is a distance d in direction X, and wherein said axis Z is positioned to pass through the inside of a circle arranged in said longitudinal section, with radius r and center c, wherein said center c is arranged on said axis X, wherein r2 is a radius with an origin at center c and end at a1, wherein a1j is a point arranged at a distance r2 from center c and at a distance from axis X, according to the direction of Y, equal to $\frac{h2}{2}-j,$ wherein r1 is a radius with an origin at center c and end at b1, wherein b1j is a point arranged at a distance r1 from center c and at a distance from axis X, according to the direction of Y, equal to $\frac{h1}{2}-j,$ wherein between a1 and c there is a distance a in direction X, and between b1 and c there is a distance b in direction X, and wherein if said wear element is a wear element without lugs $\mathrm{arc}\sin \left(\frac{h1/2}{r1}\right)-\mathrm{arc}\sin \left(\frac{h1/2-j}{r1}\right)=\mathrm{arc}\sin \left(\frac{h2/2}{r2}\right)-\mathrm{arc}\sin \left(\frac{h2/2-j}{r2}\right)$ whereas if said wear element is a wear element with lugs $\mathrm{arc}\sin \left(\frac{h1/2}{r1}\right)-\mathrm{arc}\sin \left(\frac{h1/2-j}{r1}\right)=\mathrm{arc}\sin \left(\frac{h2/2+j}{r2}\right)-\mathrm{arc}\sin \left(\frac{h2/2}{r2}\right).$

18. A method of manufacturing a wear element suitable for being assembled on an adapter of a shovel of an earth moving machine, wherein: said wear element is a wear element without lugs, said wear element has a front part suitable for cutting into the earth to be moved, and a rear part with a cavity suitable for housing therein a front part of said adapter, wherein said wear element defines a longitudinal axis X, comprising a step of designing a wear element according to claim 17, a step of manufacturing a mold comprising the geometry suitable for forming said through opening suitable for housing a pin suitable for retaining said wear element on said adapter, wherein said pin has a longitudinal axis defining said axis Z, and a step of pouring molten material into said mold for obtaining said wear element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0101] Other advantages and features of the invention will become apparent from the following description in which preferred embodiments of the invention are described in a non-limiting manner in reference to the attached drawings. In the figures:

[0102] FIG. 1 shows a perspective view of a wear assembly formed by an adapter, a wear element, and a pin.

[0103] FIGS. 2 to 4 show schematic top plan views of adapters with support surfaces that are marked.

[0104] FIG. 5 shows a schematic view of a section according to plane XY of a wear element.

[0105] FIG. 6 shows a schematic view of a section according to plane XY of the assembly formed by an adapter and a wear element.

[0106] FIG. 7 shows a schematic view of a section according to plane XY of the adapter of FIG. 6, and the movement performed by points B1 and A2 during a rotation.

[0107] FIG. 8 shows a schematic view of a section according to plane XY of a wear element without lugs.

[0108] FIG. 9 shows a schematic side elevational view of a wear element with lugs.

[0109] FIG. 10 shows a schematic side elevational view of an adapter for a wear element with lugs, with points A1, A2, B1, and B2 being marked.

[0110] FIG. 11 shows a schematic side elevational view of a wear element with lugs, with points a1, a2, b1, and b2 being marked.

[0111] FIGS. 12 to 15 show schematic views of sections according to plane XY of four wear assemblies with different fronts.

[0112] FIG. 16 show a top front perspective view of an adapter according to the invention.

[0113] FIG. 17 shows a top rear perspective view of a wear element, specifically a tooth, according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0114] FIG. 1 shows an exploded general view of a wear assembly formed by an adapter 1, a wear element 2 (specifically a tooth, which is a preferred embodiment of the invention), and a pin 3. The adapter 1 has a rear part 4, whereby it is fixed to the shovel of an earth moving machine, and a front part 5, usually referred to as a nose, having a geometry suitable for being housed inside a cavity 10 present in the rear part 6 of the wear element 2. The adapter 1 has a pin opening 8 and the wear element 2 has two through openings 9, each of which goes through one of the walls sides surrounding the cavity 10. The pin opening 8 of the adapter 1 and the through openings 9 of the wear element 2 are arranged such that, in the assembled position of the wear element 2 on the adapter 1, the pin opening 8 and the two through openings 9 are aligned with one another, or at least partially aligned, since they do not necessarily have to have exactly the same cross-section. However, the partial alignment must be sufficient so that, in the assembled position, a pin 3 may be in the pin opening 8 of the adapter 1 and project therefrom, being introduced into the through openings 9 of the wear element 2 by a sufficient amount to enable exerting its locking function.

[0115] The adapter 1 defines a main direction between its front part 5 and its rear part 4. This main direction thus defines a longitudinal axis X. In turn, the pin opening 8 in which the pin 3 will be housed also defines a main direction which is perpendicular to axis X. This second main direction thus defines an axis Z. Both axes define a plane XZ and a direction perpendicular thereto, defining an axis Y.

[0116] The same occurs with the wear element 2: its front part 7 and its rear part 6 define an axis X, the through openings 9 thereof (which are aligned with one another) define an axis Z, and the direction perpendicular to the corresponding plane XZ defines an axis Y. Furthermore, in the assembled position axes XYZ of the adapter 1 and axes XYZ of the wear element 2 coincide.

[0117] In general, the front part 5 of the adapter 1 and the cavity 10 of the wear element 2 have more or less complex geometries. Usually these geometries are designed such that there is not complete contact between the entire surface of the front part 5 of the adapter 1 and the cavity 10, but rather it is envisaged that the contact will be on specific support surfaces clearly defined in the design step. The forces and reactions are transmitted between the adapter 1 and the wear element 2 through these support surfaces. As discussed above, during use of the wear assembly and due to wear, the deformations and the introduction of material between the gaps of the assembly, the actual situation may be more complex, but it is not in contradiction with the fact that both the adapter 1 and the wear element 2 have, as their own characteristic elements, the mentioned support surfaces.

[0118] In regard to the present invention, forces and reactions according to axis Y (or components according to axis Y thereof) are taken into account, so it is of interest to provide support surfaces that are capable of transmitting forces in this direction, even though these surfaces do not have to be completely planar or perfectly oriented such that they are perpendicular to Y. In general, these forces and reactions will tend to cause the wear element 2 to rotate with respect to the adapter 1 around an axis parallel to Z. An upper part (in the top part in FIG. 1) and a lower part as well as a front part (to the left in FIG. 1) and a rear part of both the adapter 1 and the wear element 2 can be defined using this axis Z.

[0119] Both the adapter 1 and the wear element 2 must have at least one front upper support surface, one rear upper support surface, one front lower support surface, and one rear lower support surface. These surfaces can have various geometries, and there may be more than one of them (for example, two rear support surfaces, that is, both the upper and the lower rear support surfaces). FIGS. 2 to 4 show several schematic examples. Adapters seen “from above” (according to direction Y) with upper support surfaces being marked are depicted in a highly schematic manner in these figures. The intersection with a plane XY has also been marked. There may be one or more than one upper support surface in each front and rear area. Naturally, there may be other shapes (the actual shapes are usually more complex) and they can be mixed in any way (for example, the front upper surface of FIG. 2 with the rear upper surfaces of FIG. 4, etc.). The exact same situation may occur in the wear element 2.

[0120] For the present invention, the points which allow defining these support surfaces are also important: [0121] point A1 which is the rear end of the intersection of the rear upper support surface with plane XY or, if there is more than one rear upper support surface, it is the projection according to Z on plane XY of the most rearward end of all the rear upper support surfaces [0122] point B1 which is the front end of the intersection of the front upper support surface with plane XY or, if there is more than one front upper support surface, it is the projection according to Z on plane XY of the most forward end of all the front upper support surfaces.

[0123] Points A2 and B2 arranged in the lower part of the adapter 1 are similarly defined. Likewise, points a1, a2, b1, and b2 of the wear element 2 can similarly be defined.

[0124] FIG. 5 shows a longitudinal section, according to plane XY, of a wear element 2. It has points a1, a2, b1, and b2 marked. These points define distances h1, h2, and d. Distances H1, H2, and D are defined in an equivalent manner for the adapter 1.

[0125] FIG. 6 shows a schematic view of a section according to plane XY of the assembly formed by an adapter 1 and a wear element 2. Points A1, A2, B1, and B2 of the adapter 1 and clearance j have been indicated. Points a1, a2, b1, and b2 of the wear element 2 and clearance j could similarly be depicted.

[0126] When the adapter 1 is subjected to a rotation in the counterclockwise direction with respect to the wear element 2 (assume, for example, that the wear element 2 is driven into the ground and that in an attempt to move the shovel, this rotation of the adapter 1 with respect to the wear element 2 is caused), point B1 will move up to a height j, at which time it will collide with the wear element 2, at point B1j. This upward movement will be along an arc with radius R1 and center C. In turn, point A2 will move down by a height j following an arc with radius R2 and center C until reaching point A2j. Through symmetry (the support surfaces are symmetrical with respect to plane XZ), points B2j and A1j are also present, and point C is known to be at a point of axis X. FIG. 7 shows these elements. Distances A and B are also shown.

[0127] However, according to the invention it is of interest for arc B1CB1j to be equal to arc A2CA2j. The two points will thereby contact one another simultaneously, which will reduce the stresses the pin must withstand. Therefore, the following holds

[00017]$\arcsin \left(\frac{H1/2+j}{R1}\right)-\arcsin \left(\frac{H1/2}{R1}\right)=\arcsin \left(\frac{H2/2}{R2}\right)-\arcsin \left(\frac{H2/2-j}{R2}\right)$

[0128] The most practical way to solve this equation is by iterations.

[0129] The equivalent formula for a wear element 2 can similarly be calculated:

[00018]$\arcsin \left(\frac{h1/2}{r1}\right)-\arcsin \left(\frac{h1/2-j}{r1}\right)=\arcsin \left(\frac{h2/2}{r2}\right)-\arcsin \left(\frac{h2/2-j}{r2}\right)$

[0130] FIGS. 8 and 9 schematically show a wear element 2 without lugs and another one with lugs, respectively. Reactions RE1 and RE2 that occur, and their points of application when a force F is applied at the tip of the wear element 2 are also shown.

[0131] In the case of a wear assembly in which the wear element 2 has lugs, the position of points A1, A2, B1, B2, a1, a2, b1, and b2 is the one shown in FIGS. 10 and 11. Applying the same reasoning as that applied in the case of a wear assembly without lugs leads to the following formulas: [0132] for the adapter 1:

[00019]$\arcsin \left(\frac{H1/2+j}{R1}\right)-\arcsin \left(\frac{H1/2}{R1}\right)=\arcsin \left(\frac{H2/2}{R2}\right)-\arcsin \left(\frac{H2/2-j}{R2}\right)$ [0133] for the wear element 2 with lugs:

[00020]$\arcsin \left(\frac{h1/2}{r1}\right)-\arcsin \left(\frac{h1/2-j}{r1}\right)=\arcsin \left(\frac{h2/2+j}{r2}\right)-\arcsin \left(\frac{h2/2}{r2}\right)$

[0134] Numerical simulations of four wear assemblies have been performed in which the adapter 1 has different surfaces between the front end of the front upper support surface and the front end of the front lower support surface. In each case, the wear element 2 has an equivalent surface inside its cavity 10. In all cases, the clearance j was 0.5 mm and the direct load applied was 10000 N. The following results were obtained:

Frontal Plane (FIG. 12)

[0135] X pin reaction: 7040 N [0136] Y pin reaction: 12845 N [0137] Total pin reaction: 14648 N [0138] Reaction/load: 146% [0139] X reaction/load: 70%

Symmetrical Angled Front (FIG. 13)

[0140] X pin reaction: 3127 N [0141] Y pin reaction: 14068 N [0142] Total pin reaction: 14411 N [0143] Total reaction/load: 144% [0144] X reaction/load: 31%

Rounded Front (FIG. 14)

[0145] X pin reaction: 4698 N [0146] Y pin reaction: 12475 N [0147] Total pin reaction: 13330 N [0148] Reaction/load: 133% [0149] X reaction/load: 47%
Front with Hemispherical Surface (11, 12) with Center C (Coinciding with Center c) and Radius R1 (Equal to r1) (FIG. 15) [0150] X pin reaction: 2362 N [0151] Y pin reaction: 14073 N [0152] Total pin reaction: 14270 N [0153] Reaction/load: 143% [0154] X reaction/load: 24%

[0155] It can be observed that the flat front surface (FIG. 12) is the least favorable of all. In turn, the hemispherical front surface (11, 12) has the smallest reaction according to axis X.

[0156] FIG. 16 shows an adapter 1 according to the invention. The areas corresponding to the front upper support surface (having only one C-shaped surface) and to the rear upper support surfaces (having two, one on each side of the adapter) have been marked with shading. FIG. 17 shows a wear element 2 (namely, a tooth), suitable for being assembled in the adapter 1 of FIG. 16. The front lower support surface and the lower rear support surfaces of the tooth 2 can be observed in the cavity 10 of the tooth 2 (also shaded). The tooth 2 of FIG. 17 is a tooth without lugs and it can be seen that h2 is greater than h1. Similarly, in the adapter H2 is greater than H1. In the adapter 1, a hemispherical surface 11 with center C and radius R1 extends between the front end of the front upper support surface and the front end of the front lower support surface. In turn, in the tooth 2 a hemispherical surface 12 with center c and radius r1 extends between the front end of the front upper support surface and the front end of the front lower support surface. Both radii R1 and r1 are identical, and when the tooth 2 is assembled on the adapter 1, center C and center c coincide, so the two hemispherical surfaces 11 and 12 overlap and coincide with one another. The existence of a secondary hemispherical surface 13 with center C in the adapter 1 (it has another identical one in the lower part), and a secondary hemispherical surface 14 with center c in the cavity 10 of the tooth 2 (there is another identical one in the upper part of the cavity 10) can also be observed. In rotation of the tooth 2, since the two secondary hemispherical surfaces 13 and 14 (the one of the tooth 2 and the one of the adapter 1 (also referred to as tooth bar)) are concentric spherical surfaces, during the relative movement of one surface with respect to the other surface, the hollow space between both does not increase, so the entry of material is restricted/limited. This has the advantage of the removal forces pressing on the pin 8 being stabilized.