Excavating tooth, replacement tooth point and method for installing the tooth point

Abstract: A tooth point (10') having key slots top and bottom wherein the rear walls of the slots (16',17') are outwardly convergent relative to the front walls to permit receipt of a curved locking pin (15').

Description: This invention relates to a method of installing a mining tooth point and, more particularly, to a point that is more easily installed on, but is more difficult to remove from the supporting adapter. Notwithstanding subsequent tooth developments in the form of US-A-4,231,173 (the SUPER CONICAL®) and US-A-4,335,532 (the HELILOK®), the tooth that has remained the standard for mining is the No. 77 CONICAL®. This tooth is a combination of US-A-2,919,506 and US-A-3,079,710 and employs a pin lock of the type seen in US-A-3,126,654 which is the document on which the precharacterizing part of claims 1 and 3 is based. The designation 77 relates to the fact that the horizontal dimension of the tooth point socket measures 0.2 metres (7.7 inches) at the conical axis adjacent the rear of the point. The principal problem with these points is the difficulty of installing the locking pin. The problem is not so severe in some instances with the smaller teeth and, the larger teeth employ a spool and wedge. The point and adapter nose have aligned vertically extending openings into which a "corrugated" pin is installed --to cooperate with a complementary rubber lock or keeper. A frequent experience has been that the strongest man in the shift equipped with a heavy sledge has extreme difficulty in driving the locking pin to final assembly. It should be appreciated that these teeth parts are quite heavy, the point weighing upwards of 45 Kg (100 pounds) and the adapter upwards of 181 Kg to 227 Kg (400 to 500 pounds). Replacement is often performed under arduous conditions in the field. It also will be appreciated that the points wear rapidly and require replacement. Depending upon the abrasiveness of the material being excavated, a point may last from a matter of hours to a matter of days or weeks. In any event, there is relatively frequent replacement -- at least in terms of the adapter life. Normally an adapter will last from about 5 to about 30 replacement points. The problem of installation has been solved by the instant invention through the use of a pair of novel shaped pin-receiving openings in the point which accommodate the receipt of a complementarily shaped locking pin. More particularly, the rear generally vertical walls of the point pin openings have been changed from being co-planar to now being each outwardly convergent each with its associated pin opening front wall. For definitions of the invention, attention is drawn to the appended claims. In an embodiment described below the forward surface of the pin has three, non-coplanar projects. The use of outwardly converging walls and a pin with a corresponding inclination making possible (a) more offset between the inner ends of the point opening rear walls and the nose opening rear wall than the offset characteristic of the same tooth according to the prior art having vertical rear walls in the point openings, thereby providing more takeup of the point on the adapter nose; (b) less interference in installation, and (c) increased bearing area between the pin and point opening rear walls. Pertinent art are US-A-4,182,058 and US-A-4,455,771 which show an inclined rear wall in one of the point pin opening but for a different purpose. Other objects and advantages of the invention will be seen in the details of the ensuing specification. The invention is described in conjunction with the accompanying drawings, in which -- FIG. 1 is a perspective view, partially broken away of a tooth equipped with the point and pin, according to the invention; FIG. 2 is an exploded fragmentary side elevational view, partially in section of the prior art 77 tooth; FIG. 3 is a view essentially similar to that of FIG. 2 but featuring the inventive point and complementarily shaped pin; FIG. 4 is another view of the prior art tooth showing the pin partially assembled in the aligned openings in the point and adapter nose; FIG. 5 is a view corresponding to that of FIG. 4 but with the inventive point, and pin being illustrated; FIG. 6 is again a fragmentary, side elevational view partially in section of a pin adapter nose and point in assembled condition as would be characteristic of the prior art; and FIG. 7 is a view of the inventive construction corresponding to the showing in FIG. 6. In the illustration given and with reference to FIG. 1, the numeral 10′ designates generally the inventive point which is seen to be mounted on the nose generally designated 11 of the adapter 12. The adapter 12 is seen to be equipped with a wear cap 13 which is optional. Completing the assembly of the mining tooth are a plug 14 and a pin 15′. The prior art elements lack the prime (′). The interrelationship of the parts of the mining tooth can be readily appreciated from the exploded view seen in FIG. 2. There, again, the point is generally designated by the numeral 10 and is seen to have vertically aligned openings 16 and 17. The nose 11 is seen to have a vertically extending opening 18 which is generally alignable with the openings 16 and 17. The plug or keeper 14 is seen to be equipped with four projections 19 developed by cylindrical inserts in the fashion shown and described in US-A-3,126,654. The pin 15 (shown spaced above the point-nose combination) has five projections or "bumps" as at 20 and these are all in a line, i.e., the tips are coplanar. The rear of the pin at 21 is completely flat. Referring to the lower portion of FIG. 2, there is an offset 22 between the back 23 of the key slot or opening 18 in the nose and the back 24 of the pin opening 16 in the point. This offset allows takeup for the point on the nose as the nose surface wears down. The larger this offset, the more takeup is available for a point-nose assembly. Referring to the upper part of FIG. 2, there is a large bevel at 26 and 29 at each end of the pin 15 to facilitate installing the pin past the offset 22 in the point-nose assembly. In FIG. 3 like numerals are employed for elements identical to those just described in FIG. 2. Where the element is different, a prime (′) is added. Thus, the nose is designated by the numeral 11 because it remains unchanged. However, the point is designated generally by the numeral 10′ to indicate that there is a change between the two showings. The difference in the points resides in the provision of a forward bevel or inclination 24′ on the back edge of each of the pin openings 16′ and 17′ in the point. This provides a substantially greater amount of offset 22′ between the bottom (not the top) of the rear wall 24′ of the key slot 16′. This increased amount of offset 22′ allows for more takeup of the point on the nose in cooperation with the increased bevel 26′ on the back of the pin 15′. This increased bevel can be appreciated by comparing the top portions of FIGS. 2 and 3 and in particular the bevels at 26 in FIG. 2 and 26′ in FIG. 3. Still referring to the upper portion of FIG. 3, there is provided an offset 27′ between the center bump 20 and each of the two adjacent bumps 20′. Please note that there are only three bumps on the front of the pin 15′ rather than the five that are on the prior art pin 15. Another significant feature of the new pin 15′ is that it has the ends of the pin beveled with only a small radius at the very end of the pin rather than the large chamfers that are characteristic of the prior art pin 15. The two views of figures 4 and 5 show the pin partially installed within the pin openings of the assembled point-nose combination. In both cases, the pins are driven in from the top. It is to be noted that at the location 28 at the bottom of the assembly, the offset between the pin opening or key slot in the nose and the key slot in the point is causing difficulty for the pin to slide by this location. That is the reason for the large bevel or radius at the extreme lower end of the back of the pin as at 29 -- see the upper portion of FIG. 2. Also, it will be appreciated that at the same time the pin 15 hits the obstacle at the location 28 during assembly, the first bump on the front of the pin as at 20a in FIG. 4 also contacts the last steel cylinder 19a in the rubber lock 14. As the pin 15 goes past the point 28 (or the offset between the point and nose), it is forced forward and down on the cylindrical insert 19a. This makes it extremely difficult to drive the pin into this assembly because the last steel cylinder is driven against the inside surface of the point at the location 14a. It has been experienced that on difficult assemblies that after the installation of the pin, one can remove the pin and find this cylinder broken and the rubber lock destroyed. FIG. 5 shows the pin 15′ driven into a new point and nose assembly. This is at the same stage of installation as that shown in FIG. 4. It is to be noted that in FIG. 5 there is no significant interference at the point 28′. This is the contact area at the bottom of the inside of the point at assembly because of the fact that a large bevel is provided at the back of the pin as at 26′ and 29′. It is also to be noted that instead of trying to compress the last cylinder in the lock 14 at the same time the pin 15′ is trying to jump past the area 28′, there is a clearance instead between the pin 15′ and the bottom cylinder 20a′. FIG. 6 shows a fully engaged pin in the assembly of point 10 and nose 11. It is to be noted that there is a dimension 30 at the bottom showing the effect of the large bevel on the back of the pin 15 has with respect to the surface contact between the pin 15 and the rear wall 24 of the key slot 17. It also will be appreciated that there is a very slight amount of take up or clearance between the back of the nose slot and the back of the pin as at 31. On the other hand, FIG. 7 shows a fully installed pin with the new point 10′, a standard nose 11 and a standard plug or lock 14. It is important to note the difference between the compression on the rubber lock 14 at the center thereof as shown by the dimension 32. This increased compression holds the point 10′ tighter on the nose 11 and increases the stability of the entire system. Also, please note the amount of clearance between the back of the pin and the back of the key slot in the nose as at 31′. This increased clearance allows for more takeup which is provided by the increased compression on the rubber lock. Another significant thing about this system is that there is virtually 100% contact between the back of the pin 15′ and the mating surface of the point. The slight departure from this is designated by the numeral 30′ applied to the dimension at the lower right hand portion of FIG. 7. Increased stability is afforded because for the pin 15′ to move out of the FIG. 7 position, it now has to climb up out of a valley formed by the two interfaces between the bevels on the back edge of the point pin openings. It is also cradled in a curved portion of the lock which surrounds the three bumps at the front of the pin. The particularly advantageous features of the invention are: 1. Much easier installation of the pin into the assembly because of the bevels at the back end of the pin providing ramp surfaces of the order of about 15° and eliminating the interference present on the prior art system; 2. Elimination of the bottom outside bumps on the pin, eliminating the interference between that bump and the bottom cylinder at installation; 3. Increased allowable offset between the back of the pin opening in the nose and the back of the pin openings in the point allowing for more takeup of the point on the nose; and 4. Curvature on the front of the pin 15' formed by the bumps not being in a straight line and therefore forcing the rubber lock to wrap around this pin when it is fully installed. It has been noted that the inventive system is easier to install, even in very cold weather, does not damage the rubber lock at installation (as did the previous system) and is more stable after installation. The inventive system also requires more energy to disassemble because of the ramps on the two surfaces and the curvature at the front of the pin which is beneficial to pin retention during operation.

Claims: An excavating tooth comprising a point (10') having a generally wedge-shaped body including a front digging edge and a rear end defining a forwardly extending opening, said opening being bounded by a pair of opposing walls each defining a transverse hole (16', 17') extending through the wall, said holes (16', 17') each having a rear face (24') and a front face (33); an adapter (12) having a body defining a forwardly projecting nose (11) and a passage (18) extending completely therethrough, said passage (18) having a front face and a rear face, said front face being defined by a resilient insert (14) defining a series of spaced apart bumps (19), said nose (11) of the adapter (12) being received in said opening in the rear of the point (10') such that said passage (18) is generally aligned with said holes (16', 17') in the point walls; and a lock pin (15') having a pair of ends and being received into said holes (16', 17') in said point (10') and said passage (18) in said adapter (12) to secure the point (10') onto said adapter (12); characterized in that each said rear face (24') of said point (10') is inclined to converge toward its respective front face (33) in an outward direction; said lock pin (15') has a front wall defining a series of bumps (20') arranged in a generally convex manner, said bumps (20') being less in number than said bumps (19) provided on said adapter insert (14); and said lock pin (15') has a rear wall having a pair of inclined end segments (26', 29') oriented to converge relative to one another in the rearward direction, each said end segment (26', 29') being positioned in flush engagement with a respective one of said rear faces (24') of the holes (16', 17') of said point (10') and with said bumps (20') of said lock pin (15') located between said bumps (19) of said adapter insert (14) when said lock pin (15') secures said point (10') onto said adapter (12). A method of installing the tooth point (10') as defined in claim 1 on the adapter (12) as defined in claim 1 to form the excavating tooth as defined in claim 1; consisting of the steps of i. inserting one end of the lock pin (15') as defined in claim 1 into one of the holes (16', 17') in the tooth point (10') such that one of the inclined rear segments (26', 29') lies opposed to the rear face (24') of one of the holes (16', 17') ii. driving the lock pin (15') through said one hole (16', 17') in the tooth point (10') and into the passage (18) of the adapter (12) until said inclined rear segments (26', 29') lie adjacent and substantially parallel to the rear face (24') of the respective hole (16', 17') in said point (10'), iii. continuing to drive said lock pin (15') so that the inclined rear segments (26', 29') are abutted generally flush against the rear faces (24') of the hole (16', 17') of the tooth point (10') before the bumps (20') of the lock pin (15') have engaged all of the bumps (19) of the adapter insert (14) and iv. continuing to drive said lock pin (15') after the abutment of the inclined rear segments (26', 29') with the rear faces (24') of the tooth point (10') holes (16', 17') until the bumps (20') on said lock pin (15') are received between said bumps (19) on the adapter insert (14). A replacement point (10') for an excavating tooth according to claim 1 having a generally wedge-shaped body including a front digging edge and a rear end defining a forwardly extending opening, said opening being bounded by a pair of opposing walls each defining a transverse hole (16', 17') extending through the wall, said holes (16', 17') each having a rear face (24') and a front face (33); characterized in that each said rear face (24') of said holes (16', 17') is inclined to converge toward its respective front face (33) in an outward direction. A replacement point (10') according to claim 3 wherein the rear face (24') is inclined at an angle of 15°.

Inventors: BRISCOE TERRY L, JONES HERBERT E, KREITZBERG JOHN S, BRISCOE, TERRY L., JONES, HERBERT E., KREITZBERG, JOHN S.
Applicants: ESCO CORP, ESCO CORPORATION
Application year: 1989
Main classification: E02F9
IPC codes: E02F9