Wear resistant cutting edge and method for making same

An elongated steel cutting edge has an insert receiving slot formed therein extending from one end to the other. A plurality of carbide inserts of a generally rectangular solid configuration have a front face, a rear face and four sides. A plurality of upstanding protuberances are formed on and extend beyond the rear face of the inserts. The inserts are located within the slot in closely spaced side by side relationship and with the protuberances located against one of the sides of said slot. The front and rear faces of the cutting edge are brought together along the slot to cause a mechanical interlock between the protuberances of the insert and the cutting edge.

TECHNICAL FIELD 
The present invention generally relates to a cutting edge .for snowplow 
blades and, more particularly, to a wear resistant cutting edge with 
carbide inserts. 
BACKGROUND ART 
Snowplow blades and the like are constructed with replaceable cutting edges 
so as to enable the removal and replacement of such cutting edge after it 
wears out. Such cutting edges are typically made of hardened steel. 
However, due to their running engagement against concrete and asphalt road 
surfaces, cutting edges are still subject to high rates of abrasive wear 
and need frequent replacement. Placing carbide on the leading edge of such 
cutting edges would greatly extend the wear life of the cutting edge. 
However, attempts to use carbide on cutting edges has only met with 
limited success. One reason is that carbide is extremely brittle and 
subject to fracture when subjected to high impact loads. If all or major 
portions of the carbide is lost due to breakage, its wear protecting 
ability is also lost and the extended life potential of cutting edge that 
should result from the carbide is not realized. Carbide is a high cost 
material. Not realizing its full life potential because of this loss 
results in undue economic waste. Another reason for its limited use is 
that carbide is difficult to attach to the steel cutting edge, such 
attachment typically being accomplished by an expensive brazing operation. 
The present invention is directed to overcoming one or more of the 
preceding problems.

BRIEF DESCRIPTION OF THE DRAWINGS 
FIG. 1 is fragmentary side elevational view a wear resistant cutting edge 
embodying the principles of the present invention. 
FIG. 2 is a rear view of the cutting edge taken along line 2--2 of FIG. 1, 
with a portion broken away to show the carbide inserts of the present 
invention. 
FIG. 3 an enlarged prospective view of one of the carbide inserts depicted 
in FIGS. 1 and 2 and illustrating one distribution pattern for the 
protuberances contained thereon. 
FIG. 3a is a view similar to FIG. 3, but illustrating another protuberance 
pattern. 
FIG. 4 is a cross-sectional view of one of the carbide inserts taken along 
line 4--4 of FIG. 3. 
FIG. 5 is an enlarged cross-sectional view of the cutting edge taken 
generally along line 5--5 of FIG. 2. 
BEST MODE FOR CARRYING OUT THE INVENTION 
Referring more particularly to the drawings, a replaceable, wear resistant 
cutting edge embodying the principles of the present invention is depicted 
at 10 in FIGS. 1 and 2 for use on a snowplow blade or the like (not 
shown). Snowplow blades are mounted on trucks or other vehicles (also not 
shown) and are used for removing snow and ice from roads, parking lots, 
airport runways and the like. Because road surfaces and the like are 
typically constructed from concrete or asphalt, snowplow blade cutting 
edges are subject to extremely high amounts of abrasive wear and must be 
frequently replaced with new cutting edges. 
The wear resistant cutting edge 10 of the present invention is constructed 
to afford greater wear life by reducing such abrasive wear. 
To this end, the cutting edge 10 includes an elongated steel cutting edge 
plate 12 having a front face 14, a rear face 16, a pair of opposite ends 
18,20 and a leading edge 22. The plate also includes top edge 24, along 
which a plurality of plow bolt holes 26 may be provided for detachably 
securing the cutting edge plate 12 to the moldboard (not shown) of the 
snowplow blade. As such moldboards are typically curved, the edge plate 12 
is preferably provided with a mating curved configuration, as shown in 
FIG. 1. However, plate 12 could be made straight as well. 
The leading edge 22 has an insert receiving slot 28 formed therein. Slot 28 
extends from one of the ends 18 to the other end 20. Slot 28 has a front 
side 30 and an opposing rear side 32 and is generally centrally located 
between and with the front and rear sides 30,32 being generally parallel 
to the front and rear faces 14,16, respectively, of the cutting edge plate 
12. 
The present cutting edge further includes a plurality of carbide inserts 34 
of a generally rectangular solid configuration, with a front face 36, a 
rear face 38 and four sides 40,42,44,46, and a plurality of upstanding 
protuberances 48 formed on and extending beyond the rear face 38 of the 
inserts 34. The inserts 34 are located within the slot 28 in closely 
spaced side by side relationship and with their protuberances being 
located against and along the rear side 32 of the slot 28. A closely 
spaced relationship, rather than a tight abutting relationship, is 
necessary in order to accommodate the difference in thermal expansion 
between the steel cutting edge plate 12 and the carbide insert 34 when 
they become heated, which occurs during manufacture, as will hereinafter 
be more fully described, and/or during use of the cutting edge 10. 
The inserts 34 may be made of a cemented carbide compound of tungsten 
carbide and 11 cobalt binder. However, the present invention is not 
intended to be limited to any particular compound as many any well known 
carbide compositions will function in the disclosed application, as those 
skilled in the art will appreciate. 
The inserts 34 have a thickness between the front and rear faces 36,38 of 
about 3 to 60 mm and preferably a thickness of about 6 mm. The inserts may 
have a width between sides 42,46 of between about 10 to 50 mm and a length 
between sides 40,44 of between about 10 to 150 mm. An insert with a width 
of about 25 mm and a length of about 25 mm has been used with satisfactory 
results. The protuberances 48 have a pyramidal-shaped configuration as 
best seen in FIGS. 3 and 4 and extend beyond the rear face 38 of the 
inserts 34 by about 5 to 20% of the thickness of the insert. For instance, 
a height of about 1 mm for the protuberances may be used for an insert 
that is about 6 mm thick. 
As shown in FIG. 3, the protuberances are preferably arranged in columns 
and rows in a checkerboard like fashion. Alternately, an insert 34 may 
have the protuberances 48' that are arranged in diagonally oriented 
columns and rows, as shown in FIG. 3a. 
As best shown in FIG. 5, the leading edge 22 of the cutting edge 10 is 
beveled with a first beveled surface 50 and a second beveled surface 52. 
The leading side 46 of the insert 34 is provided with a mating bevel 
surface 54 thereon that matches the first beveled surface 50, which, 
together, provide a sharp point that enhances to scraping ability of the 
cutting edge 10. 
INDUSTRIAL APPLICABILITY 
In accordance with the present invention, the cutting edge 10 is 
constructed in a manner to keep the carbide inserts 34 within the slot 28 
during use by bringing the front and rear faces 14,16 of the cutting edge 
10 together along the slot 28 to cause a mechanical interlock between the 
protuberances 48 of the insert 34 and the cutting edge 10. To accomplish 
this, the carbide inserts 34 are placed in generally closely spaced, side 
by side relationship within the slot 28 of the cutting edge 10 and with 
the rear face 38 with the protuberances 48 facing the rear face 16 of the 
cutting edge plate 12. The inserts 34 are preferably spaced a sufficient 
distance apart from each other to accommodate the difference in thermal 
expansion rates between the inserts and the steel cutting edge plate 12, 
thereby relieving stresses in the inserts 34 and possible breakage during 
use or during construction as described below. 
The leading edge 20 of the cutting edge 10 is then heated to a temperature 
of between about 1500 degrees to about 1800 degrees Fahrenheit. While in a 
heated state, a press force by means of a hydraulic press or the like (not 
shown) is then applied against the front and rear faces 14,16 of the 
cutting edge 10 along the leading edge 22 sufficient to cause plastic 
deformation of the cutting edge plate 12 around the protuberances 48. This 
creates a mechanical interlock between the cutting edge 10 and the 
protuberances 48 of the inserts 34. 
Because of metal flow around the protuberances 48, the insert 34 can not 
become dislodged from the slot 28 during use. The pyramidal shape of the 
protuberances 48 resists movement in both longitudinal and lateral 
directions. The use of many and the placement of the protuberances 48 in a 
checker board-like pattern reduces the amount of carbide loss in the event 
of breakage or cracking of the insert due to impact during use. This is 
because each protuberance 48 will retain any piece of carbide in which 
such protuberance resides, so that any cracking that occurs does not 
result in the loss large portions of the insert that might otherwise 
occur. 
Other aspects, objects and advantages of this invention can be obtained for 
a study of the drawings, the disclosure and the appended claims.