US2643438A - Method of making plow bottom parts, particularly moldboards - Google Patents

Description

June 30, 1953 w. E. RUSKA 2,643,438

METHOD OF MAKING PLOW BOTTOM PARTS, PARTICULARLY MOLDBOARDS Filed Jan. 12, 1951 FIGi INVENTOR- WiniamE. Ruska/ A TTORNEY Patented June 30, 1953 UNITED STATES TENT OFFICE METHOD OF MAKING PLOW BQTTOM PARTS, PARTICULARLY MOLDBOARDS Application January 12, 1951, Serial No. 205,768

3 Claims.

This invention relates to a method of making plow bottom parts, particularly moldboards, and has for an object the provision of improvements in this art.

One of the particular objects of the invention is to provide a method of making plow bottom parts, particularly moldboards, with a hard jacket and a soft tough core which requires the minimum of surface finishing operations after hardening, whereby to leave a hard jacket or shell of uniform depth over the entire surface area of the part.

Another object is to provide a method of making plow parts wherein, of the total of operations required, the maximum number of operations are performed on flat stock and the minimum number of operations on the final curved stock.

Another object is to provide a method of making plow bottom parts which promotes improved and more uniform annealing of the stock.

Another object is to provide a method in which the heat-treating heat is used for subsequent forming and hardening operations.

Another object is to provide a method of making plow bottom parts which gives greater econonly and facility of handling in the process as a whole.

The above and other objects and advantages of the invention will be apparent from the following description of an iilustrative embodiment thereof, reference being made to the accompanying drawings, wherein:

Fig. l is a perspective view of a rolled strip from which the parts are to be cut;

Fig. 2 shows a stack of flat strips during annealing after hot rolling;

Fig. 3 is a plan view showing how blanks are cut from the strip, holes being punched in the same operation;

Fig. 4 shows the surface finishing operation on the fiat stock;

Fig. 5 shows the chemical heat-treating operation, as in a carburizing furnace;

Fig. 6 illustrates a die shaping operation;

Fig. 7 illustrates a quenching operation; and

Fig. 8 shows the final plow bottom assembly.

The specific plow bottom part which is taken for illustration in connection with the present method is a moldboard is having bolt holes H with squared countersunk portions for bolts for securing the part to a plow bottom saddle or frog. The moldboard has a lower joint edge I? adapted to fit a share It (Fig. 8).

It is desired that the finished moldboard will have a hard wear-resisting jacket or shell and a soft tough core. If a hard jacketed strip is taken at the start all of the forming operations are made diflicult and expensive; whereas if a soft blank is used, such as soft high-tensile steel, it may have many of the shaping operations performed before the hard jacket is formed. Besides, the soft material is much less expensive than the hard clad (soft center steel) material.

The original stock from which the parts are made consists of a flat hot-rolled strip I5 (Fig. 1) which readily stacks and holds its heat for annealing, as shown in Fig. 2.

After annealing, the strip is cut to form blanks (Fig. 3) and in the same operation the bolt holes H may be formed. In a succeeding operation the square countersunk portions of the holes are formed.

Next, and while the stock is still fiat and soft, the surfaces are ground or polished, or both, to provide the final thickness dimensions, as shown in Fig. 4. Plow shapes are quite complex and it is a slow and expensive job to grind them in their final shape, and this is especially true when the surface has been hardened. In the flat soft state the main grinding can be done for a small part of what the cost of finish grinding would be. While a slight final grinding or polishing may be necessary it is not nearly so expensive as it would be if all grinding had to be performed in the final state. By grinding in the flat it is possible to use wide-faced cylindrical grinding rolls or even to grind by automatic machines. Final grinding of contoured shapes must be done by hand, as by cradles with small grinding rolls and requires highly skilled labor, hence is very expensive.

The ground blanks are placed edgewise and spaced apart in a tray I9 (Fig. 5) and heated in a suitable chemical atmosphere to give them a hard or hardenable outer jacket completely surrounding a soft tough core. In the present case the blanks are given a carburizing treatment, as in a carburizing furnace 20, a number of blanks being carried by each tray.

Subsequent to the carburizing treatment the blanks are taken out one by one and, with the same heat, are forged in a die press 22 to take their final shape.

While still hot from the press the blanks, when at the proper temperature, are quenched in a bath 24, as of a suitable salt solution (Fig. 7) to form a hard jacket. The hardened parts may be reheated and annealed if necessary.

Finally the shaped and hardened moldboard is secured, along with other parts, on a plow saddle (Fig. 8). If necessary the assembled parts may be given a final grinding operation to make the joint and bolt head zones smooth and even. The smooth surface may then be oiled and polished to a micro-finish, if desired.

It may now be seen that the method is very efiicient and economical. By grinding the parts while fiat and unhardened and by shaping the parts while hot and unhardened, great overall economy of operation is attained. Moreover, the hard jacket does not have to be ground to any extent in the final form, thus avoiding the expense of such final grinding operations and leaving a jacket of uniform thickness on the part.

While one embodiment of the invention has been described for purposes of illustration, it is to be understood that there may be various modifications within the general scope of the invention.

What is claimed is:

1. The method of making plow bottom parts of curved shape with bolt holes and having a hard jacket and a soft core, which comprises, grinding and cutting out blanks from fiat rolled stock, chemically heat treating the separate blanks to condition them for the formation by quenching of a hard jacket, shaping the blanks while soft to final shape, quenching the shaped 3G blanks from a heated condition, assembling the parts with others on a plow bottom, and light 4 grinding and polishing the composite plow surface.

2. The method of making plow bottom parts of curved shape with bolt holes and having a hard jacket and a soft core, which comprises, hot-rolling and stack-annealing the stock in the fiat soft strip form, grinding and cutting out blanks in flat soft form, bolt holes being formed in the blank cutting operation, chemically heattreating the blanks to give them a penetrating hardenable jacket, die-forging the hot blanks to final shape, quenching the shaped blanks, assembling the parts with others on a plow bottom, and giving the composite surface a light finish grinding and polishing operation.

3. The method of making a curved plow moldboard having a hard jacket with a soft core and with hard-surfaced bolt holes, which comprises, cutting and grinding blanks in the flat, heat treating the blanks in a penetrating atmosphere to provide a hardenable jacket, die forging the still hot blanks to final shape, quenching the blanks, and finally giving the parts a light surface finishing operation.

WILLIAM E. RUSKA.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 356,530 French Jan. 25, 1887 1,603,199 Erickson Oct. 12, 1926

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