US1652810A - Weighing machine - Google Patents

Description

Dec. 13; 1927.

A. BOUSFIELD WEIGHING MACHINE -Filed Nov. 1 s; 1925 Fig.1.

15 F1H.E. 21 13 16 L 12 1 Fig.5. I

INVENTOR Alfred Bog f'lkrld,

ATTORNEY Patented Dec. 13, 1927.

UNITED STATES PATENT OFFICE.

ALFRED BOUSF IELD, OF ST. JOHNSBURY, VER-MONT,ASSIGNOR T0 E. AND T. FAIR- BANKS AND COMPANY, OF ST. J OHNSBURY, VERMONT, A CORPORATION OF Z,VER-

IVIONT.

WEIGHING MACHINE.

Application filed November 13, 1925.

My present invention relates to weighing machines, and has for its object to provide an improved knife edge pivot therefor.

In order that a scale may weigh properly, the pivots in scale levers and beams must be placed with great exactness and the practice of casting the levers with the pivots in place results in the loss of many castings owing to the pivots having been improperly placed or having shifted in the mould. Furthermore, the pivots lose their temper and often warp during the casting process and must be re-shaped and re-hardened, which involves grinding and heating operations that, when the pivots are fixed in the lever, are diflicult to carry out, especially if the lever be a heavy one. lVhere a pivot is thus fixed in place it must be formed of a bar of sufficient cross-section to support the weight, and as these bars are of high-grade steel, their cost is considerable. The practice of inserting the pivots in holes drilled in the lever is also followed to some extent, but such inserted pivots must be formed of even heavier bars than are used to form pivots which are fixed in place in casting and the cost of such inserted pivots is therefore also very great. In some types of scales it has been the custom to form the pivots with a cylindrical portion that is mounted in holes drilled in the lever or other scale part, and projecting longitudinally from such cylindrical portion are the knife edges. The cylindrical portion of the pivots of this character have greater area than the knife edge portion, however, in. manufacturing this type of pivot, considerable difiiculty has been experienced in machining the parts whereby the knife edges will be properly alined.

Generally stated, a pivot falling within the scope of my invention is composed of two pieces, one of which is cylindrical in form and provided with a rectangular groove, the bottom of which groove lies along the longitudinal axis of the cylinder, and the other piece is substantially rectangu lar in form for engaging with the sides of the groove, and has a knife edge portion resting on the bottom of the groove, the second piece being frictionally retained by the first piece, and the first piece being frictionally line 33 of Fig. 2;

Serial No. 68,760.

mounted in a hole drilled in the lever or other scale part, both pieces being fixed in position without using auxiliary fastenings.

The invention is illustrated in the accompanyingdrawings in which Figure 1 is an elevation of a weighing machine, showing the application of my invention thereto;

Fig. 2, is a horizontal section taken approximately on the line 22 of Fig. 1, most of the parts being shown in plan;

Fig. 3, is a transverse section taken on the 4 is a detail view of the pivot, and

Fig. 5 is a transverse section taken on the line 5-5 of Fig. 4.

My invention can be used in the various plvotal connections of weighing or other like machines, therefore, I have chosen to show in the present embodiment the same applied to the scale shown in United States Letters Patent #1,346,481 issued July 13, 1920.

Referring now to the drawings, the arm 12 is pivotally mounted by means of a pivot 13 seated on bearings 14 carried in the top of a support 15. The forward segmental end 16 of the arm has attached thereto a tape 17, while an eccentric 18 to which is attached a tape 19 is. mounted so as to extend rearwardly of the pivot 13. Both of the tapes are connected to other parts of the scale mechanism and function in the manner fully described in the patent, the arm swinging on its pivot during the operation of the scale in the usual well known manner.

For the purpose of facilitating construc tion of scale parts it has been the custom to form the arm from a casting. One end of the arm is bifurcated to provide a pair of spaced hubs 20 in which are drilled alined openings 21 for receiving the pivot. The eccentric 18 is carried by the pivot in the space between the hubs 20 (see Figs. 2 and 3.)

As shown, the pivot comprises a cylindrical body from which projects alined knife edges that are disposed coincident with the longitudinal axis of the main body of the pivot. Heretofore pivots of this character have been formed in various ways. Some have been cut from a solid piece of material, while others have been composed of assembled parts suitably fastened together. In all cases, however, accurate machining of the parts is required so as to obtain articles suitable for use in sensitive weighing machines.

In order to produce a pivot wherein the oppositely projecting knife edges would be in perfect alinement, considerable machining and grinding has been required, which work has unreasonably increased the costof the articles. Furthermore, it has also been dill.- cult for the workmen to determine with accuracy whether or not the two knife edges were properly alined. Therefore, in order to obtain a better article which could be readily manufactured at little expense, the pivot 13 is composed of two pieces, a cylindrical body, which is madefroin a suitable length of round barsteel, and knife edge portion 22, which is made from a suitable length of rectanguiar'bar steel. i

In producing the pivot, the cylindrical body portion has a rectangular channel or groove23 formed the length thereof, such groove having parallel sides and a flat bottom 24, which latter is disposed coincident with the longitudinal'axis of the body. The

knife edge bar 22, which has a wedge-shaped portion '25 tapering from parallel sides 26, is adapted to be driven or pressed into the groove 23 with the lower edge ofthe portion 25 seated along the bottom 24. In forming the pivot, it is the practice to. form the groove 23 of a width corresponding tothe thickness of the knife edge bar 22. The

sharpened edge portion of the bar is carefully ground before the partsare assembled. Should the upper edge of the bar project above the surface of the cylindrical body, after the bar has been properly seated in the groove, the exterior surface of the pivotcan be ground down to the desired diameter that will enable the pivot to be driven into proper position in the openings 21 of the arm 12. 'ihisconstruction has enabled an accurate article to be produced without resorting to the use of screws, bolts or other auxiliary fastenings for securing the parts together.

Having thus described my invention, what I claim is Y 1. A scale pivot comprising a cylindrical body portion having a substantially rectanguiar groove extending longitudinally thereof and a knife-edged bar having parallei side faces'for frictionaiiyengaging the side walls of said groove, said knife edge resting on the bottom wall of said groove and being spaced from the side wall thereof 2. A scale'pivot comprising a cylindrical body portion having a substantially rectangular groove extending longitudinally thereof and a knife-edged bar having parallel side faces for frictionaily engaging the side walls of said groove, said knife edge resting on the bottom wall of said groove.

In testimony whereof I hereunto sign my name. I t V ALFRED BOUSFIELD.

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