US2384030A - Typewriting machine - Google Patents

Description

Sept. 4, 1945. w. F. HELMOND.

TYPEWRITING MACHINE Filed March 8, 1944 I flit "Vb INVENTOR Wmmm, 9". WM

TTORN'EY- Patented Sept. 4, 1945 TYPEWRITING MACHINE William F. Helmond, CIinton,QConn., as signor to Underwood Corporation, a corporation of Delaware Application March 8, 1944, Serial No. 525,807

- i 2 Claims.

: 'This'; invention relates to type bars for typewriters and like machines, in which the types when actuated start from differentpoints of an arcuate array and move in converging pathsto strike at a common printing point.

In typewriters of this kind clashing or catching of the type heads during the rapid succession of type bar strokes sometimes occurs. This is sometimes due to a particular construction of the composite typ bar, which makes necessary an abrupt shoulder at the back of the type head where same is joined to the type bar proper. During speedy operation of the typewriter, the type face of the next-succeeding type bar, moving. toward the printing point, occasionally clashes with this shoulder of the first-operated type bar as the latter is receding from the printing point, often causing serious damage to the type face.

The main object of the invention is to provide an improved construction by which this clashing or catching of the type head is prevented, to the end that damage to the type face is avoided if the type bars should collide.

More specifically, an object is to provide an improved composite type bar in which the type bar proper affords a transversely converging or laterally tapered form trailing the type head block and resenting a face on each side of the type bar that is substantially a continuation of, and flush with, the type head side.

Another object is to provide a type bar with a tapered portion trailing the type head, of such construction that the tapered portion, although substantially broader than the thickness of the type bar stock, may be formed from the same sheet metal stock, and if desired, may be produced in the same stamping operation in which the type bar itself is produced.

Other objects will be apparent as the following description of a preferred embodiment of the invention proceeds.

In the drawing:

Figure 1 is a fragmentary transverse sectional view illustrating a typical arrangement of the type bars in a typewriter embodying the invention,

Figure 2 is an enlarged detail view of the improved type bar,

Figure 3 i an enlarged sectional view taken on line 3-3 of Figure 2,

Figure 4 is a sectional view taken on line 44 of Figure 2, and,

Figure 5 is a top view illustrating the operation of the invention in preventing catching of the type bars.

The invention is particularly advantageous in front-strike typewriting machines in Whichthe type bars move to the platen in convergent'paths. One example is shown in Figure 1, in which type bars 6 are pivoted on 'an arcuateaxis 1 and are guided by slots in a segment plate 8, to move in paths converging on the printing point. When actuated, the type bar swings toward a platen 9, first striking an anvil IO' and then Whipping into printing engagement with a work sheet on the platen. The full complement of the type bars at rest have the type heads H disposed in an arcuate array and when actuated to print; move in respective paths all convergent at a common printing point defined by a type guide I2. A lip l3 on each type bar-cooperates with the type guide l2 in the usual manner to bring the type head exactly to the printing point.

In Underwood typewriters the type head ll and the arm 14 composing the complete type bar, are separate pieces, as shown more clearly in Figure 4. The arm I4 is produced by stamping, from relatively thin sheet-metal stock, usually by a single stamping operation. The type head ll requires a substantial thickness, several times that of the type arm M, to afford an adequate area for the type and a hammer effect in printing. To securely mount the type head, same has a slot l5 of appreciable depth and of a width to receive the type arm, on which the type head is firmly secured, preferably by soldering the adjacent surfaces within the slot l5.

It will be observed that this construction and assembly of the composite type bar results in having an abrupt shoulder I6 along the trailing edge of the type head. The members of the type head on each side of the slot l5 necessarily have a substantial thickness throughout to assure ruggedness and, although some tapering toward the back edge is permissible as shown, the eliminationof the shoulder l6 by tapering, say to a feather edge, is impractical. In typewriters heretofore in use, having type bars constructed similar to the above, damage to type faces, such as deforming the serifs, has resulted from the nextactuated type head striking the shoulder I6 of the preceding type head before the latter could recede sufficiently from the platen.

It is well known to guard against damage to the type faces resulting from edge-to-edge collision of the type bars by providing a prong projecting rearwardly from the type head. This feature, per se, is included in the embodiment shown, to complete the illustration of the type bar structure. The type bar is extended at IT,

back of shoulder l6, to-form a projecting rounded thickest type head will be suitable for all.

point or prong l8 reaching somewhat back of l the adjacent longitudinal edge of the arm, with the edges of the extensions diverging from said point. Should one type head collide with the back edge of another, damage to a type face is avoided by the rearward prong l8 of. the leading type bar engaging the colliding bar at an area between the upper and lower-case type faces;

As afore indicated, the present improvements, now to be described, are directed to avoiding damage to the type face resulting from collision cording to the invention, the portion ll trailing the type head is enlarged or expanded laterally so that the outermost surfaces of the arm at this portion are substantially flush with the side faces of the type head. To provide this enlargement,

the extension ll is extruded at 20 and 2| in op-- posite lateral directions to form a, rib or boss at each side of the type bar. Each boss 20, 2| begins just back of the type head shoulder l6 where its outer face is substantially flush with, and, :forms a continuation of, the type head side.

Each boss may project slightly beyond the type head, as shown, so as to be adequate for type heads of abnormal thickness. If the type heads ofall the characters vary materially, as is usual in some typewriters, bosses adequate for the In this way uniform type arms, insofar as otherj wise'practicable, may be used. From its end ad- .sideways, particularly at the shoulder "16. -Accollisions, as shown in Figure 5, the bosses 20, 2| avoid this damage. As the two type bars come together, the boss deflects the type head of the rearmost type bar so that its type-face will not strike or catch on the shoulder IE, but will continue past the type bar, after only a light glancing impact at the sides. The taper of the bosses, as wellas otthe. type head, is so, gradual that only a, light impact results as the two type bars engage each other. 7

What is claimed is:

1. In a type bar assembly for front-strike typewriters, having a relatively wide type head with rearwardly extending side members affording a slot therebetween, and a relatively thin, sheetmetal type-carrying arm secured in the slot of the type head and having a portion substantially trailing the type head; the'improvement of. providing at least one boss on each side of the trailing portion of the type arm, each boss extending rearwardly from a point just back of the type head side member, atwhich point the boss is substantially flush with said member, and each boss being tapered rearwardly to grade into the thin body of the arm at its trailing extremity.

2. In a type bar assembly for front-strike typewriters, having a relatively wide type head with rearwardly extending side members afiording a slot therebetween, and a relatively thin, sheetmetal'typecarrying arm secured in the slot of the type" head andhaving a portion substantially trailing thetype head; the improvement of providing two oppositely directed extrusions in adjacent areas of the'trailing portion of the type arm; each extrusion forming a ridge starting just rearward of type head side member and substantially flush with said member, each ridge being inclined longitudinally'to blend into the thin sheet forming the trailing extremity of the type nnc WILLIAM l5". HELMOND.

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