US2625100A - Printing hammer rebound preventing means - Google Patents

Description

Jan. 13,1953, M. WILLIAMS ETAL I 2,625,100

PRINTING HAMMER REBOUND PREVENTING MEANS Filed Jul 24, 1947' Envntors HARRY M WILLIAMS AND JAMES E. J HNSON By W Their (Ittorneg i 'atented Jan. 13, 1953 2,625,100 7 PRINTING HAMIWER REBOUND PREVENTING MEANS Harry M. Williams, Oakwood, and James E. Johnson, Dayton, Ohio, assignors to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Application my 24, 1947, Serial No. 763,352

11 Claims. (Cl. 101-93) This invention relates to improvements in means to prevent rebound of spring-actuated printing hammers used in cash registers and calculating machines.

The principal object of the invention is to provide means to prevent spring-actuated printing hammers from rebounding after making a printing stroke, to thereby avoid blurred impressions caused by an overprinting due to the rebounding of the printing hammer.

A specific object of the invention is to loosely mount a specified weight on the free end of a spring-actuated printing hammer to dampen the action of the printing hammer after it is rapidly returned to its normal position.

With these and incidental objects in view, the invention includes certain novel features of construction and combinations of parts, the essential elements of which are set forth in'appended claims and a preferred form or embodiment of which is hereinafter described with reference to the drawing which accompanies and forms a part of this specification.

Fig. 1 is a sectional View of one form of the invention, taken on line ll of Fig. 2.

Fig. 2 is a side view of one embodiment of the printin hammer and type carrier, together with the actuating mechanism for the printing hammer.

Fig. 3 is a sectional view of another form of the invention.

. Fig. 4 is a sectional view taken on line 44 of Fig. 5, and shows another form of the invention.

Fig. 5 is a fragmentary view of the form of invention shown in Fig. 4, together with a portion of the type carrier.

. Fig. 6 is a sectional view of another form of the invention.

Fig. 7 is a fragmentary side view of the form of the invention shown in Fig. 6, together with a portion of the type carrier.

, Fig. 8 is another form of the invention taken on line 88 of Fig. 9.

, Fig. 9 is a fragmentary side view of the invention shown in Fig. 8, together with a portion of the type carrier.

In general In printing hammer mechanisms of the type herein disclosed, the hammer is actuated by a. powerful spring, which when released forces the hammers against the type carriers with a sudden blow. In this form of printing mechanism, when the hammer falls back to its normal position it reacts against the driving spring, which causes the hammer to rebound, and in some instances this rebound is sufiicient to cause a second impression to be made. In the present application, one form of a spring-actuated mechanism is disclosed for the purpose of illustration; however many other forms of actuating mechanism may be provided, such as that shown in the patent to Robertson 1,613,129.

In order to prevent the rebound of the hammer, the present invention provides a loosely mounted weight on the free end of the hammer, which acts as a counteracting means to prevent the hammer from being actuated the second time, after the impression has been made. When the hammer is operated by its spring to effect a sudden blow on the type carrier the loosely mounted weight moves up against the under side of the hammer and when the hammer drops back to its normal position this weight drops to prevent the hammer from rising the second time. Fig. 1 shows a bar guided on studs as a counterweight. Fig. 3 shows a form of the invention in which powdered metal is used for the counterweight. Fig. 4 shows a round bar within the hollow head of the printing hammer. Fig. 6 shows metal shot in the hollow head of the printing hammer, and Fig. 8 is illustrated with mercury in the hollow head of the printing hammer. Whatever form the invention takes it is only necessary that the counterweight is loosely mounted so that it is free to move on the head of the hammer when the printing impact takes effect.

It has been found through experiment that the most eificient weight to be applied to the free end of the printinghammer should be equal to approximately 50% of the weight of the hammer when measured at the printing line of the hammer.

The present invention provides a simple and effective method of preventing the rebound, and eliminates the use of mechanism, such as arresting pawls, as shown in Robertson supra, thus simplifying the construction of the rebound preventing means.

Detailed description As illustrated in Fig. 2, the printing hammer I0 is pivoted on a stud II and normally rests on a plunger [2, which is actuated by a spring [3. The plunger l2 and spring l3 are carried by a flange I4 mounted on the frame of the machine. The printing hammer I0 is provided with a cam follower block I5 which engages a cam l6 mounted on a cam shaft IT. The free end of the hammer is provided with a rubber platen I8, which carries a ribbon and the record receiving means against the type carriers l9 when the printing hammer is impelled in a clockwise direction. The type carriers 19 are supported on a suitably located shaft 20.

As shown in Figs. 1 and 2, the printing hammer head 2| is provided with a pair of guiding studs 22, on which is loosely mounted a weight 23, the latter also having a noise-dampening material 24, mounted on the upper side thereof. The block 23 is loosely mounted on the studs 22, so that it can freely slide thereon.

When the machine is operated the cam I5, rotating in a counterclockwise direction, engaging the follower block 15, rotates the hammer l first in a counterclockwise direction, thus compressing a spring I3. When the step 25 of the cam 16 passes beyond the follower block 15, the spring [3 rapidly rotates the hammer ID in a clockwise direction around the shaft H to impel the hammer platen 13 against the type carrier by a sudden blow. The impact of the platen 18 against the type carrier suddenly arrests the hammer head 2!, which causes the block 23 to rise on the studs 22 until arrested by the underside of the head, whereupon the hammer lil immediately is restored toward its normal position. During this counterclockwise movement of the hammer head 2i the block 23 remains in contact with the underside of the hammer head 2i. When the hammer it strikes the plunger I2, the spring will be slightly compressed and the tendency will be to impel the hammer again in a clockwise direction and in some instances this clockwise movement is suflicient to make a second impression. However, at this moment the weight 23 drops, thus opposing the action of the counterclockwise movement of the printing hammer to prevent the second or rebounding printing from taking place.

Figure 3 shows a. modified form of the invention in which the head 2| of the printing hammer is hollow and contains the proper amount of powdered metal (ii. A plate 26 covers the opening 21 through which the powdered metal is inserted into the hollow opening of the head. During the operation of the printing hammer the powdered metal acts in the same manner as the blocks 23v to oppose the rebound action of the printing hammer,

Figs. 4 and 5 disclose a. still further modificae tion of the invention and show a steel rod 28 mounted in the hollow head of the printing hammer.

Figs. 6 and 7 show a still further modification of the invention, wherein the hollow head 2! of the printing hammer is provided with metal shot 29.

Figs. 8 and 9 illustrate a still further modification of the invention, wherein the hollow head 2| is provided with an appropriate quantity of mercury 36.

In each of the modified forms of the invention' the weights 28, 29, 3B or 3|, are maintained in the hollow head of the printing hammer by a plate 26, in the same manner as that described for the powdered metal in Fig. 3. In all forms, while the weights vary in character, they are all carried by the free end of the hammer and perform the same function.

While the form of mechanism herein shown and described is admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the one form or embodiment herein disclosed, for it is susceptible of embodiment in various forms all coming within the scope of the claims which follow.

What is claimed is:

1. The combination of an impression hammer, type carriers located above the impression hammer, an actuator to impel the hammer against the underside of the type carriers, said hammer thereafter being free to fall back from the type carriers, and a dampening means consisting of a weight freely carried by the hammer so that when the hammer is arrested by striking the underside of the type carriers the weight is impelled against the under side of a surface on the hammer to dampen the return movement of the hammer, said weight thereafter being free to fall gravitationally to prevent rebound of the hammer toward the type carriers.

2. The combination of a pivoted impression hammer, type carriers located above the impression hammer, an actuator to impel the hammer from a normal position to a position against the underside of the type carriers, said hammer thereafter being returned toward normal position, and a weight freely carried by the free end of the pivoted hammer for relative bodily movement of the weight in the direction of printing movement of the free end of the pivoted hammer when the hammer is arrested by striking the underside of the type carriers for taking an impression, said relative movement of the weight causing the weight to engage the hammer when the hammer returns toward its normal position, and said weight thereafter being free to fall back gravitationally to prevent rebound of the hammer toward the type carriers.

3. The combination of an impression hammer, type carriers located above the impression hammer, an actuator for impelling the hammer from a normal position against the underside of the type carriers, and a weight freely carried by the free end of the hammer, said weight being normally held in engagement with the hammer by gravitation, but being free to be impelled by momentum force in the direction of printing movement of the free end of the hammer to engage the hammer when the hammer returns toward normal position after an impression from the type carriers has been taken to prevent rebound of the hammer after the impression has been taken, said weight thereafter being free to fall back gravitationally.

4. The combination of an impression hammer, type carriers located above the impression hammer, an actuator for impelling the hammer from a normal position into a position against the underside of the type carriers, a hollow head on the hammer, and means loosely carried in the hollow head of the hammer acting as a weight, the cubic contents of said means being less than the cubic area of the interior of the hollow head to permit free movement of the means in the hollow head by momentum when the hammer is impelled against the underside of the type carriers, said moving means engaging the hammer as the hammer returns toward normal position, and said means thereafter being free to fall back gravitationally, to prevent rebound of the hammer after the impression has been taken.

5. The combination of an impression hammer, type carriers located above the impression hammer, an actuator for impelling the hammer from a normal position into a position against the underside of the type carriers, a hollow head on the hammer, and means comprising a plurality of discrete particles carried in the hollow head of the hammer, said means occupying less than all of the hollow space in the hollow head whereby the means is free to move within the hollow head by momentum when the hammer is impelled against the underside of the type carriers to take an impression, said moving means engaging the hammer as the hammer returns toward normal position, and said means thereafter bein free to fall back gravitationally, to prevent rebound of the hammer after the impression has been taken.

6. The combination of an impression hammer, type carriers located above the impression hammer, an actuator for impelling the hammer from a normal position into a position against the underside of the type carriers, and a dampening means consisting of a loose shiftable mass of material carried by said hammer, said mass shiftable relatively to the hammer in one direction by momentum when the hammer is impelled against the underside of the type carriers to take an impression, and said mass engaging the hammer as the hammer returns toward normal position, and said mass thereafter being free to fall back gravitationally, to prevent rebounding of said hammer after said impression has been taken.

7. The combination of an impression hammer, type carriers located above the impression hammer, an actuator for impelling the hammer from a normal position into a printin position against the underside of the type carriers, and inertia means normally held on the hammer gravitationally and movable with the hammer and also relatively to the hammer and acting on the hammer when the hammer changes its direction of movement to dampen oscillations of the hammer and prevent hammer rebound, said inertia means being free to fall back gravitationally when the hammer returns to its normal position.

8. The combination of an impression hammer, type carriers located above the impression hammer, an actuator for impelling the hammer from a normal position into a printing position against the underside of the type carriers, and inertia means normally held on the hammer gravitationally and movable with and also relatively to the hammer and acting on the hammer during their relative movements to dampen oscillations of the hammer and prevent hammeqrebound, said inertia means being free to fall back gravitationally when the hammer returns to normal position, said hammer having a platen at the free end thereof, and said inertia means being carried by the hammer adjacent the free end thereof.

9. The combination of an impression hammer, type carriers located above the impression hammer, an actuator for impelling the hammer from a. normal position below the type carriers into a position against the underside of the type carriers, a hollow head on said hammer, and a shiftable mass of material in said hollow head, said mass shiftable within said hollow head by momentum when the hammer is impelled against the underside of said type carriers, said mass thereafter being free to fall back gravitationally to prevent rebounding of said hammer after the impression has been taken and the hammer is restored to normal position.

10, The combination of an impression hammer, type carriers located above the impression hammer, an actuator for impelling the hammer from a normal position below the type carriers into a position against the underside of the type carriers, a hollow head on said hammer, and a shiftable mass of material in said head, said mass of material receiving an impetus of movement in the direction of the printing movement or the hammer within the hollow head when the hammer is impelled against the underside of the type carriers by said actuator, said mass dropping by gravity afte the impression has been taken and the hammer returns to normal position to prevent rebounding oi the hammer.

11. The combination of an impression hammer, type carriers located above the impression hammer, an actuator for impelling the hamme from a normal position below type carriers to a printing position against the underside of the type carriers, a hollow head on said hammer, and a mass of material in fluid state, occupying less than the entire hollow head so as to be movable therein by the force of momentum when the hamme is impelled against the underside of the type carriers, and said material acting by gravity to prevent said hammer from rebounding after the impression has been taken and the hammer returns to normal position.

HARRY M. WILLIAMS. JAMES E. JOHNSON.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 422,276 Wirshing Feb. 25, 1890 664,011 Beresford Dec. 18, 1900 1,073,340 Fu-rman Sept. 19, 1915 1,613,129 Robertson -Jan. 4, 1927 1,615,976 Going Feb. 1, 1927 1,652,057 Shipley Dec. 6, 1927 1,908,140 Going May 9, 1933 1,981,034 Gabrielson Nov. 20, 1934 2,117,451 Robertson May 17, 1938 2,199,265 Lohrey Apr. 30, 1940 2,204,187 Ostler June 11, 1940 2,208,050 Pasinski July 16, 1940 2,267,915 Henry Dec. 30, 1941 2,318,465 Chollar May 4, 1943 2,342,082 Klosterman Feb. 15, 1944 2,353,057 Mills July 4, 1944

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