US2822556A

US2822556A - Machine for slotting screw blank heads by means of a reciprocating cutting tool

Info

Publication number: US2822556A
Application number: US369066A
Authority: US
Inventors: Chiaia Paolo
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-04-14
Filing date: 1953-07-20
Publication date: 1958-02-11
Anticipated expiration: 1975-02-11

Description

Feb, 11, 1958 P. CHIAIA 2,822,556

MACHINE FOR SLOTTING SCREW BLANK HEADS BY MEANS OF A RECIPROCATING cumm TOOL Filed July 20. 1953 FIG.2

INVENTOR ATTORNEY United States Patent I MACHINE roiisrlorrmo sgREw BLANK HEADS gg ignANs OF A RECIPROCAITING CUTTING Paolo Chiaia, Milan, Italy Application July 20, 1953, Serial 1%. 369,066

Claims priority, application Italy April 14, 1953 3 Claims. (Cl. 10-6) The present invention relates to a screw blank head slotter which differs from conventional slotters in that it is provided with a reciprocating cutting tool instead of a circular saw.

In conventional screw head slotters the slot is cut by lowering onto said head a rotating milling cutter. Such a system generally presents the following shortcomings:

(a) A high tool cost;

(b) A facility for the cutters to break;

(c) The necessity of effecting the cutting with a coolant, which requires a drying operation.

To avoid such shortcomings, the machine according to the invention is characterized by the fact that the slot is cut in the screw blank head by means of an unvariable profile cutter reciprocating two or more times on the screw blank head, each time at a greater depth,-

vention is hereunder described by way of example with reference to Figures 1 and 2 of the annexed drawing, which show respectively a partially sectioned side elevation and a similar end elevation of the same.

The screw blanks 1 in which the slot is to be cut, are introduced into the intermittently rotating drum 2. By means of said drum 2 each blank 1 is individually brought in front of the tool 3 in the position 4, where it remains locked by a lever (not represented); all this being done through a known automatic mechanism which is, therefore, not described.

The tool 3 cuts the slot in the blank head 1 in the locked position 4 accomplishing with a reciprocating motion two or more strokes in unison with the guide cylinder or carriage 5 along shaft 6. The reciprocating movement of the tool is generated by cam 7 acting upon lever 8 connected by a double link 9 to carriage 5.

To increase at each passage the cutting depth of the tool 3, the latter is subjected at each passage to a greater pressure, obtained through the various steps of cam 10, operating push rod 11 and saddle 12 loaded by a spring 13 and push-rod 14 adjustably mounted on tool holder 15 fulcrumed at 16. Shaft 17 of cam is connected by means of a

gear train

18, 19, 20 and 21 to shaft 22 of cam 7 with such a ratio as to cause cam 7 to rotate during one rotation of cam 10 a number of revolutions corresponding to the number of steps of cam 10 plus one, that is, plus one turn corresponding to the time necessary for charging drum 2. Push-rod 14 is threaded in a boss 27 reciprocatable on a slide 25 by means of a screw 28 to vary the lever arm between fulcrum pin 16 and the tip of push rod 14, and the lever arm between the tip of push rod 14 and the slide 12. Thus the effect of the cam 10 can be increased or decreased to increase or decrease the feed of the tool 3 always with a same cam 10. V

As'the machine according to the invention is intended to be a universal one, that is, to take care of small 2,822,556 Pa en ed Fee, 5

and large screws; provision has been made to" vary' the number of strokes of thetool according to the size of the blank heads. j 5 V To this end; on shaft 1 7 aremoameq side by side severars'te'pp d cams 10, ofwh1ch only one-isinsight, each one of which presents a special pr'ofile' to' impart to the tool' 3 a differentnuniberofs'troke's; ,Tovary the num- 'ber of strokes it is sufliientto move over to the corresaid ratio, lever 23 which is loose on shaft 22 and carries loose gear 21 is axially displaced and its spring pin 24 is selectively introduced into a reference hole 25, thus automatically meshing loose gear 21 with one of gears 20.

The advantages of the screw blank head slotting machine provided with a reciprocating cutter, can be recapitulated as follows:

(a) The obtention of an absolutely straight bottom cut; I

(b) A remarkable cutter economy, as instead of costly short lived milling cutters, cheap plain easily made tools are used;

(c) The possibility of dry cutting, eliminating the subsequent tumbler drying of the blanks;

(d) The ease of regrinding the tools without the help of automatic machinery that is necessary for the milling cutters.

What I claim is:

1. A screw head slotter comprising a fixed-profile tool, means for feeding blanks successively to and retaining them at a work station, first cam-actuated means for reciprocating the tool in a rectilinear motion at and across the work station comprising a single-rise cam having a progressive slope followed by an abrupt termination and a dwell portion, second cam-actuated means for feeding the tool progressively toward the blank a predetermined amount for each stroke applied to that blank, and a gear train relating the movements of both cam-actuated means in a fixed cycle; the second cam-actuated means comprising a multiple-rise cam and a shaft whereon the multiple-rise cam is mounted, a dwell portion on said multiple-rise cam for controlling the retraction of the tool to enable indexing of the blanks at the work station; the gear-train comprising a first gear also mounted on the shaft and a last gear driving the first cam-actuated means, the gear ratio from first to last gears being such that for each rotation of the multiple-rise cam the first cam-actuated means are driven a number of times equal to the number of rises of the multiple-rise cam plus one.

2. A screw head slotter comprising ,a fixed-profile tool, means for feeding blanks successively to and retaining them at a work station, first cam-actuated means for reciprocating the tool in a rectilinear motion at and across the work station comprising a single-rise cam having a progressive slope followed by an abrupt termination and a dwell portion, second cam-actuated means for feeding the tool progressively toward the blank a predetermined amount for each stroke applied to that blank, and a gear train relating the movements of both cam-actuated means in a fixed cycle; the second cam-actuated means comprising a shaft and aplurality of multiple-rise cams respectively of different profiles mounted on the shaft, a dwell portion on each of said multiple-rise cams for'controlling the retraction of the tool to enable indexing of the blanks at the work station; the gear train comprising a first gear also mounted on the shaft, a last gear driving the first cam means, a set of intermediate gears respectively of different diameters mounted on a common counter-shaft and including a ment means operatively connected to the oscillating cam for oscillation thereby, second abutment means on the r 4 tool holder operatively connected to the oscillating slide for actuation thereby, and means for varying the relative positions of the two abutment means to vary the lever arms of the slide and pivoted tool holder.

References Cited in the file of this patent UNITED STATES PATENTS 1,025,305 Rasmussen May 7, 1912 1,217,396 Boerner Feb. 27, 1917 1,829,215 Fox Oct. 27, 1931