US3103833A

US3103833A - Apparatus for making screw drivers

Info

Publication number: US3103833A
Application number: US743247A
Authority: US
Inventors: Lejdegard Sixten Harald
Original assignee: BULTFABRIKS AB
Current assignee: BULTFABRIKS AB
Priority date: 1957-07-05
Filing date: 1958-06-20
Publication date: 1963-09-17
Anticipated expiration: 1980-09-17

Description

Sefit. 17, 133 s. H. LEJDEGARD 3,103,333

APPARATUS FOR MAKING SCREW DRIVERS Filed June 20, 1958 3 Sheets-Sheet 1 Fig. 1 Fig.2 Fig. 3 Fig.

Fig, 5 13 Sept-17,1963 s. H. LEJDEGARD 3303:8333

APPARATUS FOR MAKING SCREW DRIVERS Filed June 20, 1958 s Sheets-Sheet 2 Fig. 7

Sept. 17', 1963 LEJDEG'ARD 3,103,833

APPARATUS FOR MAKING SCREW DRIVERS Filed June 20, 1958 3 Sheets-Sheet 3 x! ll? United States Patent 3,103 833 APPARATUS Ft); MAIiiNG SCREW DRIVERS Staten Harald Lejdegard, Hailstahamrnar, Sweden, as-

signor to Buitfahriiis Airtieboiaget, Hallstaharnmar,

Sweden, a corporation of Sweden Filed June 29, 1958, er. No. 743,247 flairns priority, application Sweden July 5, 1957 3 Claims. (Cl. 76-1) The present invention relates to an apparatus for making screw drivers to be used with screws of the kind wherein the head is provided with a central, inwardly tapering re- .cess of for instance, star-like cross section such that the walls of the recess provide alternating grooves and ridges, with which the correspondingly shaped bit end of the screw driver engages.

The object of the invention is to provide a simple but nevertheless reliable apparatus for making screw drivers of the kind just mentioned.

To this end the present invention is characterized substantially by the fact that one end of a rod-shaped blank of a cross section materially differing from the desired final cross section is cold headed by means of tools movable towards and away from the blank into an appropriate basic form with respect to the number and the dimensions of said grooves and ridges, and is then given its final, tapering form by turning, grinding or a similar step.

Preferably, the blank when it is given said basic form and is removed from the tools which provide said form is held by means of tools which, upon the application thereof, will cold head the other end portion of the blank into a cross section which ensures the engagement with a handle or a machine. It is further preferred that the bit end portion of the blank, as a preparation for the cold heading into said basic form, is made conically tapering by a preparatory cold heading step. Thereby the blank may conveniently be provided with an annular flange at the transition from the conical portion to the remaining portion as it is cold headed into said conical form.

According to the above mentioned, an apparatus which is suitable for making screw drivers is characterized substantially by a tool comprising movable parts which are movable radially towards and away from the blank and are adapted to cold head one end of the blank into an appropriate basic form with respect to the number and the dimensions of the grooves and the ridges.

The invention will now be described in more detail with reference to the accompanying drawings, wherein FIG. 1 illustrates a blank for a screw driver;

FIG. 2 illustrates the blank after a preparatory cold heading step and a first cold heading step for shaping the bit end of the screw driver;

FIG. 3 illustrates the blank after a second cold heading step for shaping the bit end of the screw driver;

FIG. 4 illustrates a final screw driver;

FIG. 5 is an endview on a larger scale of the screw driver shown in FIG. 4;

FIG. 6 shows an apparatus for making screw drivers in its position immediately after the first cold heading step shaping the bit end of the screw driver;

FIG. 7 is a sectional view along line VIIVII in FIG. 6;

FIG. 8 shows a part of the apparatus in its position during the second cold heading step;

FIG. 9 shows the apparatus in its position immediately after the performance of the second cold heading step;

FIG. 10 is a perspective view, partly in section, of a part of the apparatus shown in FIG. 6.

The screw driver is made from a rod-shaped blank 11, preferably of round cross section. In a preparatory cold heading step the blank adjacent one end thereof is pro- "ice vided with a cross section which ensures its engagement with a handle or a machine in that the blank is provided with e.g. flutes 12 and ridges 13. In a first cold heading step for shaping the bit end of the screw driver this end portion is given a conical shape, as shown at 14, and at the same time the blank is provided with an annular flange 15, the object of which will be disclosed in more detail hereinafter, at the transition from the conical portion 14- to the remaining portion. Then, the blank is subjected to a second cold heading step whereby there are provided grooves 16 and ridges 17 in a desired number and with the desired basic dimensions. The annular flange 15, however, is not affected by this second cold heading step.

Sor far, the manufacture has been performed by cold heading, whereby, as is well known, considerable advantages are obtained as compared to shaping by cutting, grinding or the like. The screw driver still does not, however, have the tapering shape which is required for its engagement in the inwardly tapering recess in the screw heads. This shape, which is shown at 18 in FIG. 4, is obtained in a lathe or a grinding machine remote from the cold heading machine. For the conveyance of the blanks shown in FIG. 3 from the cold heading machine to e.g. the lathe, the annular flanges 15 are utilized and the blanks are conveyed depending between two parallel rails on which the annular flanges 15 are supported. The flanges are then removed in connection with the step in which the bit end 18 is given its tapering shape.

The apparatus shown in FIG. 6 consists of a holder 19 for the blank 11 with jaws 2h, 21 which are movable towards the blank. The jaws are adapted to cold head the screw driver into a cross section 1 2, 13 which ensures the engagement with a handle, as shown particularly in FIG. 7, and to hold the blank during the subsequent cold heading steps. The apparatus according to FIG. 6 further comprises a die 22, which is adapted to provide the blank with the conical end portion 14 and simultaneously with the annular flange 15. Finally, the apparatus according to FIG. 6 comprises a tool portion 23, which is adapted to cooperate with the holder 19 as will be described further hereinafter.

In the apparatus shown, a rod-shaped blank 11 is pushed into the holder 19 where it is clamped by means of the

jaws

20, 21 which at the same time brings about the flutes 12 and ridges 13 by cold heading. Thereafter, the holder is pushed against the die 22, whereby the conical portion 14 and the annular flange 15 will be formed, whereafter the holder 19 isretracted to its initial position, FIG. 6. Thereafter, the holder 19 is positioned opposite the tool 23 and pressed against this tool, FIG. 8, whereby the blank obtains the shape according to FIG. 3. Then, the holder 19 is retracted from the tool 23 and releases the blank 11 for conveyance to e.g. a turning lathe, wherea fter the holder 19 is returned to its initial position as shown in FIG. 6 in order to receive a new blank 11.

The tool portion 23, which is adapted to cooperate with the holder 19, consists of a slide 25, which is movable by means of the holder 19, against the action of a spring 24, FIG. 8, and in which there are arranged movable jaws 26 which are movable towards and away from the blank. The jaws are four in number in the example shown, but, of course, any other number and any shape of the jaws may be used. To eflect the movement of the jaws 26 towards the blank as the slide is pushed inwardly by means of the holder 19, the jaws 26 are arranged to cooperate with an inclined surface 27 on a ring member 28, which embraces the jaws and is stationary with respect to the slide 25. The jaws 26 will be pushed apart from each other by means of a conical pin 39 which is loaded by means of a spring 29, when they are released for movement apart from each other when the slide 25 is retracted from the stationary ring member 28.

The invention has been disclosed above with reference to a method for making a particular kind of screw drivers and resides in an apparatus for use in exactly that method. It will be understood, however, that other substantially similar articles may be made in a corresponding manner and that a great number of modifications and alterations as to details may be made within the scope of invention.

What I claim is:

1. An apparatus for making screw drivers and like articles having grooves and ridges from a blank solely by engagement with said blank which comprises a tool having movable parts adapted to receive the blank axially and which are movable radially towards and away from the blank from a plurality of sides and are adapted to cold head one end of the blank into an appropriate basic form with respect to the number and the dimensions of the grooves and ridges, a holder for the blank, said tool consisting of a reciprocable slide acted upon by a spring and which is adapted to be reciprocated against the action of said spring by means of said holder for the blank, said movable parts comprising a plurality of jaws which are movable radially towards and away from the blank in response to the movements of said slide, said jaws being disposed in said tool, an inclined surface on a stationary ring member embracing and cooperating with said jaws to cause said jaws to be moved towards the blank, and an axially-resilient, conical pin disposed to push the jaws apart when they are released for movement apart from each other as the slide is retracted from the stationary ring member.

2. An apparatus for making screw drivers and like articles having grooves and ridges from a blank solely by engagement with said blank which comprises a tool having movable parts adapted to receive the blank axially and which are movable radially towards and away from the blank from a plurality of sides and are adapted to cold head one end of the blank into an appropriate basic form with respect to the number and the dimensions of the grooves and ridges, a holder for the blank, said tool consisting of a reciprocable slide acted upon by a spring and which is adapted to be reciprooated against the action of said spring by means of said holder for the blank, said movable parts comprising a plurality of jaws which are movable radially towards and away from the blank in response to the movements of said slide, said jaws being disposed in said tool, an inclined surface on a stationary ring member embracing and cooperating with saidjaws to cause said jaws to be moved towards the blank, and an axially-resilient, conical pin disposed to push the jaws apart when they are released for movement apart from each other as the slide is retracted from the stationary ring member, the holder being provided with jaws which are movable radially towards the blank and arranged to hold the blank during the cold heading of one end thereof, said last-named jaws being adapted to be applied to the blank to effect a preparatory cold-heading step to give the blank a cross-section adjacent the other endthereof which ensures the engagement with a holding means.

3. An apparatus for making screw drivers and like articles having grooves and ridges from a blank solely by engagement with said blank which comprises a tool having movable parts adapted to receive the blank axially and which are movable radially towards and away from the blank from a plurality of sides and are adapted to cold head one end of the blank into an appropriate basic form with respect to the number and the dimensions of the grooves and ridges, a holder for the blank, said tool consisting of a reciprocable slide acted upon by a spri and which is adapted to be reciprocated against the action of said spring by means of said holder for the blank, said movable parts comprising a plurality of. jaws which are movable radially towards and away from the blank in response to the movements of said slide, said jaws being disposed in said tool, an inclined surface on a stationary ring member embracing and cooperating with said jaws to cause said jaws to be moved towards the blank, an axially-resilient, conical pin disposed to push the jaws apart when they are released for movement apart from each other as the slide is retracted from the stationary ring member, the holder being provided with jaws which are movable radially towards the blank and arranged to hold the blank during the cold heading of one end thereof, said last-named jaws being adapted to be applied to the blank to ellect a preparatory cold-heading step to give the blank a cross-section adjacent the other end thereof which ensures the engagement with a holding means, and a die adapted to preform the bit end of the blank by cold heading, said die being adapted to provide the bit end of the blank with a conical end portion and an annular flange at the transition from the conical end portion to the remaining portion during said cold heading.

References Cited in the file of this patent UNITED STATES PATENTS 916,215 Sullivan Mar. 23, 1909 1,936,339 Stevens Nov. 21, 1933 1,962,171 Bodor June 12, 1934 2,418,338 Dworkowski et al. Apr. 1, 1947 2,565,948 Cambern Aug. 28, 1951 2,627,192 Jenny Feb. 3, 1953 2,638,019 Stellin May 12, 1953 FORElGN PATENTS 959,118 France Sept. 21, 1949

Claims

1. AN APPARATUS FOR MAKING SCREW DRIVERS AND LIKE ARTICLES HAVING GROOVES AND RIDGES FROM A BLANK SOLELY BY ENGAGEMENT WITH SAID BLANK WHICH COMPRISES A TOOL HAVING MOVABLE PARTS ADAPTED TO RECEIVE THE BLANK AXIALLY AND WHICH ARE MOVABLE RADIALLY TOWARDS AND AWAY FROM THE BLANK FROM A PLURALITY OF SIDES AND ARE ADAPTED TO COLD HEAD ONE END OF THE BLANK INTO AN APPROPRIATE BASIC FORM WITH RESPECT TO THE NUMBER AND THE DIMENSIONS OF THE GROOVES AND RIDGES, A HOLDER FOR THE BLANK, SAID TOOL CONSISTING OF A RECIPROCABLE SLIDE ACTED UPON BY A SPRING AND WHICH IS ADAPTED TO BE RECIPROCATED AGAINST THE ACTION OF SAID SPRING BY MEANS OF SAID HOLDER FOR THE BLANK, SAID MOVABLE PARTS COMPRISING A PLURALITY OF JAWS WHICH ARE