JPS62242111A - Boring thread-cutting fastener - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to rotary screw fasteners of the type, particularly fasteners manufactured by a pair of forging dies.

Fasteners that drill and thread themselves are well known to those skilled in the art. Some of these fasteners are manufactured specifically by milling operations, others by forging methods using a pair of forging dies, and some fasteners are preferably manufactured by either of the aforementioned methods. A representative example of a punched and threaded fastener preferably made by forging is shown in U.S. Pat. No. 3,395,603. Fasteners made in accordance with the aforementioned patents are easy to use, do not require pre-drilling of holes in the structure in which they are used, and have found widespread acceptance; It has been proven that it can be produced in large quantities.

As the use of these self-drilling threaded fasteners increases, the requirement for reduced fastener drilling time becomes important, especially in the automotive manufacturing and metal assembly industries that use a large number of fasteners, especially when producing products with high volumes. This has become important when using a production line. Therefore, in developing an excellent threaded fastener of the self-drilling and thread-cutting type, the reduction of drilling work became a very important design factor.

It is therefore an object of the present invention to provide a punch-thread fastener that reduces drilling time over conventional punch-thread fasteners.

Furthermore, it is an object of the invention to provide a drilled and threaded fastener with which the drilling time can be improved, especially in the initial stages of the drilling operation.

It is still another object of the present invention to provide a punch-thread fastener that has better overall performance than conventional punch-thread fasteners.

These and other objects of the present invention are accomplished by providing a drilling and threaded fastener having a threaded shank and a guiding end having a pair of transverse axes that intersect on the centerline of the fastener. A pair of vertical grooves extend longitudinally on the guide end to form a pair of cutting surfaces, the cutting surfaces defining one of the aforementioned axes in cross section, and each of the cutting surfaces having a distal end. It is a cutting blade. The vertical grooves also form a pair of end faces concentrically with the centerline of the shank, each of which determines the radial range of one of the axes in any cross section of the guide end. A straight groove having an outwardly extending arcuate surface and having an arcuate cross-section is formed in each cutting surface near its cutting edge.

More particularly, the drilled threaded fastener has an axis determined by the cutting surface, the axis being longer than the axis determined by the arcuate surface of the end surface.

Also provided is a drilling and threaded fastener in which the groove extends the entire length of the cutting edge.

A pair of mating dies for forming a drilling and threaded fastener therebetween in a cold forging operation, each of the mating dies cutting into the workpiece by pressing the dies together against the workpiece during the cold forging operation. a portion arranged to form a surface, the end of the cutting surface forming a protrusion having an arched cross-section on the engagement surface of the mold, the protrusion forming a groove in the cutting surface during a cold forging operation; In order to do this, a pair of engagement dies are provided, which are characterized in that they extend from a portion forming the cutting surface to near the engagement surface.

A drilling and threaded fastener having a shank 12 with a continuous thread 14 formed thereon and a guide end 16 is shown in the drawings, particularly in FIGS. 1-4. The fastener 10 is generally symmetrical about the centerline of the shank 12, but has a major transverse axis vAx-x and a minor transverse axis Y-Y that meet at the centerline of the guide end 16. A pair of vertical grooves 18.20 are formed in the guide end 16 and extend longitudinally over the length of the guide end to define a pair of cutting surfaces 22.24. The cutting surfaces 22,24 extend along the major transverse axis and generally define the extent of the major transverse axis in any cross-section of the fastener.

Each end of said cutting surface 22.24 is provided with a cutting edge 26.
28, and the cutting edge forms an acute angle with respect to the centerline of the fastener 10. Said cutting blades 26, 28 are arranged to preliminarily penetrate into the metal surface in order to cut the guide end 16 of the fastener.

Each longitudinal groove 18.20 also defines a pair of end surfaces 30.32 that are concentric with the centerline of the shank 12. These end faces 30.32 each have an outwardly projecting arcuate surface 34.36 to define the radial extent of the minor transverse axis in any cross-section of the guide end 16.

As shown in FIGS. 1-4, each fastener 10 includes a pair of straight grooves 38.40 formed in the cutting surface 22.24 near the cutting edge 26.28. In the embodiment shown, the straight grooves 38.40 extend over the entire length of the respective cutting edge 26.28.

Referring to FIG. 5, the groove 38 has an arch-like cross section and is not necessarily a perfect circular arc. The action of the straight grooves 38, 40 (shown in Figure 6) is to create a continuous chip as shown in Figure 7, rather than the multiple small chips produced by conventional fasteners. The purpose is to allow the chips to flow smoothly along the vertical grooves 18, 20 and lead out of the holes made by the fastener.

In making the groove 38, it has been found that in order to maintain the integrity of the fastener, the depth D of the groove should be approximately 15% to 40% of the web thickness W, as shown in FIG. Ta.

Referring to FIG. 8, there is shown a die 50 which is one of a pair of engagement dies used to make the fasteners of FIGS. 1-4. Type 5° is based on the aforementioned US patent (S
1-7, but with the improvements described with reference to FIGS. 1-7.

The die 50 includes a portion 52 for forming a cutting surface 22 in the workpiece and a surface for forming the fastener guide end 16 in a forging operation, as is well known to those skilled in the art.

In order to achieve the object of the invention, said surface 52 and its mating type frequent surface are provided with a projection 54 arched in cross-section, which projection 54 is continuous with the surface 52 forming said cutting surface. The guide edge is designed to create a straight groove 38 when the fastener is formed during a cold forging operation. In the illustrated embodiment, at the end of the surface 52, the engagement surface of the mold that cooperates with the mold 5o becomes a straight portion 56, and the protrusion 54 extends along the line of the aforementioned engagement surface. This is the groove 38 of the fastener 10 described in FIGS. 1 to 4.
(or groove 40).

With the above configuration, the straight groove 38.4o provided on the cutting surface 22.24 of the guide end 16 has a small clearance angle at the tip and performs a planing action, thus shortening the drilling time and exhibiting excellent performance. The cutting surfaces 22, 24, each provided with a straight groove 38, 40, perform a drawing action on the tip of the fastener, which is very useful in the initial stages of the drilling operation.

As explained with reference to FIGS. 6 and 7, the cutting surface 22
．． The straight grooves 38, 40 formed in each of the holes 24 create a continuous chip that provides a mechanism for drawing the fastener tip into the material being drilled, thus providing superior drilling performance and reduced drilling time. .

[Brief explanation of drawings]

FIG. 1 is a front view of a punched and threaded fastener made according to the present invention, FIG. 2 is a side view of the fastener shown in FIG. 1 rotated 90 degrees, and FIG. FIG. 4 is a perspective view of the fastener shown in FIGS. 1 and 2, FIG. 5 is an enlarged sectional view taken along line V-V in FIG. Fig. 7 is a schematic diagram similar to Fig. 6 during the working of the fastener shown in Figs. 1 and 2; Fig. 8 is a schematic diagram used when forming the fastener shown in Figs. 1 and 2; It is a perspective view showing one of a pair of molds. 10...Zipper, 12...Shank, 14...
・Screw, 16... Guide end, 18... Vertical groove, 20
...Vertical groove, 22... Cutting surface, 24... Cutting surface, 26... Cutting blade, 28... Cutting blade, 30... End face, 32... End face, 34...・Archied surface, 36...
- Arched surface, 38... straight groove, 40... straight groove,
50... type, 54... protrusion. FIo, 4 F/(, IF7,
5

Claims (1)

Claims: (1) A drilled, threaded fastener comprising a threaded shank and a guide end having a pair of transverse axes that intersect on a centerline of the fastener, and a pair of manes on the guide end. extending in the longitudinal direction to form a pair of cutting surfaces, the cutting surfaces defining one axis of the pair of transverse axes in the cross section, and the distal end of the cutting surface forming a cutting edge; The groove further defines a pair of end surfaces concentric with the centerline of said shank, said end surfaces extending from said one end surface in any cross-section of said guide end.
a straight groove having an outwardly extending arcuate surface to define the radial extent of the other of the pair of transverse axes and having an arcuate cross section is formed in the cutting surface near the cutting edge thereof; A perforated and threaded fastener. (2) The fastener according to claim (1), wherein the axis determined by the cutting surface is larger than the other axis determined by the arched surface of the end surface. . (3) The fastener according to claim 1, wherein the groove extends over the entire length of the cutting blade. (4) The fastener according to claim (1), wherein the cutting blade is arranged at an acute angle with respect to the center line. (5) The fastener according to claim (4), wherein the groove extends over the entire length of the cutting blade. (6) Claim (5) The described fastener, wherein the axis defined by the cutting surface is greater than the other axis defined by the arcuate surface of the end face. (7) In a pair of engaging dies for shaping the guide end of a drilling fastener between them in a cold forging operation, each of the engaging dies presses the dies together against a workpiece during the cold forging operation. The cutting surface includes a portion disposed to form a cutting surface on the workpiece, the end of the cutting surface being a protrusion having an arched cross-section at the engagement surface of the die, and the protrusion forming the cutting surface during the cold forging operation. A pair of engagement molds extending from a portion where the cutting surface is to be formed near the engagement surface to form a groove on the surface.