US2193721A

US2193721A - Expansion drill

Info

Publication number: US2193721A
Application number: US265813A
Authority: US
Inventors: Gunderson Chesley Ray
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-04-03
Filing date: 1939-04-03
Publication date: 1940-03-12
Anticipated expiration: 1957-03-12

Description

Mar'cblm. CIRGUNDERsON f .2,193,721-

EXPANSION DRILL Filed Apyil s., 1939 A' GR.GunZerJozz 3mm www 25 formed in the cutter part I6 of each blade member I5 so as to thereby form an adjustable blade extension means to limit the extension of the blade members I5 relative to the shank I 8. In the present instance, the coupling parts I of the blades I5 are pivotally mounted on a common pin 26, which extends through the parts I I a of shank ID and has the opposite ends thereof upsent as at 2l. As shown in Figure 2, the two cutouts I4 are disposed in spaced apart parallel relation, whereas in Figure 4 a slightly modified form of this construction is disclosed, the shank Illa being similar to every detail to the shank Iil with the exception that the outer end thereof is provided with a pair of slots Ma, which at their inner portions communicate one with the other and the two blades or bits I5o have their bearing portions Ia disposed in face abutting relation. In this instance, a tapered pin 2Go, is extended diametrically across the shank lita and through the two slots Ma. rThe opposite ends of the pin or shaft 26a may be upset or enlarged to prevent endwise movement thereof.

The sleeve 24 is locked in adjusted position on the shank I by means of a spring-pressed pawl 23 provided with a bill 29 engaging in a longitudinally extending groove or channel 3B formed in the part II of the shank I5. The pawl 2S is provided with an extension or iinger piece 3i projecting into a cutout 32 provided in the sleeve Z4 so that the pawl 23 may be rocked on the pivot 33 against the tension of the spring 34. 'Ihe pawl A2li is preferably countersunk in a suitable recess provided in the upper or outer end of the sleeve 24.

In the use and operation of this drill, the hole I3 is initially formed on the body of material I2 by any suitable form of drill, then the drill comprising the shank IU and the blades or bits I5 is inserted in the opening I3. Initially the two bits or blades I5 are disposed in collapsed or retracted position, as shown in dotted lines in Figure 1. If desired a hammer or impact device may be engaged with the opposite or inner end of the shank I0. Where a hammer or impact device is used the impact on the shank Ill will tend to spread the two bit members I5 apart at the bottom or inner end of the opening or hole I3. This action will continue until the two bit members I5 swing laterally to the limit permitted either by the abutments 22 or the bit controlling sleeve 24. When the two bits or blades I5 are in their extended position, similar to that shown in full lines in Figure l, finther impact or rotation of the shank IG and the bits or blades I5 will enlarge the bottom or inner end of the opening I3. In this manner a substantially large diameter pocket will be provided at the inner end of the opening I3 so as to admit of the insertion of either a toggle bolt or, if desired, blasting material may be inserted in the enlarged pocket and the outer portion of the opening I3 closed in the usual manner.

It has been found in actual practice that an enlarged pocket or recess formed by this drill will facilitate any blasting operations as this pocket will permit of a larger quantity of blasting material being positioned at the inner end of the hole and eliminate the action of any blasting material which at present extends toward the outer end of the opening I3.

Where the condition of the material permits,

the drill comprising of shank I0 and the two bits I5 may be connected to or mounted in a chuck or other rotating means so that the bits I5 may be rotated within the opening I3 at the same time that these bits are moved inwardly of the opening I3. By providing the abutments 22 at the outer end of the shank I0 and also providing an arcuate or substantially round socket I9 for the bearing portion I9 of each bit or blade I5, the strain applied to the shank IU by an impact device or rotating means is taken oI of the pin 26. In this manner the pin 26 will not be sheared off by reason of any strain applied to the shank I 0 and the bits I5.

Where it is desired to enlarge the pocket at the inner end of the opening I3 to a size substantially smaller than the complete extension of the two bits or blades I5 the sleeve 24 is threaded outwardly so that the outer end of the sleeve 24 forms an adjustable abutment engageable in the recesses 25 of each blade I5.

What I claim is:

l. In an expansion bit of that type including a pair of oppositely disposed blades each having a substantially circular inner portion and a cutter portion having a shoulder at its inner end, said bit comprising a shank having a threaded part intermediate .its ends and a non-threaded part extended outwardly from the outer end of said threaded part, said threaded part having its outer terminal portion formed with diametrically opposed substantially semi-circular cavities adapted to receive the inner portions of the blades, said non-threaded part being formed with a pair of oppositely disposed blade receiving cutouts in opposite sides thereof opening at its outer end and at spaced portions of its periphery, said cavities opening into said cutouts, each of said cutouts including an inner end wall formed with a curved part providing a continuation of the wall of a cavity adapted for engaging the edge of an inner portion of a blade, each of cutouts having its inner wall formed with an inclined part disposed at an obtuse angle to the said other part and constituting an abutment for engagement by the shoulder of a blade, and means extending through said non-threaded part and common to inner portions of said blades for pivotally connecting the latter to the shank.

2. The invention as set forth in claim l having the threaded part of the shank formed lengthwise thereof with a groove, an adjustable controlling member for the blades threadedly engaging with the threaded part of the shank, and

spring-controlled means carried by said member and correlating with said groove for latching said member in adjusted position.

3. In an expansion bit of that type including a pair of controllable oppositely disposed extendible and retractible blades, the combination of a shank provided intermediate its ends with a threaded part and a non-threaded part extending outwardly from the outer end of said threaded part, means for pivotally connecting the blades to said non-threaded part, said threaded part being formed lengthwise thereof with a groove, an adjustable controlling member for said blades threadedly engaging with the said threaded part, and spring-controlled means carried by said member and correlating with said groove for latching said member in adjusted position.

CHESLEY RAY GUNDERSON.