AU617585B2 - Drill bit - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE Form ~Emw~ ~in -xl Short Title: Int. Cl: Vm" rm V Application Number: Lodged: Complete Specification Lodged: Accepted: Lapsed: Published: Poriority: Related Art: gi TO BE COMPLETED BY APPLICANT *Ott t Name of Applicant FISCHERWERKE ARTUR FISCHER GmbH CO. KG Address of Applicant: Waldachtal 3, D 7244 Tumlingen.

Federal Republic of Germany 0 "Atual Inventors: Artur Fischer and Willi Haug Address for Service: CALLINAN LAWRIE, Patent Trade Mark Attorney, 278 High Street, Kew, Victoria 3101, Australia.

Complete Specification for the invention entitled: "DRILL BIT" The following statement is a full description of this invention, including the best method of performing it known to me:- -1- The invention relates to a drill with a depth stop arranged on the drill shank.

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o* r*r r i tr c r r r r In order to produce drilled holes, the depth of which is to be accurately maintained, drills with a depth stop arranged on the drill shank are used. As the depth stop an integrally moulded collar can be used; however, when using a hammer drill, as the collar strikes against the wall surface it may cause damage in the region of the mouth of the drill hole. To produce drilled holes with an undercut at the bottom of the drilled hole, the use of drill bits of which the drill tip has lateral cutting edges projecting laterally beyond the shank is preferred.

Such drill bits can be chucked in hammer drills and are used to produce the drilled hoJe and the undercut. A depth stop that projects at he drill shank restricts the depth to which the drill bit can penetrate. A collar integrally formed with the «i shank can serve as a depth stop but when it comes into contact with the wall surface it strikes against this and may cause the mouth of the drilled hole to break up. During the swivelling op-eration, which is necessary for reaming out the undercut at the bottom of the drilled hole, particular consideration has to be paid to the fact that the depth stop is positioned against the wall surface of the masonry; damage to the wall surface can be caused by a rigid depth stop.

The invention is based on the problem of producing a drill bit, the depth stop of which avoids damage in the region of the mouth of the drilled hole.

In accordance with the present invention, therefore, there is provided a drill for producing drilled holes in masonry, said drill including: a drill shank; a depth stop mounted on said shank and including a resilient anti-vibration element; a drill bit tip having lateral cutting edges projecting laterally beyond said shank; bulge means formed on said shank between said resilient anti-vibration element and said drill tip; a collar formed on said shank above said resilient antivibration element; and a bearing washer arranged between said collar and said -2- -El, resilient, anti-vibration element, said resilient anti-vibration element being ringshaped and abutting said bearing washer.

Because the depth stop includes a resilient anti-vibration element, damage to the wall surface in the region of the mouth of the drilled hole, which may be caused by a rigid depth C o C o a E a oo o o.

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stop, is avoided.

A preferred embodiment of the drill bit according to the invention consists in that the depth stop comprises a resilient, ring-shaped anti-vibration element, which preferably consists of polyurethane or a corresponding plastics material. As the depth stop positions itself against the wall surface, the anti-vibration element is effective between the wall surface and a collar integrally formed with the drill shank, and absorbs the impacts coming from the hammer drill. Apart from this, the anti-vibration element has 4 sufficient resilience for the depth stop to lie full-face against the wall surface, in particular during tg I r the swivelling movement of the drill bit as an undercut S 15 drilled hole is being made. During the swivelling t's qmovement the anti-vibration element is, it is true, alternatingly resiliently deformed in accordance with the swivelling movement, but the contact face of the i depth stop lying against the wall surface does not change its position. The anti-vibration element has S c therefore not only the advantage that the wall surface t sustains no damage, but also the advantage that an I t 4 optimum contact area of the depth stop on the wall surface is maintained for reaming out the undercut.

Between the anti-vibration element and the collar S .integrally formed with the drill shank there is a bearing washer which substantially reduces the friction between the rotating collar and the anti-vibration element which, in contact with the wall surface, does not rotate with the collar. The bearing washer can be constructed as a metal washer or may consist of a plastics material with good sliding properties.

The anti-vibration element can be secured against axial displacement on the shank by a casing engaging over the collar formed on the drill shank. The casing may also completely enclose the anti-vibration element -3i_ 4 or engage the cylindrical side wall of the antivibration element so that the lower region of the anti-vibration element, being the contact face of the depth stop, projects freely in the direction of the drill tip. This last-mentioned embodiment has a soft contact face, as for the embodiment without an enclosing casing, whereby the wall surface in question is afforded particular protection.

A further development of the invention provides that the depth stop comprises a resilient, cup-shaped anti-vibration element which with its side wall engages I over a collar formed on the drill shank and has a base with a through-opening through which the drill shank o leading from the collar to the drill tip passes. The 15 anti-vibration element can simply be pushed over the drill tip up to the collar along the drill shank, the :r side wall of the anti-vibration element engaging over the collar being pushed over the collar by applying a little pressure. The anti-vibration element may also be manufactured as a on2-piece part from a resilient plastics material, for example from polyurethane.

t 'To reduce or avoid friction losses between the collar and the base of the anti-vibration element, a bearing washer that is arranged between the collar and the base inside the space enclosed by the anti-vibration element can be pushed onto the drill shank.

The invention is explained in detail hereinafter with reference to the drawing, in which: Figure 1 shows a first example embodiment of a drill bit with an anti-vibration element; Figure 2 shows a second example embodiment with a casing engaging over the anti-vibration element; Figure 3 shows part of a further example embodiment of a drill bit with the -i' lA -4- 05casing engaging the anti-vibration element laterally and Figure 4 shows a further example embodiment of a drill bit with a depth stop constructed as a resilient, cup-shaped anti-vibration element.

The drill bit 1 illustrated in Figure 1 has, integrally formed with the drill shank, a collar 2 against which a bearing washer 3 bears. Below the bearing washer 3 there is arranged an anti-vibration a element 4 which is a washer consisting of resilient oo oplastics material.

o Go, o.o The drill bit 1 has a drill tip 5 with lateral a OO Goeo 15 cutting edges 6, 7 projecting laterally beyond the drill 0° shank; the cutting edges serve in a manner known per Vasa se to produce an undercut at the bottom of a drilled hole. The drill shank has a bulge 8 which, inside the drilled hole, defines the pivot point when reaming out the undercut. The drill bit 1 lies with the widest o0o point 9 of the bulge 8 against the wall of the drilled 00 0 hole and allows itself to be swivelled about this pivot a point.

0*The collar 2, the bearing washer 3 and the antivibration element 4 together form a depth stop 10 which defines the maximum depth to which the drill bit 1 can 000G So 0 penetrate into masonry. As soon as the anti-vibration element 4 lies with its contact surface 11 against the wall surface 12 of the masonry 13, the drill bit 1, which is chucked in a hammer drill, not illustrated here, can be swivelled laterally in order to ream out the undercut 14 at the bottom of the drilled hole, Through the swivelling movement the collar 2 is inclined correspondingly towards alternate sides, the anti-vibration element 4 undergoing slight resilient deformation. The anti-vibration element 4 thus lies

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with its contact surface 11 full-face against the wall surface 12.

The drill bit 1 illustrated in Figure 2 has a depth stop 10 which consists of a collar 2, a bearing washer 3, an anti-vibration element 4 and a casing engaging over the anti-vibration element 4 and the collar 2. The casing 15 has an upper through-opening 16 and a lower through-opening 17 and for the rest is closed on all sides.

In Figure 3 the depth stop 10 also has a casing 18, the lower edge 19 of which is angled inwards and engages the cylindrical side wall of the anti-vibration o• element 4 laterally.

"S The bearing washer 3 is a metal washer, but a 00 0 So 15 plastics washer made of a plastics material with good 0000 sliding properties can also be used.

The drill bit 1 shown in Figure 4 has as its •roo depth stop 10 a resilient, cup-shaped anti-vibration element 20, and a collar 21 integrally formed with the drill shank. In the space between the base 22 of the ooo anti-vibration element 20 and the collar 21 there is a bearing washer 23, which can consist of metal or of a plastics material with good sliding properties. The anti-vibration element 20 is made of a resilient plastics material as a one-piece, approximately frustoconical part.

The anti-vibration element 20 has in its base 22 a through-opening 24 through which the drill shank with drilling dust grooves 25 and the drill tip 26 projects in a downward direction. The side wall 27 tapers upwardly, likewise the peripheral face of the collar 21.

The tapering peripheral face of the collar 21 has the same inclination as the tapering inner surface of the side wall 27 of the anti-vibration element The drill bit 1 illustrated can be chucked by the upper part of its shank in a hammer drill, not -6-

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r illustrated here, or in a similar apparatus. With the anti-vibration element 20 being positioned against a wall surface, the blows transferred from the hammer drill to the drill shank are so well absorbed that damage to the wall surface in the region of the mouth of the drilled hole is reliably avoided.

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Claims (9)

1. A drill for producing drilled holes in masonry, said drill including: a drill shank; a depth stop mounted on said shank and including a resilient anti- vibration element; a drill bit -ip having lateral cutting edges projecting laterally beyond said shank; bulge means formed on said shank between said resilient anti- vibration element and said drill tip; a collar formed on said shank above said resilient anti-vibration element; and a bearing washer arranged between said collar and said resilient, anti-vibrationL element, said resilient anti-vibration element being ring-shaped and abutting said bearing washer.

2. The drill as claimed in claim 1, further including casing arranged over said collar and engaging said resilient anti-vibration element. S.

3. The drill as claimed in claim 2, wherein said casing is mounted over said resilient anti-vibration element. f i

4. The drill as claimed in claim 2 or claim 3, wherein said resilient anti- vibration element has a side wall, said casing having end means laterally engaging said side all in such a manner that said resilient anti-vibration element has a lower portion projecting in a direction toward said drill tip beyond said casing.

The drill as claimed in any one of the preceding claims, wherein said resilient anti-vibration element is formed as a cup having a side wall engaging over said collar, and a base having a through-opening through which said drill shank extends.

6. The drill as claimed in claim 5, wherein said cup has a contour of a truncated cone.

7. The drill as claimed in any one of claims 4 to 6, wherein said side wall and said collar have conical peripheral surfaces.

8. The drill as claimed in any one of the preceding claims, further including a bearing washer located between said base and said collar. -8-

9. A drill for producing drilled holes in masonry, substantially as described herein with reference to the accompanying drawings. DATED the 9th day of September, 1991 Fischerwerke Artur Fischer GmbH Co. KG. by their Patent Attorneys CALLINAN LAWRIE i9 o o 0 S:9 -9-