EP0124575A1

EP0124575A1 - Drill construction

Info

Publication number: EP0124575A1
Application number: EP19830903601
Authority: EP
Inventors: Roland Naeslund
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-11-10
Filing date: 1983-10-31
Publication date: 1984-11-14
Also published as: WO1984001913A1

Abstract

Une structure de mèche comprend une mèche (Fig. 1) laquelle, afin d'éviter tout glissement dans un mandrin, possède de préférence trois rainures longitudinales espacées à égale distance (Fig. 2). La structure de mèche comprend en outre un cône de Morse (Fig. 3) modifié en ce sens qu'il possède une surface intérieure cylindrique (9) possédant des nervures longitudinales (12) ou des crêtes écartées entre elles de la même distance angulaire que les rainures de la mèche. Le diamètre interne du cône de Morse modifié correspond sensiblement à celui de la partie de fixation de la mèche assurant le centrage de cette dernière (Fig. 4). Le cône de Morse modifié et la mèche (Fig. 4) sont conçus de manière à empêcher la chute d'une mèche insérée dans le cône. A cet effet les rainures (5) peuvent avoir des surfaces d'extrémité en pente (6) agissant de concert par frottement avec des surfaces en pente (13) d'une extrémité des crêtes du cône. Le cône de Morse peut également présenter des parties de diamètre réduit.A bit structure includes a bit (Fig. 1) which, in order to prevent slipping in a mandrel, preferably has three longitudinal grooves spaced equally apart (Fig. 2). The wick structure further comprises a Morse taper (Fig. 3) modified in that it has a cylindrical inner surface (9) having longitudinal ribs (12) or ridges spaced therebetween by the same angular distance as. the grooves of the bit. The internal diameter of the modified Morse cone corresponds approximately to that of the fixing part of the drill bit ensuring the centering of the latter (Fig. 4). The modified Morse taper and drill bit (Fig. 4) are designed to prevent the dropping of a drill bit inserted into the cone. For this purpose the grooves (5) may have sloping end surfaces (6) acting in frictional concert with sloping surfaces (13) at one end of the peaks of the cone. The Morse cone can also have parts of reduced diameter.

Description

DRILL CONSTRUCTION

BACKGROUND OF THE INVENTION

This invention refers to a drill construction.

Conventional drills in general have a cylindrical, unhardened portion which is provided to be held by the chuck of a drilling machine or the like. There also exist drills having a Morses cone to fit into a corresponding socket of a drilling machine or the like.

To prevent the drill from skidding the drill has to be securely held by the chuck and the latter thus has to be effectively tightened. Since a proper tightening of a chuck necessitates a certain care and time it is often neglected and the result is that the drill and/or the chuck is often damaged by a drill rotating in the chuck.

One object of the invention is thus to eliminate these disadvantages in providing a drill which is effectively prevented from skidding also when the chuck has not been tightened as completely as would be necessary with a conventional drill.

Another object is to provide a drill construction including a Morses cone socket enabling the use of relatively cheap drills with the advantages of the Morses cone equipment.

Still further objects will be apparent from the attached specification and with reference to the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to fig. 1 numeral 1 designates a twist drill which is of a conventional design in that it comprises a spiral shaped portion 2 ending in a drill bit 3 and a cylindrical attachment 4. Additionally the drill according to fig. 1 and fig. 2 has three equidistantly spaced longitudinal grooves 5 extending from the free end of the attachment portion 4 and ending in a tapered portion 6. The tapered portions 6 incur no costs to provide when a grinding wheel is used to provide the grooves 5. The shape of the tapered portions is determined by the profile and radius of the grinding wheel.

Since conventional drill chucks have three equidistantly spaced jaws each having a tip shaped to hold the drill and since the grooves 5 have a section complementary to the tip sections of said jaws it is evident that the drill will be effectively prevented from skidding in the chuck also when the chuck is not tightened as much as would be necessary in respect of conventionally designed drills.

It is now common practice to make drills having a variety of drill diameters with a unitary dimension of the attachment 4. For instance a diameter of 1/2" of the attachement is used for drills from about 12 mm diameter to 24 mm diameter. This practice makes it very cheap to design the drills according to the invention since making the. grooves necessitates no alteration of grinding data from one drill dimension to another.

In professional work drills being provided with Morses cone are frequently used due to the effective holding of the drill and to the rapid way of shifting drills. However, such drills are expensive.

According to this invention a drill construction offering all the advantages of the conventional Morses cone constructions but at much lower costs and with less bulky drills have been achieved. To obtain this result a modified Morses cone according to fig. 3 is used with a drill according to fig. 1. The modified Morses cone in fig. 3 7 has like conventional Morses cones an outer tapered surface 8. It further has an inner surface 9 which, however, in this case is not tapered but cylindrical. Like conventional Morses cones it further has a planar upper portion 10 and a through elongated opening 11 serving as part of an arrangement to replace drills.

Thus, the first difference between the modified Morses cone 7 and a conventional one resides in the fact that the new Morses cone has a substantially cylindrical inner surface. A second difference is that the new Morses cone has three equidistantly spaced longitudinal splines or ridges 12 each of which having a tapered end portion 13 complementary to the end portions 6 (fig. 1) of the grooves 5 of the drill 1.

By inserting a drill 1 into the new Morses cone 7 the drill is attached to the cone by means of friction between the tapered portions 6 and 13. It is to be noted that the friction need only be sufficient to prevent the drill 1 from falling down when the drill is stading still or rotating. Of course it is possible to increase the grip by designing the cylindrical inner surface such that it in the region where the upper portion (fig. 4) of the drill is housed is tapered into a surface having a slightly reduced diameter and of course any kind of arresting means may be used to obtain the desired effect of just holding the drill in place. For instance it is possible to provide the Morses cone 7 with axially extending slots to obtain a gripping.

As soon as the drill is inserted in the described manner the drilling operations can take place and it is obvious that the pressure exerted upon the drill by the drilling operation further increases the grip between the drill and the Morses cone.

Although any kind of ejecting device can be used to remove the drill the frequently used method of inserting a wedge into the dpening 11 will in most cases be the most attractive one. Instead of arranging a number of Morses cones according to fig. 3 it is also possible to use only one such modified cone, i.e. one having a dimension to fit into the actual drilling machine. The Morses cones of smaller diameter can in such case be replaced by sockets having a cylindrical outer surface with grooves corresponding to the grooves 5 of the drills and with internal ridges.

It is apparent that the drills 1 can be used without restrictions in chucks, turret bushings, Morses cones modified according to fig. 3 and so forth and it is also apparent that such drills are much cheaper and less bulky than drills havingintegral Morses cones.

It is evident that the diameter of the inner surface 9 is so close to the diameter of the attachment portion 4 of the drill that the drill will be correctly centered when introduced in the modified Morses cone or the sockets just mentioned.

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DRILL CONSTRUCTION BACKGROUND OF THE INVENTION

This invention refers to a drill construction.

DESCRIPTION OF THE PREFERRED EMBODIMENT

It is now common practice to make drills having a variety of drill diameters with a unitary dimension of the attachment 4. For instance a diameter of 1/2" of the attachement is used for drills from about 12 mm diameter to 24 mm diameter. This practice makes it very cheap to design the drills according to the invention since making the grooves necessitates no alteration of grinding data from one drill dimension to another.

Thus, the first difference between the modified Morses cone 7 and a conventional one resides in the fact that the new Morses cone has a substantially cylindrical inner surface. A second difference is that the new Morse§ cone has three equidistantly spaced longitudinal splines or ridges 12 each of which having a tapered end portion 13 complementary to the end portions 6 (fig. 1) of the grooves 5 of the drill 1.

Although any kind of ejecting device can be used to remove the drill the frequently used method of inserting a wedge into the opening 11 will in most cases be the most attractive one. Instead of arranging a number of Morses cones according to fig. 3 it is also possible to use only one such modified cone, i.e. one having a dimension to fit into the actual drilling machine. The Morses cones of smaller diameter can in such case be replaced by sockets having a cylindrical outer surface with grooves corresponding to the grooves 5 of the drills and with internal ridges.

It is apparent that the drills 1 can be used without restrictions in chucks, turret bushings, Morses cones modified according to fig. 3 and so forth and it is also apparent that such drills are much cheaper and less bulky than drills having integral Morses cones.

Claims

WHAT I CLAIM IS:

1. A drill construction comprising a drill having a cylindrical attachment portion, said attachment portion having a number, preferably three, of longitudinal grooves, extending from the free end of said attachment portion.

2. A drill construction as claimed in claim 1 comprising in combination a drill, having a cylindrical attachment portion, having a number, preferably three, of longitudinal grooves, extending from the free end of said attachment portion and a modified Morses cone with an outer tapered surface and an inner substantially cylindrical surface, said inner surface having a number, preferably three, of longitudinal ribs or ridges having a section which is substantially complementary to the section of the grooves of said drill.

3. A drill construction as claimed in claim 1, wherein the grooves have tapered ends.

4. A drill construction as claimed in claims 1-2, wherein the ridges have tapered ends provided to form together with the tapered ends of the grooves of the drill a frictional holding grip between the drill and the modified Morses cone.

5. A drill construction as claimed in claim 2 wherein said modified Morses cone has at least one axially extending slot.

6. A drill construction as claimed in claim 2, wherein the inner surface of the modified Morses cone has an inner, preferably tapered, portion of a slightly reduced diameter provided to hold the drill by friction.

7. A drill construction as claimed in claim 2, wherein an ejecting device, preferably a through, elongated opening in said Morses cone and a separate wedge, is provided.

8. A drill construction as claimed in claim 1 and 2, wherein a cylindrical socket having internal equidistantly spaced longitudinal ridges and external longitudinal grooves, said socket being used with said drills and/or Morses cones.