GB2068435A - Improvements in or relating to cutting tools - Google Patents

Abstract

A combination of a cutting tool (1) having a shank (6) formed with a non-stick taper (12) together with a tool holder (2) provided with a complementary non-stick taper (34) enables, through the agency of a retaining means (42) the tool to be held firmly in the holder during use and to be easily released. <IMAGE>

Description

SPECIFICATION Improvements in or relating to cutting tools This invention concerns improvements in or relating to cutting tools and has particular, but not exclusive, reference to such tools for use in mining. In mining, especially coal mining, cutting tools are employed in large number to perform the task of removing the mineral from the seam face.

The tools or picks are mounted in holders secured to cutting members, for example in the form of rotatable drums.

Cutting tools are constructed having essentially two portions usually integral one with the other: a cutting portion which carries the hardened cutting edge or tip and a shank portion. The shank portion extends into and is secured in a socket formed in the tool holder. The means for retaining the tool shank in the socket can be of any suitable form and currently there are many different types available commercially.

One of the problems attendant upon the conventional combination of cutting tool and holder is the degree of slack therebetween and this has a disadvantageous effect in the operational cutting mode for when the tool encounters the material, impact loading occurs as between the tool and its holder. The parts which abut one another under this loading suffer considerable wear and eventually need replacement. The reason why it has been thought hitherto necessary to provide this degree of slack is to facilitate removal of the cutting tool from its holder; in this respect, it will be appreciated that the cutting edges or tips wear and as a consequence fresh tools are required to replace those worn through use.As this operation generally has to take place in situ on a cutting machine in difficult conditions, it is desirable to provide a combination of cutting tool and holder which can be disconnected one from the other without too much effort.

An object of the invention is to provide an improved combination of a cutting tool and a holder therefor.

Accordingly the invention provides a combination of a cutting tool and a holder therefor, the tool and the holder having complementary non-stick tapers, and retaining means for securing the tool in the holder such that in use the tool and the holder are retained firmly together through the contact between the complementary tapers.

A non-stick taper is one which is self-releasing from its complementary taper, that is a taper which will not stick. This is an important feature of the invention as it is necessary to ensure that after release of the retaining means the cutting tool and the holder can readily be parted. The angle of taper is advantageously in the range 1 70 to 450.

The retaining means are preferably of the quickrelease type which require no fixing operation other than the insertion of the cutting tool shank into the socket of the holder whereby upon engagement of the retaining means, securement is achieved automatically. A preferred type of quick-release retaining means comprises a resiliently loaded detent located in a wall of the socket of the holder, the cutting tool shank being provided with a depression or groove for receiving the detent. When the shank is initially inserted into the socket, the detent is depressed until it can frictionally engage with the depression or groove on the shank. Thereafter to remove the cutting tool from the holder, a suitable force is applied to the tool in order again to depress the detent to release the tool shank from engagement therewith.One such type of retaining means is described in GBPS 1167 714 which discloses a tool retaining device including, inter alia, a metal locking member provided with a resilient backing, the locking member projecting into the socket for engagement with a groove in the shank of the cutting tool.

The cutting tool of the present invention may be provided with a shank having a portion with the non-stick taper and a cylindrical end portion on which is formed a depression or groove.

Alternatively the whole of the shank is formed with the non-stick taper and a depression or groove is formed on the taper. An advantage of this latter alternative is that the bearing area of the tapers is increased and since the retaining means can be located higher up in the holder, the height of the holder can be of smaller dimensions.By way of example only, two embodiments of combination of cutting tool and holder according to the invention are described below with reference to the accompanying drawings in which: Figure 1 is a side view of a first embodiment of the combination; Figure 2 is a side view of the holder of the first embodiment; Figure 3 is a side view of the cutting tool of the first embodiment; Figure 4 is a scrap view of a detail of the first embodiment on an enlarged scale; Figure 5 is a side view of a second embodiment of the combination; Figure 6 is a side view of the holder of the second embodiment; Figure 7 is a side view of the cutting tool of the second embodiment; and Figure 8 is a scrap view of a detail of the second embodiment on an enlarged scale.

Referring to Figures 1 to 4, there is shown a first embodiment of a combination of a cutting tool 1 and a holder 2 therefor. The cutting tool 1 comprises a cutting portion 4 and an integral shank 6 with a protruding lip 8 formed therebetween. The cutting portion is provided in known manner and its free end with a hard metal insert 10 and at its base adjacent the shank 6 is of rectangular section to abut lugs on the holder 2 to prevent rotation of the tool 1. The shank 6 has a non-stick taper 12 and a chamfered cylindrical end part 14 which is provided with a groove 1 6, the groove having a sloping engagement surface 18.

The holder 2 is formed of a boss 30 having a socket 32 extending therethrough, the socket 32 being formed with a non-stick taper 34 and a cylindrical portion 36. A slot 38 opens into the socket 32 and into a bore 40 formed in the wall of the boss 30. Disposed within the bore 40 is a retaining means 42 having a metal locking member 44 which projects through the slot 38 into the socket 32, and a resilient backing 46 in which the locking member 44 is partially embedded.

The angle of the non-stick tapers 12 and 34 is 200. The shank 6 of the tool 1 is inserted into the socket 32 and the chamfered cylindrical part 14 of the shank 6 depresses the member 44 against the resilient backing 46 to allow further insertion of the shank into the socket. Upon protrusion of the member 44 into the groove 1 6, the tool 1 is henceforth releasably secured in the holder 2, the member 44 frictionally engaging the surface 18 of the groove as can more clearly be seen in Figure 4.

In this position wherein the tool 1 is held in the holder 2, the retaining means 42 hold the taper 12 of the cutting tool shank 6 tightly down onto the taper 34 of the socket 32, thereby preventing any relative movement between the two components.

In use, therefore, in a cutting mode as the tool presents itself to the mineral, there is no chatter, and therefore rigidity between the tool and the holder eliminates wear which has hitherto been caused by impact loading upon loosely abutting parts.

When it is desired to remove the tool 1 from the holder 2 an implement (not shown) is conveniently employed and can engage beneath the lip 8 and by appropriate leverage to overcome the resilience of the retaining means 42, the tool is extracted from the holder. Since complementary non-stick tapers are employed, release of the tool from the holder is easily executed notwithstanding tight seating of the tapers when the tool is in position in the holder in use.

Referring now to Figures 5 to 8, like numerals of reference have been given to like parts as those in Figures 1 to 4. The essential difference between the first and second embodiments is that the second embodiment incorporates a cutting tool 1 the shank 6 of which is formed solely of a nonstick taper 12 and the groove 1 6 for receipt of the retaining means 42 is located on the non-stick taper 1 2. This has the effects of making it possible to reduce the height of the tool holder 2 since the bore 40 for the retaining means 42 can be situated higher up in the holder wall. Furthermore, the bearing area of the tapers 12 and 34 is increased accordingly and thus can give an even more positive seating between the tool 1 and holder 2. The methods of insertion and extraction are the same for the second embodiment. Again, when the cutting tool 1 of Figures 5 to 8 is held within the holder 2, the retaining means 42 hold the two parts tightly together on their non-stick tapered bearing surfaces to give a rigid combination for the cutting mode.

It is to be understood that whilst one particular form of retaining means has been described, any suitable type of quick-release retaining means may be employed.

Claims (13)

1. A combination of a cutting tool and a tool holder therefor, the tool and the holder having complementary non-stick tapers, and retaining means for securing the tool in the holder such that in use the tool and the holder are retained firmly together through the contact between the complementary tapers.

2. A combination according to claim 1 in which the angle of the tapers is in the range 170 to 45 .

3. A combination according to claim 2 in which the angle of the tapers is 200.

4. A combination according to any one of claims 1 to 3 in which the retaining means is of the quick-release type.

5. A combination according to claim 4 in which the retaining means comprises a resiliently mounted detent mounted in the tool holder, the detent being engageable with a depression provided on the cutting tool.

6. A combination according to claim 5 in which the cutting tool is provided with a shank on which the non-stick taper is formed, and the depression is located on the tapered shank.

7. A combination according to claim 5 in which the cutting tool is provided with a shank on a part of which the non-stick taper is formed, the shank having a further cylindrical part in which is located the depression.

8. A combination according to claim 6 in which the detent projects into a socket of the tool holder, the socket being wholly formed with the non-stick taper.

9. A combination according to claim 7 in which the detent projects into a socket of the tool holder, the socket being partly formed with the non-stick taper and partly by a cylindrical section in which the detent is located.

10. A combination according to claim 8 or 9 in which the detent is so positioned in the socket of the tool holder as to ensure that the complementary tapers firmly bear one on the other when the detent engages the depression.

11. A combination of a cutting tool and a holder therefor substantially as hereinbefore described with reference to Figures 1, 2, 3 and 4 or Figures 5, 6, 7 and 8.

12. A cutting tool for use in the combination as claimed in any one of the preceding claims.

13. A cutting tool holder for use in the combination as claimed in any one of the preceding claims 1 to 11.