GB2029761A

GB2029761A - A Milling Tool for a Milling Attachment Particularly for Milling off Road Surfaces

Info

Publication number: GB2029761A
Application number: GB7930082A
Authority: GB
Original assignee: ELFGEN APEX
Current assignee: ELFGEN APEX
Priority date: 1978-09-09
Filing date: 1979-08-30
Publication date: 1980-03-26
Also published as: DE2839292A1

Abstract

The invention relates to a milling tool for a milling attachment comprising a milling roller or milling disc 27, particularly for milling off road surfaces, the milling tool including a milling head 4 provided at one end of a shank 2 and a foot 1 provided at the other end of said shank end and having a larger cross sectional area shaped to be removably received in a holder 26 secured on said milling roller, or milling disc, wherein said foot is symmetrical on both sides relative to a center cross sectional plane A, and to the free end of which a further shank 3 including a milling head 5 is provided, and said holder is shaped, in the portion adjacent to said milling roller, or milling disc, to receive said further shank including said milling head. The tool can thus be reversed in the holder to position either head in an operative position. <IMAGE>

Description

SPECIFICATION A Milling Tool for a Milling Attachment Particularly for Milling Off Road Surfaces The invention relates to a milling tool for a milling attachment comprising a milling roller or milling disc, respectively, particularly for milling off road surfaces, the milling tool including a milling head provided at one end of a shank and a foot provided at the other end of the shank end and having a larger cross sectional area shaped to be removably received in a holder secured on the milling roller, or milling disc, respectively.

Prior art milling tools of this kind include a foot removably supported by a spring ring in a holder welded to the milling roller, or milling disc, respectively, a shank originating from the foot and a milling head provided on the shank. In a prior art milling tool, the milling head is shaped in the form of a hard-metal tip inserted into the hollow shank end and hard-soldered therewith. In accordance with an own older patent application, the shank is provided, at the end averted from the foot, with radial slots into which hard-metal plates are soldered in. In other prior art milling tools having an essentially rectangular cross section, there is provided, at the end of the shank, on one narrow side, a hard-metal plate which constitutes the milling head.

All these milling tools have in common the disadvantage that when the milling head has worn off, the remaining part of the milling tool, that is the foot and the shank, can no longer be used. Particularly in case of milling rollers provided with several hundreds of milling tools this leads to a disproportionately great waste of material per milled-off road unit and thus to high milling costs.

This disadvantage of the prior art milling tools is to be overcome by the invention. It is therefore the aim of the invention to provide a milling tool which permits a better utilization of the milling tool material. By correspondingly shaping the milling tool and, if necessary, the holder, it is particularly aimed at lowering the milling costs per milling path unit.

This aim is solved in accordance with the invention in that the foot is symmetrical on both sides relative to a center cross sectional plane, and to the free end of which a further shank including a milling head is provided, and the holder is shaped, in the portion adjacent to the milling roller, or milling disc, respectively, to receive the further shank including the milling head.

By this method of the invention, a double utilization of the foot of the milling tool is obtained, that is of that portion of the milling tool which includes a particularly great material volume. In view of the fact that the milling head requires the greatest proportion of the costs of the milling tool, a saving of about 20 percent is obtained for a double milling tool as compared to two individual milling tools. By correspondingly shaping the milling tool, the holder, and the means connecting them, the milling costs may be further reduced as will be shown later.

In accordance with an advantageous embodiment of the invention, the foot is provided with at least one annular groove symmetric relative to the center cross sectional plane to receive a retaining ring and the holder is provided with an undercut co-operating with the retaining ring. As, particularly when removing the milling tool from the holder, the groove, or the undercut, respectively, may be damaged by the retaining ring, it is advisable, if particular requirements are demanded from the fixation of the foot within the holder, to provide two annular grooves symmetric relative to the center cross sectional plane one of which is assigned to the one milling tool and the other to the other milling tool. The two annular grooves may cooperate with a single undercut provided in the holder. It is however also possible.

to provide each groove with a particular undercut in the holder. In case of the latter embodiment, a particularly safe connection is obtained, the production costs required therefor, however, are disproportionally high so that such an embodiment will be employed in special cases only.

As a retaining ring for the fixation of the foot within the holder, a spring ring may suitably be provided. As however, when removing the foot from the holder, the groove wherein the spring ring is located as well as the undercut in the holder may be damaged by a metal spring ring (this is particularly the case when spring rings having a rectangular cross section are used and if a material is used for the holder and the foot which is softer in comparison to the spring ring), a ring of rubber-elastic material is provided, in accordance with a further feature of the invention, as the retaining ring.In view of the fact that the milling roller, or milling disc, respectively, moves with a relatively low speed, and the milling tool is pressed into the holder when used, such a retaining ring of rubber-elastic material does not, or only insignificantly, reduce the safety of the fixation of the milling tool within the holder. A particular advantage of such a fixation of the milling tool in the holder is seen in that the milling tool may substantially easier and more rapidly be removed from the holder, and particularly without using any auxiliary tools, so that a change of the milling roller, or milling disc, respectively, is connected with substantially less costs. This however influences the milling costs.

It has proved to be particularly useful to employ a ring of hard-elastic material. Such a ring combines in a particularly favorable way the above described advantages in handling and the desired safety in the fixation of the milling tool within the holder. It has shown to be useful to provide a ring having a circular cross section.

With the aid of such a ring, a milling tool may particularly rapidly and easily be inserted into, and also removed from, the holder. If particular safety requirements are demanded from the fixation of the milling tool within the holder, be it that the milling roller, or milling disc, respectively, is to be operated with a relatively high speed, be it that the milling tools are relatively big and consequently heavy, it is advisable to provide a ring having a rectangular cross section.

In accordance with an advantageous embodiment of the invention, a groove is provided between the foot and each of the shanks with the front face averted from the milling roller, or milling disc, respectively, to receive an annular cover disc. The cover disc which is most suitably made of a rubber-elastic material avoids that dust, sand, and other small-grain milling material penetrates into the space between the holder and the foot, gets stuck there and jams the foot within the holder. Such a jamming effect is very frequent in prior art milling tools and renders the removal of the milling tool from the holder considerably difficult. By applying a cover plate, this effect may be eliminated and it may be safeguarded that the milling tool may be removed from the holder without any difficulties. This, too, has a reducing effect on the general milling costs.

In accordance with a further feature of the invention, the holder comprises a main portion secured to the milling roller, or milling disc, respectively, and a bushing which may removably be inserted into it, the interior of which being provided to receive the foot. By so-dividing the holder into two, it is possible to insert milling tools having different cross sectional dimensions into the holder. It is then only necessary to exchange the bushing provided for a certain milling tool cross section against a bushing required for the other milling tool cross section. In this way, the milling attachment may optimally be adapted to various road surfaces which results in an increase of the milling procedure speed, a reduction of the milling head wear, and an increase of the milling depth. The consequence is a reduction of the milling costs per milling path unit.In a preferred embodiment, the bushing is provided on the outer periphery thereof with a groove to receive a retaining ring and the main portion is provided with an undercut cooperating with the retaining ring. As the retaining ring, a spring ring again, or which is particularly suitable, a ring made of a rubber-elastic material may be employed. The latter ring will generally be preferred as it safeguards an easy insertion and removal of the bushing from the holder. It has proved to be particularly suitable to select the outer contour of the bushing identical to that of the milling tool foot. In this way, the opening in the holder provided for the bushing may at the same time be employed for the fixation of a milling tool.In other words, the milling tool having the greatest permissive cross sectional dimension may then be fixed within the holder without the aid of a bushing, while for all the other milling tools having a smaller cross sectional dimension corresponding bushings are inserted into the holder.

In an advantageous embodiment of the invention, each of the milling heads includes a number of radial slots wherein hard-metal plates operating as the cutters are provided. These plates are suitably combined to constitute a starshaped unit. Such an embodiment of the two milling heads has the advantage as compared to an also possible embodiment wherein each milling head includes a head portion completely made of hard metal that it is cheaper and the milling costs per milling path unit are thus smaller in case of a milling head including a head portion completely made of hard metal.

It has proved to be suitable to provide each of the two milling heads conical independent from its structure. Under certain circumstances, it may also be advantageous to shape one milling head conical and the other cylindrical. In this way, one can obtain a milling tool having two differently shaped milling heads one of which may for instance be particularly employed for road surfaces of asphalt and the other particularly for road surfaces of concrete. By changing the double-head milling tools, the milling attachment may be adapted to the corresponding road surface conditions on the spot without any difficulties. For the same reasons, it is advisable to select, in the case of milling heads having radial slots and hard-metai plates arranged therein, the number of the cutting edges on the two milling heads different.It may as well be advantageous to provide the two milling heads with different hardmetal materials. These above mentioned features may be realized individually as well as in combination. The embodiment of the two milling heads different in shape, material, number of cutting edges and so on permits that, with the aid of two different clases of double milling tools, all existing road surfaces may optimally be milledoff, the adaptation of the milling attachment to the existing road surface being possible rapidly and without any difficulties. The resultant substantial milling cost decrease is obvious.

The invention will now be explained in more detail based on the drawings which include, partly in schematic representation, exemplified embodiments of the present invention.

Figure 1 is a lateral view of a milling tool having two identical milling heads.

Figure 2 is a lateral view of a milling tool having two different milling heads.

Figure 3 is a lateral view of another milling tool having two different milling heads.

Figure 4 is a lateral view of another milling tool having two identical milling heads.

Figure 5 is a lateral view, partly in cross section, of a milling tool according to Figure 1 in a holder.

Figure 6 is a lateral view, partly in cross section, of a milling tool according to Figure 1 in a holder, the milling tool having two annular grooves.

Figure 7 is an exploded view of a holder, bushing provided therefor, and a milling tool according to Figure 1. The milling tool shown in Figure 1 comprises a foot 1 which is symmetrical on both sides relative to a center cross sectional plane A and passes over, at each of the two front sides thereof, into a shank 2 or 3, respectively, each of which carries at the free end thereof a milling head 4 or 5, respectively. Each of the two milling heads 4 and 5 is provided with four radial slots 6 each one staggered relative to the other at 900 wherein one hard-metal plate 7 each is provided. All four hard-metal plates 7 constitute one integral star-shaped unit. The unit is connected, by hard-soldering, to milling head 4 or 5, respectively. Symmetrically relative to the center cross sectional plane A, there is provided an annular groove 8 to receive retaining ring 9 (compare Figure 5).Between foot 1 and each of shanks 2 or 3, respectively, there is provided a further annular groove 10 or 11, respectively, each, into which an annular cover disc 12 (compare Figure 5) may be inserted.

The structure of the double milling tool of Figure 2 is, in principle, the same as of the earlier described milling tool. Only the two milling heads 13 and 14 are different from those of the milling tool according to Figure 1. In case of milling head 13, the individual hard-metal plates 7 extend beyond the conical contour of the shank end while in the former case they closed with this contour. Milling head 14 is moreover differently designed as compared to milling head 13: it possesses a plane front face 1 5 including four slots 1 6 each staggered relative to the other at 900 into which again four hard-metal plates 17 of about rectangular dimension are soldered-in.

Plates 1 7 constitute again an integral star-shaped unit and extend, with their free longitudinal edges beyond front face 1 5.

In Figure 3, a double milling tool is shown wherein shank 2 passes over into a conical milling head 4 which includes four plates staggered relative to each other at 900 while shank 3 passes over into a conical milling head 18 which includes three plates staggered relative to each other at 1200. The remaining structure of the double milling tool corresponds to that of Figure 1.

In the double milling tool shown in Figure 4, each of the two shanks 2 and 3 is provided with a recess 1 9 or 20, respectively, into which a head portion 21, or 22, respectively, completely consisting of hard metal may be inserted each.

Each of the two head portions 21 and 22 possesses a conical end portion 23 or 24, respectively, which constitutes the milling head.

To fix the above-described milling tool to a milling roller 25, or milling disc, respectively, a holder 26 is provided, which is welded onto the outer surface 27 of milling roller 25. Holder 26 is provided, at about the middle, with an inner shoulder 28 through which holder 26 is subdivided into a space 29 to receive shank 3 with milling head 5 and a space 30 to receive foot 1. The side of shoulder 28 directed to foot 1 is provided with a bevel 31 upon which bevel 32, or 33, respectively, provided on the foot may rest. In the space 30 of holder 26 a groove 34 is provided the front edge of which forms an undercut 35.

Groove 34 is adjacent to groove 8 in foot 1 so that the retaining ring 9 which consists of rubberelastic material is pressed into the two grooves 8 and 34 and thus foot 1 is solidly fixed within holder 26 so that it can only be withdrawn from holder 26 against a force acting in the direction of arrow R.

The length of space 30 of holder 26 is so designed that front side 36 of the space closes with the side face of groove 10 adjacent foot 1. In this groove, cover disc 12 is provided consisting of rubber-elastic material and protecting space 30 against the penetration of dust and small milledoff particles from the outside.

In the embodiment according to Figure 6 there are provided, in foot 1 of the milling tool, two annular grooves 37 and 38 symmetrically arranged relative to the center cross sectional plane A. one of which cooperates with groove 39 or an undercut formed by this groove 39, respectively, asymmetrically provided, relative to the center cross sectional plane A, in holder 26.

Groove 37, or 38, respectively, again serves to receive a retaining ring 9 of rubber-elastic material.

In Figure 7 a two-partite holder 41 is shown comprising main portion 26 and bushing 42 which may removably be secured within main portion 26. Bushing 42 is provided on the outer periphery thereof with an annular groove 43 and at one of the ends thereof with a bevel 44. The dimensions and the position of groove 43 and bevel 44 are so selected that groove 43 corresponds to groove 8 in foot 1 of the milling tool and bevel 44 corresponds to bevel 32, or 33, respectively, of the milling tool. This means that when inserting bushing 42 into the main portion 26 of the holder, groove 34 provided in holder 26 corresponds to groove 43 and bevel 44 comes into contact with bevel 31. The fixation of bushing 42 within holder 26 is obtained by means of retaining ring 45, which engages into the two grooves 34 and 43 and which may be made of a rubber-elastic material.Into bushing 42 a milling tool, smaller relative to the cross sectional dimensions thereof, may be inserted. For this purpose, bushing 42 is provided with a shoulder 46 having on the side directed to foot 1 of the milling tool a bevel 47. In the range of groove 43 there is, in the interior of bushing 42, furtheron a groove 48, which cooperates with groove 8 of the milling tool and wherein retaining ring 9 is provided. As to the effect, shoulder 28 of holder 26 corresponds to shoulder 46 of bushing 42, bevel 31 of holder 26 to bevel 47 of bushing 42, and groove 34 in holder 26 to groove 48 in bushing 42. A milling tool of a greater cross sectional dimension can therefore directly be inserted into holder 26 without bushing 42 as is for instance shown in Figure 5, while a milling tool having a smaller cross sectional dimension than the interior dimension of holder 26 may be inserted into it by means of a bushing 42. The wall thickness of bushing 42 depends on the difference of the cross sectional dimension of foot 1 of the milling tool and the interior cross sectional dimension of holder 26 within the range of space 30.

Claims

1. A milling tool for a milling attachment comprising a milling roller or milling disc, respectively, particularly for milling off road surfaces, said milling tool including a milling head provided at one end of a shank and a foot provided at the other end of said shank end and having a larger cross sectional area shaped to be removably received in a holder secured on said milling roller, or milling disc, respectively, wherein said foot is symmetrical on both sides relative to a center cross sectional plane, and to the free end of which a further shank including a milling head is provided, and said holder is shaped, in the portion adjacent to said milling roller, or milling disc, respectively, to receive said further shank including said milling head.

2. A milling tool according to claim 1, wherein said foot is provided with at least one annular groove symmetric relative to said center cross sectional plane to receive a retaining ring and said holder is provided with an undercut cooperating with said retaining ring.

3. A milling tool according to claim 2, wherein two annular grooves symmetric relative to said center cross sectional plane are provided.

4. A milling tool according to claim 2 or 3, wherein a spring ring is provided as said retaining ring.

5. A milling tool according to claim 2 or 3, wherein a ring of rubber-elastic material is provided as said retaining ring.

6. A milling tool according to claim 5, wherein a ring of a hard-elastic material is provided.

7. A milling tool according to claim 5 or 6, wherein a ring having a circular cross section is provided.

8. A milling tool according to claim 5 or 6, wherein a ring having a rectangular cross section is provided.

9. A milling tool according to one of claims 1 through 8, wherein between said foot and each of said shanks a groove with the front face averted from said milling roller or milling disc respectively, is provided to receive an annular cover disc.

10. A milling tool according to claim 9, wherein said annular cover disc is of a rubberelastic material.

11. A milling tool according to one of claims 1 through 10, wherein said holder comprises a main portion secured to said milling roller or milling disc, respectively, and a bushing which may removably be inserted into it the interior of which being provided to receive said foot.

12. A milling tool according to claim 11, wherein said bushing is provided on the outer periphery thereof with a groove to receive a retaining ring and said main portion is provided with an undercut cooperating with said retaining ring.

13. A milling tool according to claim 12, wherein the outer contour of said bushing is selected to be identical to that of said milling tool foot.

14. A milling tool according to one of claims 1 through 13, wherein each of said milling heads includes a number of radial slots wherein hardmetal plates operating as cutters are provided.

15. A milling tool according to claim 14, wherein said individual plates are combined to constitute a star-shaped unit.

1 6. A milling tool according to one of claims 1 through 13, wherein each milling head includes one head portion completely of hard metal.

17. A milling tool according to one of claims 14 through 16, wherein each milling head is conical.

1 8. A milling tool according to one of claims 14 through 1 6, wherein one of said milling head is conical and the other of said milling heads is cylindrical.

19. A milling tool according to claim 14 or 15, wherein the number of cutting edges on said two milling heads is different.

20. A milling tool according to one of claims 14 through 19, wherein said hard-metal material on said two milling heads is different.

21. A milling tool substantially as hereinbefore described with reference to, and as illustrated by, Figures 1, 2, 3, 4, 5, 6 or 7 of the accompanying drawings.