EP2318656B1 - Chisel holder having a weld as a wear protection element - Google Patents

Description

The invention relates to chisel holders for a cutting machine, road milling machine, surface miner or the like with a chisel holder that has an insertion opening and with a chisel support surface, at least one wear protection element being arranged in an area assigned to the chisel support surface.

Such a chisel holder is from the US 6,585,327 B2 known. The bit holder has a bore as a bit holder. The chisel can be used interchangeably. In the area of the hole entry, a hole extension is provided, into which hard metal rings are soldered. The chisel holder is aligned with the holes penetrating the hard metal rings. The chisel inserted in the chisel holder is supported with its chisel head on a chisel support surface of the facing hard metal ring.

At the same time, both hard metal rings also support the chisel in the area of its chisel shank and thus act as wear protection during operation. The use of hard metal material for the above-described purpose considerably increases the cost of production.

In addition to the high material price, a precise dimensioning of the receptacles and the absolutely flush fixing of the hard metal rings in relation to the chisel receptacle designed as a bore are required. The fixation is done by soldering. This requires a high amount of energy and thermal stresses are introduced into the tool holder in the soldering furnace. But even without these tensions, large hard metal parts tend to break very easily due to their extreme brittleness. Therefore, in the prior art, several smaller-sized hard metal inserts were installed on chisel holders, such as the one US 5,251,964 shows. As a result, the manufacturing effort required for the precise arrangement and alignment of the hard metal elements with respect to one another is increased still further.

Furthermore, from the DE 39 29 609 A1 a method is known in which the chisel support surface of the chisel holder affected by wear is protected by means of armor consisting of wear-resistant material. A powder mixed from hard metal particles and solder particles is melted onto the surface to be protected. The disadvantage here is that there is a non-flat surface that is not exactly orthogonal to the central longitudinal axis of the chisel holder. Such a surface protection then adversely affects the turning behavior of the chisel.

DE 39 29 609 A1 further discloses a bit holder with a bit holder designed as a bore. A shaft chisel can be received with its shaft in the chisel holder. The chisel holder is provided with hard metal reinforcement. DE 26 45 877 A1 discloses a chisel holder with a base body into which a chisel holder is inserted. The bit holder runs out in a cover surface of the bit holder. A weld seam is applied to the edge area of this cover surface for the purpose of protecting against wear.
It is an object of the invention to provide a chisel holder of the type mentioned at the outset which is protected effectively and with little outlay in terms of parts and production from the action of the chisel.
This object is achieved in that the at least one wear protection element is designed as a weld and is arranged at least in regions in at least one recess and that the recess is recessed into the bit support surface, or in that one or more grooves are designed as radial grooves and are set back with respect to the bit support surface.
The weld is formed by a filler metal that can be made in the recess with a low manufacturing effort using a conventional welding process. The weld is characterized by a high resistance to abrasion and thus sets the chisel or wear protection disc a high wear resistance. The wear properties of the tool holder can be adjusted to a large extent by choosing the appropriate welding filler material. In this way, wear-optimized chisel holders can be provided for different road surfaces to be processed (concrete, asphalt) or raw materials (coal, sandstone, salt, etc.).
Because the weld is accommodated in a recess provided for this purpose, surfaces that are required for error-free tool function and a long service life remain unaffected by the wear element.

According to the invention, the recess is designed as a groove. The groove can be made in the bit holder in a simple manner, for example by mechanical processing. Depending on the desired wear properties, almost any groove geometry can be manufactured. The wear can be controlled by choosing a groove cross section suitable for the application.
For example, it can be provided that the chisel support surface runs in a ring around the insertion opening and is arranged orthogonally to the central longitudinal axis of the chisel holder, and that the recess is recessed into the chisel support surface. The chisel support surface, which, as a geometric element of the chisel holder, guarantees the exact support of the chisel, is not functionally affected by the groove. The dimension of the recess in the groove can be selected in a material-optimized manner so that the wear limit for the bit holder is reached when the entire weld is processed.
If it is provided that the weld is flush with the chisel support surface, then the weld does not influence the exact chisel support and is, however, immediately available for starting operation.
According to the invention, it can also be provided that the weld is at least partially set back in relation to the bit support surface in the direction of the central longitudinal axis of the bit holder.

In this way, processing of the chisel on the chisel holder is permitted for a limited period starting from the start of operation. This enables these components to find their working position. Then, or increasingly, the wear protection effect of the weld begins. Another advantage is the easy manufacture of the weld.

In order to reliably ensure the free rotatability of the chisel with respect to the chisel holder, it can be provided that the recess runs around the insertion opening.

A possible embodiment of the invention can be such that the groove has a bottom wall and two groove walls adjoining it laterally at an angle, and that the groove side walls are parallel to one another. Then a constant wear resistance is opposed over the entire effective period of the weld.
However, it is also conceivable that the groove has a bottom wall and two groove side walls adjoining it laterally at an angle, and that at least one of the angles is greater than 90 °, so that a V-shaped groove geometry results, or that the groove in the Cross-section is U-shaped. It can be taken into account that the bit holder is worn as the wear increases. This results in changed force relationships on the bit holder, which can be taken into account with the groove geometries.

In addition, the expanding groove geometry has manufacturing advantages with regard to the reliable introduction of the weld.

Figur 1

in Seitendarstellung ein Meißelhalter-Wechsel-system mit einem Basisteil, einem Meißelhalter und einem Meißel;

Figur 2

in Seitendarstellung und im Vertikalschnitt das Meißelhalter-Wechselsystem gemäß Figur 1;

Figur 3

den in den Figuren 1 und 2 gezeigten Meißelhalter in perspektivischer Frontansicht;

Figur 4

eine vergrößerte Detaildarstellung des Meißelhalters gemäß Figur 3 in Seitenansicht und im Schnitt;

Figuren 5 bis 12

weitere Ausgestaltungsvarianten von Meißelhaltern gemäß Figur 3 in Seitenansicht und im Schnitt;

Figur 13

ein weiteres Meißelhalter-Wechselsystem;

Figuren 14 und 15

jeweils eine Draufsicht auf eine Meißelstützfläche eines erfindungsgemäßen Meißelhalters.

A chisel holder according to the invention can in particular also be designed in such a way that two or more grooves are machined into the chisel support surface, which run concentrically to the central longitudinal axis of the chisel holder, or that the weld or the welds has areas with different radial dimensions relative to the central longitudinal axis of the chisel holder. . With this measure, application-related uneven wear be counteracted. This effect can also be achieved, for example, with a chisel holder which is designed in such a way that the weld or the welds has areas which have different radial distances from the central longitudinal axis of the chisel holder.
A possible alternative to the invention can be such that one or more grooves are designed as radial grooves and are set back with respect to the chisel support surface.
As a result of the recessed arrangement, the chisel support surface remains unaffected during the manufacture of the weld. The radial groove can preferably be arranged in such a way that it can be seen from the outside and thus shows the state of wear as a wear mark.
The invention is explained in more detail below on the basis of exemplary embodiments illustrated in the drawings. Show it:

Figure 1

a side view of a tool holder change system with a base, a tool holder and a tool;

Figure 2

in side view and in vertical section the tool holder change system according to Figure 1 ;

Figure 3

the in the Figures 1 and 2nd shown chisel holder in a perspective front view;

Figure 4

an enlarged detail view of the bit holder according Figure 3 in side view and in section;

Figures 5 to 12

further design variants of chisel holders according to Figure 3 in side view and in section;

Figure 13

another bit holder change system;

Figures 14 and 15

each a top view of a chisel support surface of a chisel holder according to the invention.

The Figures 1 and 2nd show a bit holder changing system with a base part 10, a bit holder 20 and a bit 30.
As the Figure 2 can be seen, the base part 10 has a shaft receptacle 15 which, starting from a shoulder 12 or a base surface 14, is incorporated as a breakthrough in the base part 10.
A stop surface 13 adjoins the shoulder 12 at an angle. With the base surface 14, the base part 10 can be placed on the outer circumference of a milling drum tube (not shown) of a road milling machine. The base part 10 is welded to the milling drum tube. A thread receptacle 16, into which a pressure screw 17 can be screwed, opens into the shaft receptacle 15 counter to the tool feed direction.
The pressure screw 17 is used to fasten the chisel holder 20. The chisel holder 20 has an apron 21 which is coupled in one piece to a connecting section 23. The connecting section 23 carries a shoulder 22 which has a cylindrical section 24 projecting beyond the apron 23. The neck 22 and the cylindrical portion 24 are penetrated by a chisel receptacle 29 in the form of a through hole.
At its free end, the cylindrical section 24 forms a chisel support surface 26 which rotates in a ring shape and concentrically around the central longitudinal axis of the chisel holder 29. As the Figure 2 can be seen further, the chisel receptacle 29 merges into the chisel support surface 26 via an insertion chamfer 29.2 and a centering chamfer 29.1. The centering chamfer 29.1 expands the chisel holder 29 in a V-shape. The cylindrical extension 24 bears two wear marks 25. These are pierced as annular circumferential grooves in the outer contour of the cylindrical section 24 and are held parallel and spaced apart from the chisel support surface 26.

A cutout 41 which is essentially square or rectangular in cross section is machined into the chisel support surface 26. This recess 41 can be produced by mechanical processing (drilling, turning, milling) as an annular and concentric groove around the central longitudinal axis of the bit holder 29. This groove forms a bottom surface 44 which is parallel to the chisel support surface 26. Groove side walls 43.1 and 43.2 adjoin the bottom surface 44 at a right angle. The groove side walls 43.1 and 43.2 are set such that they are kept at a distance from the chisel receptacle 29 (and the insertion chamfer 29.2 and the centering chamfer 29.1) and the wear marks 25.

This means that these surfaces remain mechanically unaffected. A weld 40 is made in the recess 41. This completely fills the recess 41, an open surface 42 of the weld 40 being formed opposite the bottom surface 44 and being flush with the chisel support surface 26.

The recess 41 and its arrangement are selected such that the areas which are particularly important for a proper initial function of the overall system comprising the chisel 30 and the chisel holder 20, such as the chisel holder 29, the insertion chamfer 29.2, the centering chamfer 29.1 and the chisel support surface 26, are not formed from the weld are or are influenced by this functionally.

During operation, parts of the bit holder 20 can then be machined due to wear and the weld 40 can thereby be exposed in some areas. However, this then takes place in such a way that the weld 40 is ground in such a way that it can take over the task of the aforementioned functional surfaces without the tool being impaired. The bore outlet of the chisel receptacle 29 opposite the weld 40 opens into a counter surface 27. In the transition area between the counter surface 27 and the skirt 21, a plug-in extension 28.2 is formed on the chisel holder 20. With this plug-in attachment 28.2, the chisel holder 20 can be inserted into the plug-in receptacle 15 of the base part 10. The insertion movement is limited by the stop surface 13 against which the counter surface 27 strikes.

To fix the chisel holder 20 in the base part 10, the pressure screw 17 is screwed into the thread receptacle 16 until it is braced on a pressure surface 28.1 of the plug-in attachment 28.2. In the assembled state, a subsequent space 11 is formed between an underside 28 of the chisel holder 20 and the shoulder 12 of the base part 10.

A chisel 30, in the present case a round shank chisel, can be installed in the chisel receptacle 29. The round shank chisel has a chisel head 31 and a chisel shank 36 formed thereon. On the chisel shaft 36, a longitudinally slotted clamping sleeve 37 is axially captive, but can be rotated radially freely.

The chisel head 31 is provided with a cup-shaped receptacle in which a chisel tip 32 made of hard material is fastened. A circumferential pull-out groove 33 is incorporated into the rotationally symmetrical chisel head 31 and is delimited by a collar 34 on the shaft side.

In the transition area to the chisel head 31, the chisel shank 36 carries a wear disk 35 which is rotationally symmetrical and is provided on its side facing away from the chisel head 31 with a conically tapering centering collar 35.1. The outer diameter and the inner diameter of the wear plate 35 and the cylindrical section 24 correspond approximately. Likewise, the centering collar 35.1 of the wear plate 35 and the centering chamfer 29.1 of the chisel receptacle 29 correspond to one another in order to function properly, for. B. to ensure unimpeded chisel rotation of the entire system in use.

The chisel 30 is inserted into the chisel receptacle 29 in such a way that it is held therein by means of the clamping action of the clamping sleeve 37. The wear disc 35 rests on the chisel support surface 26 and the free surface 42 of the weld 40. The chisel head 31 is supported on the opposite side of the wear disk 35.

Due to the indispensable chisel rotation during operation, the wear disc 35 grinds over the free surface 42 and the chisel support surface 26 and processes them. It should be noted that only minimal signs of wear occur per life cycle of a chisel 30.

The weld 40 in particular counteracts rapid wear. The choice of the welding filler material allows the reaction to the special wear conditions of each individual application.

In the course of time, the cylindrical section 24 is nevertheless worked off, the state of wear being able to be determined optically by the position of the chisel support surface 26 in relation to the wear marking 25. After reaching the second wear mark 25, the bit holder 20 is to be replaced.

The Figure 9 shows that the weld 40 runs concentrically around the central longitudinal axis of the bit holder 29.

In the Figure 4 the weld 40 can be seen more clearly on an enlarged scale. The recess 41 is recessed into the chisel holder 20 to such an extent that the bottom wall 44 extends approximately to the height of the lower wear marking 25. Wear protection is thus ensured almost over the entire life of the bit holder 20.

The Figures 5 to 13 show chisel holders 20 corresponding to the chisel holders 20 Figures 1 to 4 correspond. They differ only in the design of the recess 41 or the weld 40.

According to Figure 5 the groove side walls 43.1, 43.2 of the recess 41 are arranged in a V-shape with respect to one another, the groove side wall 43.2 being axially parallel to the central longitudinal axis of the chisel receptacle 29.

In the Figure 6 a symmetrical V-shaped groove design is shown, with the opening angle (adjustment a groove side wall 43.1, 43.2 to the bottom wall) is preferably selected to be greater than 90 °.

According to the embodiment in the Figure 7 two annular welds 40 are used which are concentric about the central longitudinal axis. The welds 40 are essentially analogous to the weld 40 according to FIG Figure 4 educated.

Figure 8 illustrates an annular circumferential groove as a recess 41 which is semicircular or partially circular in cross section. This recess 41 is particularly easy to fill with the weld 40.

While according to the embodiments Figures 1 to 8 the free surface 42 of the weld 40 is always flush with the chisel support surface 26, illustrates the Figure 9 that all welds 40 can also have a free surface 42 set back with respect to the chisel support surface 26.

Figure 10 shows a weld 40, which is again in the form of a circumferential ring. However, the ring width running in the radial direction is varied in order to form a wear protection element which is matched to different load intensities.

The Figures 11 and 12th show the use of recesses 41 in the form of radial grooves. These are cut radially into the cylindrical outer surface of the cylindrical section 24.

When executing after Figure 11 is the upper groove side wall 43.1 spaced parallel to the chisel support surface 26, while the other groove side wall 43.2 is set at an angle.

Wear markings 25 occur in the transition area between the free surface 42 of the weld 40 and the cylindrical section 24. If the free surface 42 is analogous Figure 9 is designed, the wear marks 25 are clearly visible as transitions of the troughed area.
In the Figure 12 An exemplary embodiment is shown in which two recesses 41 arranged one above the other are used with welds 40 made therein. As the illustration illustrates, the welds 40 here can form outwardly protruding free surfaces 42 for identifying wear marks 25.

In the Figure 13 An embodiment is shown which is not part of the invention and which illustrates that the recess 41 can be formed not only in the form of a groove, but also as a recess.
Instead of circumferential welds 40, punctiform, arc-shaped or linear recesses 41 with welds 40 can also be provided, as exemplified in FIGS Figures 14 and 15 are shown. The only limitation for the shape and arrangement of the recess (es) is that they must be manufactured and filled again with the weld.
The described invention can be used and implemented simply not only in the chisel holders 20 shown in the drawings, but also in any other way in the chisel holders 20.

Claims (11)

1. A chisel holder (20) for a coal cutting machine, road milling machine, surface miner, or the like with a chisel receptacle (29) having an insertion opening and with a chisel support surface (26), wherein at least one wear protection element (40) is arranged in a region assigned to the chisel support surface (26)
   characterised in
   that the at least one wear protection element is designed as a weld (40) and is arranged at least in regions in at least one recess (41) formed as a groove,
   and that the recess (41) is recessed in the chisel support surface (26), or that one or more grooves are formed as radial grooves and arranged offset from the chisel support surface (26).
2. The chisel holder according to claim 1,
   characterised in
   that the chisel support surface (26) extends annularly around the insertion opening and is arranged orthogonally to the central longitudinal axis of the chisel receptacle (29).
3. The chisel holder according to claim 2,
   characterised in
   that the weld (40) is flush with the chisel support surface (26).
4. The chisel holder according to claim 2,
   characterised in
   that the weld (40) is arranged offset, at least in regions, from the chisel support surface (26) in the direction of the central longitudinal axis of the chisel receptacle (29).
5. The chisel receptacle according to any one of claims 1 to 4,
   characterised in
   that the recess (41) extends around the insertion opening.
6. The chisel holder according to any one of claims 2 to 5,
   characterised in
   that the groove has a bottom surface 44 and two groove walls (43.1, 43.2) laterally adjoining the same at an angle and
   that the lateral groove walls (43.1, 43.2) are at an angle to one another.
7. The chisel holder according to any one of claims 2 to 5,
   characterised in
   that the groove has a bottom surface 44 and two lateral groove walls (43.1., 43.2) laterally adjoining each other at an angle, and that at least one of the angles is greater than 90°, resulting in a V-shaped groove geometry, or that the groove is formed in the cross-section as a U-shape.
8. The chisel holder according to any one of claims 1 to 7,
   characterised in
   that two or more grooves are incorporated into the chisel support surface (26), which extend concentrically to the central longitudinal axis of the chisel receptacle (29).
9. The chisel holder according to any one of claims 1 to 8,
   characterised in
   that the weld (40) or the welds (40) has/have regions with different radial extent relative to the central longitudinal axis of the chisel receptacle (29).
10. The chisel holder according to any one of claims 1 to 9,
    characterised in
    that the weld (40) or the welds (40) has/have regions which occupy different radial distances from the central longitudinal axis of the chisel receptacle (29).
11. The chisel holder according to any one of the preceding claims,
    characterised in
    that the welds (40) introduced into the groove or into the grooves form wear marks.

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