EP1956186A2 - Hard metal tip for a round shank pick - Google Patents

Abstract

The tip (1) has a body (4) with twelve sliding surfaces that are formed at projections and including an inclination opposite to a longitudinal axis (2) of a round shank chisel. The tip is formed around the axis in a radial symmetrical manner and conical to a base area (5) over the body. The sliding surfaces run parallel to each other from a head (3) to the base area and are coiled as thread-like around the axis, where the projections are formed with respect to a plane by the axis in a mirror-symmetrical manner.

Description

The invention relates to a hard metal tip for a round shank chisel, which is halterbar by means of a chisel holder on a rotatable roller of a milling machine, wherein the hard metal tip is radiärsymmetrisch starting from a tip over a body to a foot portion substantially conical and about a longitudinal axis of the round shank chisel and wherein the Corpus from the top to the foot area substantially parallel to each other extending raised guide surfaces.

Generic carbide tips are made for example DE 34 42 546 A1 and DE 198 57 451 A1 known. The known carbide tips have with respect to the longitudinal axis in the radial direction inclined guide surfaces. US 5,32A, 098A discloses a hard metal tip having bump-like protrusions inclined in a radial direction with respect to the longitudinal axis to improve powder metallurgy formability. Round shank bits with such carbide tips are used in a generally known manner for the abrasive machining of, for example, asphalt or concrete surfaces by means of rotating cylindrical milling drums. The round shank bit is aligned with its tip pointing outwardly on the surface of the milling drum and against a radial direction of the roller at the mounting location so inclined that its longitudinal axis with a circumferential direction of the roller at this location an angle between five and 45 degrees and angle with a circumferential plane encloses an angle of about seven degrees of angle through a circumference of the roller.

As a result of the inclination relative to the circumferential plane, the carbide tip rolls upon engagement with the material with a proportion of movement in the circumferential direction of the round shank chisel on the material, so that the round shank bit is rotated about its longitudinal axis. This rotation of the round shank chisel should ensure uniform wear and thus optimum service life of the carbide tip. Without a rotation of the bit or the hard metal tip, the latter would "start up" within a short time, ie wear out on one side, so that the effective wedge angle would be worsened and the cutting power drastically reduced. The known generic carbide tips already provide a significant improvement in rotation compared to a non-profiled carbide tip which is generally known in the wider field of the invention;

The rotation about its longitudinal axis is impressed on the round shank bit in the form of a torque when rolling off the hard metal tip by the material to be removed. This torque is produced by a force acting on the hard metal tip in its circumferential direction, namely, by a force acting in the circumferential direction of the carbide tip of a force acting on the hard metal tip in the forward drive direction of the milling drum, ie in a circumferential direction of the milling drum, which is already at unprofiled carbide tips the static friction in contact with the material to be removed results.

Improved rotation of the round shank bit is generally achieved by increasing the torque around the bit axis. The known carbide tips increase by means of the relative to the circumferential direction of the milling drum with the longitudinal direction of the carbide tip inclined baffles the adhesion of the carbide tip in contact with the material to be removed and thus acting in the circumferential direction of the milling drum on the carbide tip force: In addition to the frictional forces generated at the fins , which dig at least in beginnings in the material to be removed, in positive engagement with this material compressive forces that exceed the frictional forces on unprofiled "smooth" carbide tips by a multiple.

These compressive forces correspond to the resistance of the material to be removed from displacement in the direction in which the guide surfaces move - ie in the feed direction of the milling drum - and - neglecting the frictional forces generated by them - substantially perpendicular to the guide surfaces. The proportion of these resistance forces acting perpendicular to the guide surfaces is about twelve percent due to trigonometric relationships in the known carbide tips and the usual inclination between about three and seven degrees of angle with respect to the circumferential plane of the milling drum. Further improvement of the rotation of the round shank chisel by increasing the proportion of compressive force acting perpendicularly on the guide surfaces of the known carbide tips would require a greater inclination relative to the circumferential plane. For functional reasons, however, the inclination of the round shank chisel relative to the peripheral plane should generally not exceed this value. Because with increasing angle of attack, the power loss during Zerspannungsvorgang increases significantly, since the effective during splitting process angle are less favorable inside and an increasing proportion of the drive power of the milling drum in friction, ie heat is converted.

task

The invention has for its object to further improve the rotation of the round shank chisel.

solution

Starting from the known carbide tips is proposed according to the invention that the guide surfaces are coiled around the longitudinal axis thread. With the thread-like spiraling around the longitudinal axis of the round shank chisel, the guide surface located in engagement with the material to be removed is set at an angle relative to the circumferential plane of the milling drum, regardless of the inclination of the round shank chisel. Due to the trigonometric relationships on a hard metal tip according to the invention in the circumferential direction of the round shank chisel effective as torque proportion of acting perpendicular to the guide surfaces compressive force at pitch angles of the guide surfaces between about 30 and about 60 degrees of angle about 50 percent of the resistance of the material to be removed. In this way, a "forced rotation" of the hard metal tip or the chisel is thus achieved according to the invention, which is independent of an inclination of the axis of rotation of the bit or the carbide tip relative to the peripheral plane of the milling drum.

Since its rotation is independent of an inclination of its longitudinal axis relative to a circumferential surface of the milling drum, the hard metal tip according to the invention allows use on milling drums which do not provide this inclination. Without a position of the hard metal tip or the longitudinal axis of the bit relative to a plane perpendicular to the roll axis of rotation, the movement of the bit or the hard metal tip is parallel to the latter Turning or its central axis, so that the splitting process is optimal. The required drive power of the milling machine can therefore be significantly reduced in comparison with known devices and the fuel consumption can be correspondingly greatly reduced with the same performance. The use of the hard metal tip according to the invention therefore enables a particularly economical milling operation, on the one hand because of the greatly reduced by the "forced rotation" of the bit wear and on the other hand due to the reduced energy costs.

Preferably, the guide surfaces on a hard metal tip according to the invention have a pitch angle of about 50 degrees. This allows a good powder metallurgy formability of the hard metal tip according to the invention.

In a preferred embodiment, a hard metal tip according to the invention has twelve guide surfaces arranged on its circumference. The hard metal tip according to the invention then has in each rotated about its longitudinal axis position good contact of the guide surfaces with the material to be removed.

Furthermore, it is advantageous if each guide surface of a hard metal tip according to the invention is formed on a respective web with an essentially constant cross section starting from the tip to the foot region. These webs of a Hartinetallspitze invention then use in their use substantially evenly and ensure a consistent effect on the rotational properties of the round shank chisel.

On the other hand, it is also advantageous to form each guide surface of a hard metal tip according to the invention on a respective hump-like projection whose cross-section, starting from the tip to the foot region, increases substantially conically. The powder metallurgical production is so much easier.

Furthermore, such a projection on a hard metal tip according to the invention can be designed mirror-symmetrically with respect to a plane through the longitudinal axis. The carbide tip according to the invention can then be used equally on two areas of a milling drum, if the round shank chisel in these areas are used inclined in opposite directions relative to a peripheral surface of the milling drum. Alternatively For example, different carbide tips according to the invention can be used in such areas, which differ in opposite inclinations of the respective thread-like spiraling in order to achieve the same rotational behavior of the round-shank bits in both areas of such a milling drum.

The body of a hard metal tip according to the invention preferably has a cone angle of about 30 degrees of angle with respect to the longitudinal axis. The hard metal tip according to the invention thus has a particularly good wear behavior.

In a preferred Ausfühnmgsform the body of the hard metal tip according to the invention is made separately as a ring element and brazed to a cylindrical neck of a hard metal pin. Thus, in modular design, different tips can be combined with the same ring element to carbide tips for different applications.

Based on the known round shank chisels, a round shank chisel is furthermore proposed, which has a carbide tip hard-soldered according to the invention with a base body. Such a round shank chisel has the advantages described above.

embodiment

Fig. 1

eine erste erfindungsgemäße Hartmetallspitze,

Fig. 2a

eine zweite erfindungsgemäße Hartmetallspitze und

Fig. 2b

ein entsprechendes Ringelement,

Fig. 3a

eine dritte erfindungsgemäße Hartmetallspitze und

Fig. 3b

ein entsprechendes Ringelement,

Fig. 4

einen erfindungsgemäßen Rundschaftmeißel,

Fig. 5a + 5b

Seitenansichten einer weiteren erfindungsgemäßen Hartmetallspitze,

Fig. 5c

eine Draufsicht auf die Hartmetallspitze gemäß den Figuren 5a, 5b,

Fig. 5d

einen Schnitt durch die Hartmetallspitze gemäß den Figuren 5a bis 5c sowie durch einen damit verbundenen Meißelschaft,

Fig. 5e

einen gegenüber Figur 5d um 90° gedrehten Schnitt, jedoch ohne den Meißelschaft,

Fig. 5f

eine Unteransicht der Hartmetallspitze gemäß den Figuren 5a bis 5e und

Fig. 5g

eine perspektivische Ansicht der Hartmetallspitze gemäß den Figuren 5a bis 5f von unten.

The invention will be explained below with reference to exemplary embodiments. Show it

Fig. 1

a first hard metal tip according to the invention,

Fig. 2a

a second hard metal tip according to the invention and

Fig. 2b

a corresponding ring element,

Fig. 3a

a third inventive hard metal tip and

Fig. 3b

a corresponding ring element,

Fig. 4

a round shank bit according to the invention,

Fig. 5a + 5b

Side views of another carbide tip according to the invention,

Fig. 5c

a top view of the hard metal tip according to the FIGS. 5a, 5b .

Fig. 5d

a section through the carbide tip according to the FIGS. 5a to 5c and by an associated chisel shaft,

Fig. 5e

one opposite FIG. 5d rotated by 90 °, but without the chisel,

Fig. 5f

a bottom view of the hard metal tip according to the FIGS. 5a to 5e and

Fig. 5g

a perspective view of the hard metal tip according to the FIGS. 5a to 5f from underneath.

In the FIG. 1 shown, powder-metallurgically produced carbide tip 1 according to the invention for a round shank chisel not shown is formed along its longitudinal axis 2, starting from a tip 3 via a body 4 to a foot portion 5 is substantially conical, so along this longitudinal axis 2 has a substantially continuously increasing cross-section. The hard metal tip 1 is further formed radially symmetrical about the longitudinal axis 2 (also: rotationally symmetrical): a rotation of the hard metal tip 1 about the longitudinal axis 2 by an angle of 60 degrees brings them again with itself to cover. The body 4 is conical and has a cone angle, ie an angle of the lateral surface 6 to the longitudinal axis 2 of 33.21 angle degree.

The hard metal tip 1 has six, relative to the body 4 raised, substantially planar guide surfaces 7, which are of the tip 3 to the foot portion 5 substantially parallel to each other helically wound around the longitudinal axis 2. The term parallelism is to be understood in the present context, as in threads, as sectional parallelism of adjacent guide surfaces 7 or their imaginary continuations. The guide surfaces 7 are inclined relative to the longitudinal axis 2 by about 45 degrees and each formed on a web 8 with starting from the top 3 to the foot region 5 substantially constant cross-section.

The second hard metal tip 9 according to the invention FIG. 2a differs from the first hard metal tip 1 according to FIG. 1 on the body 11 six identical hump-like projections 12 are formed, which also each have a mirror symmetry with respect to a plane, not shown by the longitudinal axis 13. The total of twelve guide surfaces 10 are formed on these projections 12 and have an inclination relative to the longitudinal axis 13 of 37.5 angle degree. The projections 12 have a height 14 of 4.4 mm in the direction of the longitudinal axis 13 and a width 15 of 4.8 mm in the circumferential direction of the hard metal tip 9. The hard metal tip 9 in total has a height 16 of 17.2 mm and a diameter 17 of 18.68 mm, in the foot region 18 has a diameter 19 of 15.8 mm.

This in FIG. 2b shown separately manufactured by powder metallurgy ring member 20 has substantially the same concept as the second hard metal tip 9 according to FIG. 2a , The body 21 has a cone angle of 30 angular degrees, a height 22 of 4.6 mm in the direction of the longitudinal axis 23 and without the projections 24 has an outer diameter 25 of 20 mm. The second hard metal tip 9 according to FIG. 2a and the ring member 20 according to FIG. 2b are not suitable for use with respect to a circumferential plane of a milling drum inclined longitudinal axis 23 due to the symmetrical projections 24.

The third hard metal tip 26 according to the invention FIG. 3a again differs from the second hard metal tip 9 according to FIG. 2a It essentially has six guide surfaces 27 formed on the projections 29 with an inclination relative to the longitudinal axis 30 of 45 degrees of angle. In contrast to the second hard metal tip 9, the latter is also suitable for use with inclined, as with a parallel to the circumferential plane longitudinal axis 30.

This in FIG. 3b shown separately manufactured by powder metallurgy second annular element 31 has corresponding to how the first ring member 20 according to FIG. 2b substantially the same concept as the third hard metal tip 26 according to FIG FIG. 3a ,

FIG. 4 shows a Rundschaftmeißel 32 according to the invention, which has a brazed to a base body 33 fourth inventive carbide tip 34. The hard metal tip 34 in turn consists of a cylindrical hard metal pin 35 with 12 mm diameter 36, which is brazed to a separately manufactured as a third ring member 37 body 38 to a not shown separately conical approach.

The third ring element 37 has on its circumference ten identical, slightly curved webs 39, each with a guide surface 40. The webs 39 are inclined by 27 degrees of angle relative to the longitudinal axis 41 of the round shank chisel 32. The ring element 37 has an outer diameter 42 of 19.6 mm and a height 43 of 5.2 mm. The ring member 37 has an inner diameter 44 of 13 mm and - as well known from the prior art - depending on the application with carbide pins of 8 or 10 mm to a round shank bit 32 can be combined.

The in the FIGS. 5a to 5g shown carbide tip 45 is similar in geometry of its integrally formed ring member 46 of the embodiment according to FIG. 4 , The guide surfaces 40 are here again inclined at an angle α = 27 ° to the longitudinal axis 47.

In a lower base surface 48 of the hard metal tip 45 a trapezoidal cross-section annular groove 49 is formed in the powder metallurgical production. In a central region on an underside 59 of the carbide tip 45 thus remains a near-frustoconical extension 50, the top surface 51 is located with the base surface 48 in a plane. As it turned out FIG. 5g can be seen, the extension 50 has two parallel to the longitudinal axis 47 extending flat surfaces 52, which is to cause a Lotabfluss from the gap region on the surface of the extension 50 when soldering the carbide tip 45 with an upper end 52 of a drill collar 53.

Out FIG. 5d it can be seen that an end face 54 of the drill collar 53 is provided with a blind bore 55 into which the extension 50 of the hard metal tip 45 is inserted. The end of the chisel shaft 53 is also provided with a circumferential chamfer 56 on which a corresponding conical lateral surface 57 is supported as a wall of the trapezoidal annular groove 49. The solder joint between the carbide tip 45 and the Chisel shaft 53 thus extends over the walls and the bottom of the annular groove 49 to a gap between the top surface 51 of the extension 50 and the bottom 57 of the blind bore 55. In the top surface 51 of the extension 50 is still a partially dome-shaped recess 58 is formed, which also can serve to accommodate unnecessary solder.

The inventive positive connection between the bottom 59 of the carbide tip 45 and the end face 54 of the cutter shank 53, the durability of the solder joint between the two aforementioned parts is substantially increased. Both facing ends of carbide tip 50 and chisel shank 53 engage in the field of solder seam quasi in a matrix and patrizenartig each other. By the recess on the underside 59 of the carbide tip 45 in the form of the annular groove 49, a portion of the comparatively expensive carbide material is also saved and replaced by the blind bore 55 surrounding ring collar of the existing of a cheaper steel material chisel shaft 53.

1

Hartmetallspitze

2

Längsachse

3

Spitze

4

Korpus

5

Fußbereich

6

Mantelfläche

7

Leitfläche

8

Steg

9

Hartmetallspitze

10

Leitfläche

11

Korpus

12

Vorsprung

13

Längsachse

14

Höhe

15

Breite

16

Höhe

17

Durchmesser

18

Fußbereich

19

Durchmesser

20

Ringelement

21

Korpus

22

Höhe

23

Längsachse

24

Vorsprung

25

Durchmesser

26

Hartmetallspitze

27

Leitfläche

28

Korpus

29

Vorsprung

30

Längsachse

31

Ringelement

32

Rundschaftmeißel.

33

Grundkörper

34

Hartmetallspitze

35

Hartmetallstift

36

Durchmesser

37

Ringelement

38

Korpus

39

Steg

40

Leitfläche

41

Längsachse

42

Durchmesser

43

Höhe

44

Durchmesser

45

Hartmetallspitze

46

Ringelement

47

Längsachse

48

Basisfläche

49

Ringnut

50

Fortsatz

51

Deckfläche

52

Ende

53

Meißelschaft

54

Stirnfläche

55

Sackbohrung

56

Fase

57

Grund

58

Vertiefung

59

Unterseite

In the figures are

1

Carbide tip

2

longitudinal axis

3

top

4

corpus

5

footer

6

lateral surface

7

baffle

8th

web

9

Carbide tip

10

baffle

11

corpus

12

head Start

13

longitudinal axis

14

height

15

width

16

height

17

diameter

18

footer

19

diameter

20

ring element

21

corpus

22

height

23

longitudinal axis

24

head Start

25

diameter

26

Carbide tip

27

baffle

28

corpus

29

head Start

30

longitudinal axis

31

ring element

32

Attack cutting tools.

33

body

34

Carbide tip

35

Hard metal pin

36

diameter

37

ring element

38

corpus

39

web

40

baffle

41

longitudinal axis

42

diameter

43

height

44

diameter

45

Carbide tip

46

ring element

47

longitudinal axis

48

footprint

49

ring groove

50

extension

51

cover surface

52

The End

53

drill collar

54

face

55

blind hole

56

chamfer

57

reason

58

deepening

59

bottom

Claims (9)

Carbide tip (1, 9, 26, 34) for a round shank chisel (32), which is held by a chisel holder on a rotatable roller of a milling machine, wherein the hard metal tip (1, 9, 26, 34), starting from a tip (3) via a body (4, 11, 21, 28, 38) to a foot portion (5,18) is substantially conical and about a longitudinal axis (2, 13, 23, 30, 41) of the round shank chisel (32) formed radially symmetrical and wherein the Carcass (4, 11, 21, 28, 38) from the top (3) to the foot region (5, 18) substantially mutually parallel extending raised guide surfaces (7, 10, 27, 40), characterized in that the guide surfaces (7, 10, 27, 40) are helically wound about the longitudinal axis (2,13,23,30,41). Hard metal tip (1, 9, 26, 34) according to the preceding claim, characterized by a pitch angle of the guide surfaces (7, 10, 27, 40) of about 50 angular degrees. Hard metal tip (9) according to one of the preceding claims, characterized by twelve guide surfaces (10). Carbide tip (1, 34) according to any one of the preceding claims, characterized in that each guide surfaces (7, 40) on a respective web (8, 39) with starting from the top (3) to the foot region (5) substantially constant cross-section is trained. A hard metal tip (9, 26) according to any one of claims 1 to 3, characterized in that each guide surface (10) is formed on a respective hump-like projection (12, 24, 29,) whose cross-section, starting from the tip (3) the foot area is substantially conically enlarged. Hard metal tip (9) according to the preceding claim, characterized in that the projection with respect to a plane through the longitudinal axis (13) is mirror-symmetrical. Hard metal tip (1,9,26,34) according to one of the preceding claims, characterized in that the body (4, 11, 21, 28, 38) with respect to the longitudinal axis (2, 13, 23, 30, 41) has a cone angle of about 30 angular degrees. Carbide tip (34) according to any one of the preceding claims, characterized in that the body (4, 11, 21, 28, 38) as a ring member (20, 31, 37) is manufactured separately and brazed with a cylindrical neck of a hard metal pin 35. Round shank bit (32), characterized by a carbide tip (1, 9, 26, 34) brazed to a base body (33) according to one of the preceding claims.

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