EP3713672A1

EP3713672A1 - Beater arm

Info

Publication number: EP3713672A1
Application number: EP17816661.7A
Authority: EP
Inventors: Frederik HOOGENDOORN
Original assignee: Keestrack NV
Current assignee: Keestrack NV
Priority date: 2017-11-23
Filing date: 2017-12-08
Publication date: 2020-09-30
Anticipated expiration: 2037-12-08
Also published as: AU2017440800A1; NZ763156A; CN111263664A; ES2950505T3; US20200306763A1; CN111263664B; CA3074527C; PL3713672T3; EP3713672C0; DE202017107107U1; CA3074527A1; US11446674B2; AU2017440800B2; EP3713672B1; WO2019101351A1

Abstract

The invention relates to a beater arm for use in an axially parallel beater arm holder (7) of a rotor (1) of an impact crusher, comprising the following features: a) the beater arm (6) has a longitudinal axis running in the Z-direction within a Cartesian coordinates system, which runs parallel to the beater arm holder (7) in the installation position, a vertical axis running in the Y-direction, which is directed towards a radially outer top surface (8) of the beater arm (6), and a transverse axis running in the X-direction, which is directed towards a longitudinal side of the beater arm (6); b) the beater arm (6) is designed to be rotationally symmetrical in relation to the longitudinal axis; c) the beater arm (6) has a respective head (11) - with a rectangular cross-section - at the upper and lower ends in the vertical direction thereof, wherein each head (11) has lateral surfaces (9, 10) on the longitudinal side, which each run parallel at a first distance (A1) to one another, such that the head has a thickness (D1) between the lateral surfaces (9, 10); d) there is a central region (12) between the two heads (11) in which the longitudinal axis centrally determines the position of a Y-Z plane; e) the lateral surfaces (9, 10) run parallel to the Y-Z plane, wherein, in the transverse direction, the two heads (11) are arranged offset to the Y-Z plane by a second distance (A2) in the opposite direction, such that support shoulders (22) are arranged in the transition to the central region (12); f) the central region (12) has a thickness (D2) over the majority portion of its length that is not smaller than the first distance (A1) of the lateral surfaces (9, 10) of the heads (11).

Description

Schlaqleiste

The invention relates to a blow bar for an impact crusher with the features of claim 1.

Impact crushers are used for crushing mineral materials (natural stone or recycled material) and for producing fine or coarse aggregate. In this case, the material is brought in free fall in the range of impact bars of a rotor and thrown from there against baffles. There it breaks. The blow bars are wearing parts and must be replaced regularly. Blow bars usually have two impact areas, ie heads, which are used successively when one of the heads has reached the wear limit. Then the blow bars can be turned around their own longitudinal axis. A not yet worn head of the blow bars, which was in a blow bar recording in the rotor, passes thus to the outside, so that the blow bar can be used to reach the wear limit of this head. It is desirable in terms of the degree of utilization of the material used when the central region of the blow bars is as small as possible and the head exposed to wear is as large as possible. However, if the mid-range is too small, it can lead to high voltages in the blow bar. The blow bar can break, which can cause damage to other parts of the impact crusher. Repairs and production losses are the result. If the center area is too large, significant parts of the material of the blow bar can not be used for contact with the material to be shredded. A low degree of utilization is economically unfavorable. However, if the mid-range is too weak, premature failure can occur if the blow bar breaks.

The invention has for its object to show a blow bar for an impact crusher, which has a long service life and a high degree of utilization.

The object is achieved with a blow bar with the features of claim 1.

The subclaims relate to advantageous developments of the invention.

It is proposed a reversible blow bar for insertion into an axially parallel blow bar recording a rotor of an impact crusher. A maximum degree of utilization of the blow bar results when the blow bar can be turned after the wear of one end of the blow bar. The blow bar has in the middle of a central area and adjacent to the central area each have a striking area, which is also referred to as a head. One of the two heads at the ends of the list is in each case in an insert position, that is, he protrudes from the rotor. The other head is meanwhile protected in a rotor seat of the rotor and can be brought by turning the blow bar in the use position.

Within a Cartesian coordinate system, the blow bar has a longitudinal axis running in the z-direction, which runs parallel to the impact bar mount of the rotor in the installed position. The blow bar has a y-direction extending vertical axis, which is directed to a radially outer top surface of the blow bar. Finally, the blow bar has a transverse axis running in the x direction, which is directed onto a longitudinal side of the blow bar. The origin of this coordinate system is in the middle of the cross-sectional area of the blow bar.

The blow bar is rotationally symmetrical with respect to its longitudinal axis. It is not mirror-symmetric with respect to the x-z plane and also not with respect to the perpendicular y-z plane. The blow bar has at its upper and lower ends in the vertical direction in each case a rectangular cross-section head. Each head has longitudinal side surfaces, which each extend parallel to each other at a first distance. This first distance between the front and rear side surface defines the thickness of the respective rectangular head. Rectangular means in this context that the side surfaces in the context of manufacturing tolerances parallel to each other and are also parallel to the y-z plane. Nevertheless, the two heads are not arranged in mirror image, but offset in the transverse direction, that is in the x direction, by a second distance in opposite directions. The two heads are shifted in the transverse direction to each other, this results in no mirror symmetry, but a rotational symmetry with respect to the longitudinal axis. The blow bar is bent in each case in the transition to the middle central region. The middle area runs, as it were, diagonally between the two heads. There are in the transition to the central region on each longitudinal side of the blow bar support shoulders, over which centrifugal forces of the blow bar in the impact power absorption can be introduced.

A feature of the invention is that the central region has a thickness which is not less than the thickness of the heads over most of its length. On the "overwhelming part" refers to the vast majority, that is in particular to more than 70% to 90%. For axial extraction of the blow bars from the blow bar recording a receptacle for a holder can be arranged in the end region of the blow bars. In this area there is a constriction, which reduces the cross section in the middle area. This constriction is, however, for the degree of utilization and for operational safety the blow bar irrelevant. Apart from this somewhat thinner designed end portion, the thickness of the central region is not smaller than the thickness in the region of the heads. Moreover, even over its height considered in extrapolation, the mid-range is, for the most part of its height, in particular complete, no smaller than the thickness of the heads. Information on the thickness ratios always refer to the unworn state of the blow bar.

In a further development of the invention, the said central region is even at least 3% thicker than the heads over most of its length. For cast components, such as with such blow bars, manufacturing tolerances of +/- 1% are to be expected. The differences in thickness between the central region and the heads are significantly larger in this embodiment of the invention and are preferably in a range of 2-5%, in particular in a range of 3-4%. As a result, the impact strip according to the invention has a reinforced cross section and has a higher security against breakage in this area.

A further advantageous embodiment of the invention provides a contact surface, which is formed on each side of the blow bar and is arranged in the transition from the central region to the rear side surface. Forces are transmitted from the blow bar in the radial direction into the rotor via the contact surface or the torque of the rotor is transferred to the blow bar via a blow bar holder. The contact surface is raised. By the sublime, i. projecting contact surface is a material allowance available, which allows a surface treatment of the contact surface without a depression in the blow bar is formed. The contact surface is also raised so that there are no constrictions in this area. As a result, notch stresses are avoided. The contact surface is preferably designed only as wide and long as necessary. Therefore, it can also be shorter and narrower than the support shoulder. The contact surface itself runs parallel to the y-z plane.

The raised contact surface is followed by rounded flanks to the rear side surface, wherein the flanks are rounded completely concave. The advantage of this is that the flanks always remain rounded, irrespective of the removal of material on the contact surface, so that the notch stresses occurring under load occur always be kept to a minimum in this area. In the area of the contact surfaces, the highest surface pressures occur between the rotor and the blow bar, wherein the two contact surfaces are exposed to continuous wear. It is therefore important that even after changing a blow bar, the new blow bar has a plane as possible, ie flush surface, in the area of the contact surfaces. The contact surfaces are therefore machined span lifting.

In a first embodiment of the invention, the head terminates in the support shoulder, which is adjoined by the central region. The support shoulder is therefore in front of a rear side surface, but not opposite to the other side surface on the corresponding longitudinal side of the blow bar. In an alternative embodiment of the invention, the support shoulder is also in front of the front side surface. This support shoulder enlarges the contact area between the blow bar holder and the blow bar. The local surface pressure in terms of centrifugal forces is reduced.

In a further development of the invention, in addition, the obtuse angle, by which the support shoulder is inclined relative to the side surfaces, is smaller and in particular less than 117 °. Preferably, it is 115 °. A smaller angle has the advantage that the blow bar receptacle is exposed to lower spreading forces, which are a consequence of the centrifugal forces acting on the blow bar. The blow bar acts like a wedge, which widens the blow bar recording. A smaller angle reduces the wedge effect. Another advantage is that the overall length of the central area is reduced. The proportion of material of the central region in relation to the heads is smaller. The utilization rate is improved.

When the support shoulder protrudes from the front side surface, the support shoulder forms flanks of longitudinal webs raised from the front side surface. The longitudinal webs may be trapezoidal in cross section and have flanks on both sides. The flank angles of the longitudinal webs are preferably identical and are preferably in a range of 110 ° to 117 °. In the transition to the inclined surfaces of the central middle area of the resulting angle is even greater, by the angle of the inclined surfaces, which may be 10 ° to 20 °, so that a total of a gentle, low-voltage transition of the inner edge, ie the support shoulder is created to the central region. In contrast to the above, the first embodiment without longitudinal web, the head ends in the variant with longitudinal web with respect to the thickness ratios according to the invention already at the outer edge of the longitudinal web not only on the support shoulder. The thickness specifications of the head refer in each case to the narrowest area of the head without the longitudinal webs.

As a backup in the axial direction, at least one, in particular two depressions in the front side surface, in particular in a raised longitudinal web can be formed. An axial securing is, for example, a bolt that is guided by a blow bar holder after insertion of the blow bars and connected to the blow bar holder, in particular screwed. Since forces hardly act in the axial direction, a very simple axial securing is sufficient here. The recesses have a depth that extends into a plane that is still above the contact surfaces. They therefore protrude only relatively little into the bar and lead only slightly to a local weakening. This effect is smaller, however, when the depressions are arranged in the raised longitudinal webs. The depressions are preferably arranged directly opposite the contact surfaces, so that there is no reduction in the thickness in this region with respect to the cross section in the x direction.

The inventive design of the blow bars is particularly suitable for blow bars with a thickness of the head of 100 mm and a total height of about 300 mm. It is therefore relatively compact and thick blow bars. The diametrically opposite front side surfaces are located at a distance of about 30-40% of the thickness of the head. Thus, the uncoupled impact afford a total thickness of 130-140% of the thickness of a head. The raised abutment surfaces are raised and about 8-15% compared to the thickness of the head, ie they are at a head in a thickness of 100 mm by about 10 mm before. However, they do not increase the overall thickness of the blow bar. However, the total thickness may increase over the above values if additional raised longitudinal ridges are present. In this case, the longitudinal webs form the furthest protruding areas in the x-direction. They can each have a thickness of 10-15% of the thickness of the heads and with a head with a thickness of 100 mm, for example, have a thickness of 13 mm, so that the blow bar has a total thickness of 148 mm. This corresponds approximately to proportions of 1: 1, 5 (total height: total thickness). Such a compact blow bar is extremely insensitive to breakage in the central area and at the same time has a high degree of utilization.

The invention will be explained in more detail with reference to the embodiments schematically illustrated in the figures. Show it:

Figure 1 shows a rotor of an impact crusher in a plan view;

FIG. 2 shows a section through the rotor of FIG. 1 along the line II-II;

Figure 3 The detail III of Figure 2;

Figure 4 The blow bar of Figure 3 in a first view;

FIG. 5 shows the blow bar of FIG. 4 in a second view;

Figure 6 shows a second embodiment of a blow bar in a view of the

Longitudinal side;

FIG. 7 shows the blow bar of FIG. 6 in a second view;

Figure 8 An axial securing in a first view and

Figure 9 shows the axial securing of Figure 8 in longitudinal section along the line IX-IX.

FIG. 1 shows a rotor 1 of an impact crusher which is otherwise not shown in greater detail. The rotor 1 has a horizontal rotor shaft 2, which is mounted in bearings 3, 4. The rotor shaft 2 extends horizontally between the bearings 3, 4. It is driven by a pulley 5. On the rotor 1, four blow bars 6 are arranged distributed over the circumference. The blow bars 6 extend parallel to the axis of rotation D of the rotor shaft. 2

In the following explanation of the blow bars 6 reference is made to a Cartesian coordinate system (Figures 1 to 4). The origin of the coordinate system is located in the middle of the bar 6, ie halfway Length (z-axis), height (y-axis) and width (thickness) (x-axis) of said beater bar 6. The coordinate system refers to the respective beater bar 6 and not to the rotor 1. Since the beater bar 6 in the Installation position is slightly inclined, and the coordinate system in Figures 2 and 3 is slightly inclined about the longitudinal axis (z-axis) of the blow bar 6.

The x-direction of the coordinate system points toward a surface normal of the front side surface 9. The y-axis is the radial direction and points away from the rotor shaft 2. The z-axis is parallel to the front side surface 9 and to the rotation axis D.

FIG. 2 shows that a total of four blow bars 6 are distributed uniformly on the circumference of the rotor 1. The four blow bars 6 are identical. The rasp bars 7 are in the longitudinal direction of the rotor 1, d. H. parallel to the axis of rotation D of the rotor shaft 2 extending recesses. Based on the above-mentioned coordinate system, the depressions extend in the z-direction.

FIGS. 2 to 4 show that the blow bar 6 is neither related to the horizontal plane, ie H. the x-z plane still relative to the vertical longitudinal plane, d. H. the y-z plane are not mirror-symmetric. However, they are rotationally symmetric with respect to the central longitudinal axis, which runs in the z-direction, because it can be imaged onto itself when rotated by 180 ° about the longitudinal axis.

The blow bars 6 have at their opposite ends respectively radially outer top surfaces 8 (Figures 3 and 4). Since blow bars 6 are cast components, the top surfaces may have a slight draft due to casting technology. The side surfaces 9, 10 of the blow bar 6 extend at a parallel distance from each other and are thus substantially perpendicular to the top surfaces 8 (Figure 3). The blow bar 6 has at its upper and lower ends in the vertical direction in each case a rectangular cross-section head 11, each head 11 has the said front and rear side surfaces 9, 10 which extend parallel to each other at a first distance A1. The distance A1 of the side surfaces 9, 10 is at the same time the thickness D1 of the head 11 in the x direction (FIG. 3). Each head 11 has one over its entire length and height uniform thickness D1, so that the cross section of the head 11 is rectangular. The front side surface 9 serves as a striking surface, which is exposed during operation to a continuous wear.

The blow bar 6 has between the two heads 11 a central region 12 in which centrally the longitudinal axis (z-axis) extends. The side surfaces 9, 10 extend parallel to the y-z plane, wherein the heads 11 are arranged in the transverse direction (x-direction) by a second distance A2 in the opposite direction to the y-z plane. This means that viewed in the vertical direction, the upper head 11 is not completely aligned above the lower head 11. The two heads 11 are offset from each other in the transverse direction, wherein the central region 12, which connects the two heads 11 together, extends obliquely. The blow bar 6 is thereby bent in total. The second distance A2 is 10 to 20%, in particular 15-20% of the thickness D1 of the head 11.

A feature of the invention is that the central region 12 has a thickness D2 over the majority of its length which is at least not smaller than the thickness D1 of the heads 11. While the thickness D1 of the head 11 in the x-direction is measured the thickness D2 of the central region 12 in a measuring direction perpendicular to the inclined central region 12. The thickness D2 of the central region is not smaller than the thickness D1 even in deviating measuring direction. The cross section in the middle central region 12 is not weakened and has no constrictions, which reduce its own thickness D2 compared to the thickness D1 of the heads 11. In this embodiment, the thickness D2 in the central region is the same as the thickness D2 of the head. The safety against breakage in this middle central region 12 is significantly increased.

The blow bar 6 has between the central region 12 and the operating in each case front side surfaces 9 of the heads 12 a respect to the front side surface 9 in the x direction projecting support shoulder 13. The larger the lateral offset of the heads 11, the further the support shoulder 13 projects ,

The support shoulder merges into the front side surface 9. Figure 3 shows how the support shoulder 13 in the installation position serves to the blow bar 6 in the To keep blow bar recording 7. The support shoulder 13 is supported on a rear impact bar holder 15, which is welded into the rotor 1.

Figure 3 shows in dashed line wear lines of the upper head 11. The wear begins at the corner between the front side surface 9 in the transition to the top surface 8. If the wear is too advanced, the blow bar 6 is turned. The sectional view of Figure 3 also shows that within the heads 11 rectangular areas are arranged, which are made of a more wear-resistant material than the surrounding jacket of the blow bar 6. It may be embedding a ceramic material.

At a distance from the support shoulder 13 is located in the transition to the other head 11 of the blow bar 6 a contact surface 16 (Figures 3 and 4). Via the contact surface 16, the force acting in the circumferential direction is transmitted from the rotor 1 to the beater bar 6 or, in the event of an impact of a material to be comminuted, the impact force is transferred from the material into the rotor 1. To avoid stress, it is advantageous if a flush, i. preferably full-surface contact, between the contact surface 16 and the blow bar holder 15 consists. Since blow bars 6 are cast components, thermal distortions can occur during the production process (hardening distortion). A material-saving post-processing is required to create a flat surface. The material-repealing post-processing inevitably leads to a reduction of the cross section of the blow bar, which is undesirable according to the invention, provided that constrictions are formed. Therefore, the contact surface 16 is so far raised with respect to the rear side surface 10 of the head 11 that there is always enough material available for the material-lifting machining without a constriction being formed. In this embodiment, the contact surface projects by the dimension A3, which corresponds to 10% of the thickness D1 of the head 11.

The diametrically opposite second abutment surface 16 serves for support on a front impact strip holder 17. In operation, a high torque is exerted on the impact strip 6 by impacting material about the longitudinal axis. Belonging to the contact surfaces 16 abutment surfaces on the beater bars holders 15, 17 extend in the context of manufacturing tolerances parallel to the side surfaces 9, 10 of the blow bar 6, so that only normal forces on the contact surfaces 16 are transmitted. Centrifugal forces are transmitted via the separate support shoulder. This functional separation is favorable for the power transmission and avoids voltage peaks by superposition of normal forces and bending moments within the blow bar 6.

The beater bars 15, 17 lead and hold the beater bar 6 in the longitudinal direction and in the circumferential direction. A safeguard against axial displacement in the longitudinal direction of the rotor 1 via at least one recess 18 adjacent the support shoulder 13 (Figure 3). The depressions 18 are designed to receive a releasably insertable axial securing device 19 (FIGS. 5 to 7). This axial securing device 19 may, for example, be a securing pin which passes through a bore in the blow bar holder 15 and engages in the depression 18. To fix the position, the at least one axial securing device 19 can be screwed to the blow bar holder 15. For this purpose, the axial securing device 19 has a plate 26 welded to a bolt 20 with a bore 27 for a screw, as FIGS. 8 and 9 show.

Theoretically, only a single recess 18 per longitudinal side may be present. For reasons of safety, however, it is better if two depressions 18 and axial securing means 19 are present, as is also shown in the side view according to FIG. The advantage of multiple axial fuses over a single axial lock is that if the blow bar breaks, the broken off part is also more likely to be held, compared to just one axial lock in which the broken part can not be held.

In the invention occurs in the region of the wells no weakening of the central area 12, because on the other side of the blow bar 6, the contact surface 16 opposite the recess 18 is arranged. In this area, the measured in the x direction thickness of the blow bar 6 is greatest. According to the invention, it is not smaller than the thickness D1 of the heads 11 in this area, even less the depth of the recesses 18th While the abutment surfaces 16 are raised with respect to the rear side surfaces 10, this is not absolutely necessary with the support shoulders 13. The support shoulder 13 should above all absorb the centrifugal forces, which act on the blow bar 6 by the rotational movement. The support shoulder 13 can therefore directly adjoin a front side surface 9.

The support shoulder 13 may additionally protrude in relation to the front side surface 9 according to a second embodiment. In this case, 9 longitudinal webs 14 are arranged on the front side surfaces. Figures 5 and 6 show the differences between a bar 6 with and without the longitudinal webs 14. The bar 6 of Figure 6 is also shown in Figure 7, wherein the same reference numerals are used for Figure 7, as for Figure 5. The difference is only the raised longitudinal ridge 14 on the support shoulder 13. Incidentally, reference is made to the explanations to FIG. 4 for FIG.

Incidentally, FIGS. 5 and 6 show that at the ends of the blow bar 6, openings 21 are arranged in end depressions 25 adjacent to the contact surface 16. In the openings 21 and recesses 25 are used to receive a mounting tool to use the very heavy blow bars 6 in the blow bar recording 7 or to remove it.

The central region 12 of the blow bars 6 is functionally considered that region which does not wear out by contact with the material to be comminuted. The central region 12 includes the functional surfaces over which the blow bar 6 is held. The central region 12 ends at the level of the outer flanks 24 of the abutment surfaces 16. On the opposite side of the central region 12 ends with the end of the recesses 18 or, if present, with the outer edges of the longitudinal webs 14 (Figure 4, Figure 7).

The central region 12 has on both sides inclined surfaces 22, which run parallel to each other. They run at an angle W2 deviating from 90 ° to the yz plane. The angle W2 is determined by the offset of the two heads 11 in the transverse direction and the distance of the heads 11 to each other in the vertical direction. He is less than 180 °. In this embodiment, it is 165 ° (Figure 4). A flank angle W1 of the support shoulder 13 is 115 ° with respect to the rear side surface 10. Opposite the front side surface 9, the flank angle W3 in this example is also 115 °. The inclined surfaces 22 close to the support shoulder 13 in this embodiment, therefore, an angle of 130 °. The steep angle W1 of the support shoulders 13 causes the support shoulders 13 are arranged only at a small parallel distance A4 to each other. The support shoulders are arranged near the center of the blow bar 6. Therefore, the forces are introduced relatively centrally in the reinforced central region 12. The voltage paths are short. The material load is lower.

Between the inclined surface 22 and the support shoulder 13 is a rounded transition 23. The rounding of the transition 23 avoids voltage spikes. The rounding is smaller than at the flanks 24 of the contact surface 16. The transition 23 is in particular fleas of the x-axis.

The contact surfaces 16 are trapezoidal in cross section. Their flanks 24 are rounded with particularly large radii so that there are as few voltage peaks in the transition to the heads 11. The concave rounded edges 24 also have the advantage that regardless of how much material must be removed from the contact surfaces, always a rounded transition to the side surfaces 10 and the inclined surfaces 22 remains.

The embodiment of Figure 7 shows that the longitudinal web 14 is a total of trapezoidal, the flanks 24 of the longitudinal web 14 have the same flank angle as the support shoulder 13 which adjoins the longitudinal web 14. In addition, FIG. 7 shows the total thickness D4 of the blow bar 6.

REFERENCE CHARACTERS:

1 rotor

2 rotor shaft

3 bearings

4 bearings

5 pulley

6 blow bar

7 striker recording

8 head area

9 side surface

10 side surface

11 head

12 mid-range

13 support shoulder

14 longitudinal bar

15 rear baffle holder

16 contact surface

17 front blow bar holder

18 deepening

19 axial securing

20 bolts

21 opening

22 inclined surface

23 transition

24 flank

25 deepening

26 plate

27 bore A1 distance from 9, 10

A2 distance from y-z axis

A3 distance of the contact surface of 10 A4 parallel distance between 13/13 A5 distance from 14 to 9

D rotation axis

D1 thickness of 11

D2 thickness of 12

D4 total thickness

W1 angle

W2 angle

W3 angle

Claims

claims

1. beater bar for insertion into an axis-parallel beater bar receptacle (7) of a rotor (1) of an impact crusher with the following features: a) The beater bar (6) has within a Cartesian coordinate system a longitudinal axis extending in the z-direction parallel to the beater bar receptacle in the installed position (7) extends, a vertical axis extending in the y-direction, which is directed to a radially outer top surface (8) of the blow bar (6) and an x-axis transverse axis, which is directed to a longitudinal side of the blow bar (6); b) The blow bar (6) is rotationally symmetrical with respect to the longitudinal axis formed; c) The beater bar (6) has at its upper and lower ends in the vertical direction in each case a rectangular cross-section head (11), each head (11) has longitudinal side surfaces (9, 10) which in each case at a first distance (A1) parallel to each other so that the head has a thickness (D1) between the side surfaces (9, 10); d) Between the two heads (11) there is a central region (12) in which centrally the longitudinal axis determines the position of a y-z plane; e) The side surfaces (9,10) are parallel to the yz plane, wherein the two heads (11) are arranged in the transverse direction by a second distance (A2) in the opposite direction to the yz plane, so that support shoulders (22) are arranged in the transition to the central region (12); f) The central region (12) has over the majority of its length a thickness (D2) which is not less than the first distance (A1) of the side surfaces (9, 10) of the heads (11).

2. blow bar according to claim 1, characterized in that the

Central region (12) on the majority of its length has a thickness (D2) which is at least 3% greater than the thickness (D1) of the heads (11).

3. blow bar according to claim 1 or 2, characterized in that between the central region (12) and the rear side surfaces (10) of the two heads (11) opposite the rear side surface (10) raised abutment surface (16) is arranged.

4. blow bar according to one of claims 1 to 3, characterized in that adjoin the raised contact surface (16) rounded flanks (24) to the rear side surface (10) and the inclined surface (22), wherein the flanks are rounded completely concave.

5. blow bar according to one of claims 1 to 4, characterized in that between the central region (12) and the front side surfaces (9) arranged in the transverse direction (x-direction) relative to the rear side surface (10) projecting support shoulder (13) is, wherein the support shoulder (13) additionally protrudes with respect to the front side surface (9).

6. blow bar according to claim 5, characterized in that the support shoulders (13) form flanks of longitudinal webs (14), wherein the longitudinal webs relative to the front side surfaces (9) are raised and are trapezoidal in cross-section.

7. blow bar according to one of claims 1 to 6, characterized in that the support shoulders (13) with the respective rear side surface (10) include a flank angle (W1) which is smaller than 117 °.

8. blow bar according to one of claims 5 to 7, characterized in that the support shoulders (13) are longer in the longitudinal direction than the contact surfaces (16).

9. blow bar according to one of claims 5 to 8, characterized in that the longitudinal webs (14) in the y direction wider than the contact surface (16).

10. blow bar according to one of claims 1 to 9, characterized in that in the front side surfaces (9) each have at least one recess (18) for receiving a Axialsicherung (19) is arranged, wherein the recesses (18) opposite the contact surfaces (16 ) are arranged so that the Thickness (D2) of the central region (12) in the region of the depressions (18) is not smaller than the thickness (D1) of the heads (11).

11.Schlagleiste according to one of claims 1 to 10, characterized in that the central region (12) has front and rear inclined surfaces (22), wherein the inclined surfaces (22) in each case from the contact surface (16) to the support shoulder (13) extend and wherein the inclined surfaces (22) are non-parallel to the yz plane.

12. A blow bar according to claim 11, characterized in that rounded transitions (23) from the inclined surfaces (22) to the support shoulders (13) in the x-z plane is arranged.