Patent Application
20150075346
This application claims priority to co-pending German Patent Application No. DE 10 2013 110 120.8 entitled “Sägeband mit profiliertem Bandrücken”, filed Sep. 13, 2013.
The present invention generally relates to a saw band including a tooth supporting body and a plurality of teeth being arranged at the tooth supporting body. Opposite to the teeth, the saw band includes a back having a profiled back portion.
The back of the band thus does not extend in the usual straight direction of movement of the band, but it is designed to be profiled, and it includes a plurality of portions extending at different angles with respect to the usual straight direction of movement of the band.
Saw bands having a straight and non-profiled back extending in the usual straight direction of movement of the band are generally known in the art. Such a design results in a uniform feed rate, always the same feed direction and constant cutting forces. Cold work hardened zones are produced in the material of the workpiece to be cut during sawing. Such zones cannot be undercut with such a known saw band. Many teeth are always in full contact in the sense of cutting. In this way, there are great cutting forces, great wear and tear and thus a decreased lifetime of the saw band.
A saw band including a tooth supporting body and a plurality of teeth being arranged at the tooth supporting body is known from German Patent No. DE 697 17 699 T2 corresponding to U.S. Pat. No. 6,532,852 B1. The back of the band opposite to the teeth includes a profiled back having different portions. According to most of the embodiments shown in this document, the profiled back is designed to be wave-like such that a plurality of curved surfaces are located one next to the other. As it is to be seen in
A separate embodiment according to
Different embodiments of saw bands including a tooth supporting body and a plurality of teeth being arranged at the tooth supporting body are known from international patent application WO 2006/019129 A1 corresponding to US patent application No. US 2008/0121079 A1. A back having a profiled back portion is arranged opposite to the teeth. Different embodiments of the profiled band back of different embodiments of the saw band are especially illustrated in
A saw band including a tooth supporting body and a plurality of teeth being arranged at the tooth supporting body is known from French Patent Application No. FR 2 369 048 A1. Opposite to the teeth, the saw band includes a back having a profiled back portion. The profiled back includes a declination portion, which is directly followed by an inclination portion, which is directly followed by a declination portion.
The present invention relates to a saw band including a tooth supporting body, a plurality of teeth being located at the tooth supporting body and a back being located opposite to the teeth. The back includes a profiled back portion. The profiled back portion includes an inclination portion, a declination portion and a compensation portion. The inclination portion has a first length, a first end and a first angle of inclination. The inclination portion is designed and arranged such that a distance of the back to the teeth increases in the inclination portion in a direction towards the first end of the inclination portion. The declination portion has a second length, a second end and a second angle of declination. The declination portion is designed and arranged such that a distance of the back to the teeth decreases in the declination portion in a direction towards the second end of the declination portion. The compensation portion has a third length and a third end. The compensation portion is designed not to be profiled and to be straight such that a distance of the back to the teeth is constant in the compensation portion. The declination portion is located next to the first end of the inclination portion and the compensation portion is located next to the second end of the declination portion. Alternatively, the inclination portion is located next to the second end of the declination portion and the compensation portion is located next to the first end of the inclination portion, the third length of the compensation portion being shorter than first length of the inclination portion and the second length of the declination portion.
The back of the saw band is profiled in a special way to impart different directions of movement other than the usual direction of movement of the band during sawing. The saw band is thus tilted alternatingly clockwise and counterclockwise. This movement results from contact to the guiding elements of the saw machine to the non-straight profiled portion of the back of the saw band.
Due to this tilting movement, there is a discontinuous feed and an aggressive cutting behavior of the saw band. A cold work hardened zone can be produced in the material to be cut due to the cutting pressure. Due to the aggressive cutting behavior, this cold work hardened zone is undercut. The novel profiled portion of the back of the band results in varying cutting forces. The average cutting forces can however be substantially lower compared to a saw band having a straight back. In this way, wear and tear is reduced. Due to the tilting movement, the active length of the saw band is reduced, meaning that less teeth are simultaneously in contact with the material to be cut, the cutting channel is shortened and the cutting forces are reduced. In this way, one attains a good surface quality with reduced roughness values and good straightness of the cut workpiece.
The inclination portion and the declination portion serve to tilt the saw band in opposite directions and are thus also designated as tilting portions. The compensation portion alone would not cause such a tilting movement. However, it is designed and arranged such that it is not active alone and not with another compensation portion, respectively, but only in combination with the inclination portion or the declination portion. This means that one of the guiding elements of the band saw machine contacts the compensation portion and another guiding element simultaneously contacts the inclination portion or the declination portion. In this way, there is the tilting movement of the respective tilting portion—i.e. the inclination portion or the declination portion. The compensation portion decouples the inclination portion and the declination portion from one another. In this way, the tilting movement slows down towards its ending. The transition between the inclination portion and the declination portion is less abrupt due to the intermediate arrangement of the compensation portion such that there is no abrupt increase of cutting forces and the load acting upon the teeth is thus reduced.
The compensation portion increases the effect of the tilting movement of the saw band without having to reduce the height difference between the highest point of the inclination portion and the lowest point of the declination portion. The risk of breakage of the band is reduced due to the decreased weakening of the saw band.
The compensation portion or decoupling portion may be designed as a lowered portion—i.e. a portion being located closer to the teeth of the saw band. However, it can alternatively be a raised portion. Only one of these two portions is arranged—i.e. the lowered compensation portion or the raised compensation portion. In this way, it is ensured that always one tilting portion is effective—i.e. it is in contact with a guiding element of the saw machine—such that the desired tilting movement is realized. In case two non-tiling portions were simultaneously active, there was no continued tilting movement.
In a preferred exemplary embodiment, the profiled back portion includes exactly these three above described portions—i.e. only the inclination portion, the declination portion and the compensation portion. The portions are arranged in the order “inclination portion-declination portion-compensation portion” or “inclination portion-compensation portion-declination portion” in a way that these portions are located directly adjacent to one another. The next profiled back portion including the same portions is then located next to this portion.
The compensation portion if preferably designed to be straight. However, it can also be designed as a curved surface having a huge radius. The inclination portion and the declination portion are also preferably designed to be straight, but they can also be designed as curved surfaces having a huge radius. These portions are located substantially directly adjacent to one another. However, it is also possible that a short straight portion or a short curved portion having a comparatively great radius is arranged in between.
The compensation portion may have a length of more than approximately 30 mm. In this way, it is ensured that the compensation portion can fulfill its buffer function between the inclination portion and the declination portion in case of usual guiding elements of band saw machines. A usual diameter of a guiding element being designed as a single roller is approximately 30 mm. A usual guiding element being designed as a double roller has a width of the roller unit being formed by this double roller of approximately 70 mm.
The length of the compensation portion may be especially more than approximately 50, 60, 80 or 100 mm. The length is especially shorter than approximately 150 mm and especially shorter than approximately 120 mm. The length may be between approximately 60 and 100 mm or between approximately 70 to 90 mm, especially approximately 80 mm.
The inclination portion may have an inclination angle having a different absolute value than the declination portion. In this way, the tilted direction of movement of the saw band compared to the usual direction of movement of the band is attained when the inclination portion and the declination portion simultaneously contact the respective guiding element of the band saw machine. This design is also designated as non-symmetric profiling. However, it is also possible to realize symmetric profiling in which the inclination portion and the declination portion have inclination angles (and declination angles, respectively) having the same absolute value.
The inclination portion and the declination portion may each be arranged at an angle with respect to the horizontal line (which corresponds to the usual straight direction of movement of the band) the absolute value of which is less than approximately 2°. The angle may be especially between approximately 0.1° and 1.0°. In case of non-symmetric profiling, the difference between these absolute values of the two angles is between approximately 0.2° and 0.9°. The inclination portion may have an angle of approximately 1.0° or less. The declination portion then has an angle of approximately 0.5° or less. This design ensures that the desired tilting movement is realized, on the one hand, and the transition between the compensation portion and the respective tilting portion is not too abrupt and thus does not lead to abrupt loads during sawing, on the other hand.
The declination portion may have a length being at least twice as long as the length of the inclination portion. Correspondingly, it has an angle of declination the absolute value of which is smaller than the one of the inclination portion. In this way, non-symmetric profiling of the profiled back portion can be realized well.
The saw band may include an integer plurality of profiled back portions. In this way, during circulation of the saw band through the band saw machine, one attains a uniform total movement including the partial movements being defined by the profiled back portion. The profiled back portions are dimensioned in a way that their integer arrangement along the length of the saw band is possible. The length of the profiled back portions is varied to adapt to the respective length of the band. This length of the band preferably is an integer multiple of the length of the profiled back portion. If all profiled back portions have the same design, this is designated as a fixed division.
However, it is also possible to use a variable division in which the saw band includes at least two profiled back portions having different lengths. This variable division may be realized in different ways. It is especially attained by the length of the respective longer tilting portion—i.e. the inclination portion or the declination portion—being enlarged and being shortened, respectively.
The profiled back portion may be produced such that the machining grooves resulting therefrom extend in a longitudinal direction of the saw band. This means that they extend parallel to the usual non-tilted direction of movement of the band. In this way, the danger of band breakage is substantially reduced. The profiled back portion may be produced especially by milling or grinding.
The transitions between the different portions of the profiled back portion may be formed by comparatively great radii—especially radii of approximately 50 mm or more-to reduce the notch effect, to attain a smoother movement of the saw band and to improve the continuous operation properties. In this way, noise emission during sawing is substantially reduced.
The tooth supporting body at its side facing away from the teeth may be designed not to be profiled apart from the teeth. In other words, the tooth side is especially designed not to be profiled, but it has the basic shape of a usual straight design.
The teeth may be arranged in a group of teeth being repeated along the tooth supporting body. The group may include the following teeth: a surface tooth C3 having the greatest width and the smallest height in the group and two performance teeth C1, C2 having greater heights and smaller widths than the surface tooth C3.
The performance tooth C1 having the greatest height and the smallest width may be arranged more than once in the group and/or the surface tooth C3 may be arranged more than once in the group. Especially, the group may include the performance tooth C1 twice, the surface tooth C3 twice and the performance tooth C2 only once, especially in the order C1-C3-C1-C2-C3. This special design is adapted to the novel design of the profiled back portion.
If a group of teeth known from the prior art is used in the novel saw band having the novel profiled back portion, it has been found that the teeth C1 and C3 participate in chipping in an increased way and thus wear out in a respectively shorter period of time. In contrast, the tooth C2 participates less in chipping. The above described novel arrangement of five teeth now allows to arrange the teeth C1 and C3 more frequently such that wear and tear is substantially reduced and the lifetime of the saw band is significantly increased.
At least a part of the teeth may have a rake angle of approximately 10° or more, especially approximately 12° or more and a clearance angle of approximately 18° or more, especially approximately 20° or more. In this way, the cutting wedge is designed to be thinner and to be thus more aggressive. In this way, the cutting forces are reduced and cold work hardening of the material of the workpiece to be sawed is counteracted. Due to the increased rake angle, less chip deforming work has to be performed. Due to the increased clearance angle, frictional forces in the chipping process are reduced.
The tooth supporting body and the base of the teeth are preferably made of metal, especially tempered steel. The cutting edge and at least a further part of the tips of the teeth is also made of metal, especially alloyed tool steel and high-speed steel, respectively, or abrasive cutting materials such as carbides, cermet, ceramic cutting materials or diamond. This material is harder than the material of the tooth supporting body such that the saw band is especially suitable for sawing metals. The teeth can also include a hard coating serving to increase resistance against wear and tear. However, it is also possible to cut other materials—especially wood or plastics—with the saw band.
Advantageous developments of the invention result from the claims, the description and the drawings. The advantages of features and of combinations of a plurality of features mentioned at the beginning of the description only serve as examples and may be used alternatively or cumulatively without the necessity of embodiments according to the invention having to obtain these advantages. Without changing the scope of protection as defined by the enclosed claims, the following applies with respect to the disclosure of the original application and the patent: further features may be taken from the drawings, in particular from the illustrated designs and the dimensions of a plurality of components with respect to one another as well as from their relative arrangement and their operative connection. The combination of features of different embodiments of the invention or of features of different claims independent of the chosen references of the claims is also possible, and it is motivated herewith. This also relates to features which are illustrated in separate drawings, or which are mentioned when describing them. These features may also be combined with features of different claims. Furthermore, it is possible that further embodiments of the invention do not have the features mentioned in the claims.
The number of the features mentioned in the claims and in the description is to be understood to cover this exact number and a greater number than the mentioned number without having to explicitly use the adverb “at least”. For example, if a profiled back portion is mentioned, this is to be understood such that there is exactly one profiled back portion, two profiled back portions or more profiled back portions. Additional features may be added to these features, or these features may be the only features of the respective product.
In the following, the invention is further explained and described with reference to preferred exemplary embodiments illustrated in the drawings.
The views are true to scale such that the geometric relations between the single elements of the saw band can be determined from the drawings. This also applies with one restriction to the profiled back portion illustrated in
The profiled back portion 5 includes an inclination portion 6. The back portion 4 is designed to be profiled in the inclination portion 6 such that its distance to the teeth 3 increases. The profiled back portion 5 furthermore includes a declination portion 7 being located next to the upper end 9 of the inclination portion 6. The back 4 is designed to be profiled in the declination portion 7 such that its distance to the teeth 3 decreases. A compensation portion 8 is then located next to the lower end 10 of the declination portion 7. The back 4 is designed to non-profiled and to be straight in the compensation portion 8 such that its distance to the teeth 3 is constant.
The compensation portion 8 up to its end 11 extends in the direction corresponding to the usual straight direction of movement of a saw band having a straight back. In contrast, the inclination portion 6 is arranged to be inclined at an inclination angle βinclination with respect to the usual direction of movement of the band. The declination portion 7 is arranged to be declined at an angle βinclination with respect to the usual direction of movement of the band. Due to the above described partial enlargement of the illustration of the drawing, these angles are actually substantially smaller.
The exemplary embodiment illustrated in
The following table lists the respective values of this exemplary embodiment:
The following table lists the respective values of this exemplary embodiment:
The saw machine includes guiding elements 12. In this case, each guiding element 12 is designed as a single roller 13. The back 4 and thus the saw band 1 is guided by these guiding elements 12 in the region of the workpiece to be cut (not illustrated). The workpiece to be cut is located between the guiding elements 12. In the illustration of
The non-straight direction of movement of the saw band 1 results from the contact of the profiled back 4 to the guiding elements 12.
In the position illustrated in
This tilted position is generally maintained, but it is weakened until the position illustrated in
When this movement of the saw band 1 is continued, one attains a position tilted in a clockwise direction, the maximum of which is shown in
When this movement of the saw band 1 is continued, this tilted position is generally maintained, but it is weakened as this is shown in
The cycle is then completed by a continued movement of the saw band 1, and the position illustrated in
In the position illustrated in
During continued movement of the saw band 1 towards the right, the saw band 1 is then tilted in a counterclockwise direction. The maximum tilted position is illustrated in
During continued movement of the saw band 1 towards the right, the tilted position in a counterclockwise direction is further reduced until the balanced position is reached, as it is illustrated in
During continued movement of the saw band 1, one then attains a tilted position in a clockwise direction. The maximum tilted position is illustrated in
During continued movement of the saw band 1 towards the right, the tilted position is reduced such that e.g. the position illustrated in
During continued movement of the saw band 1, the cycle is completed and the position illustrated in
In another exemplary embodiment of the novel saw band 1 not being illustrated, the asymmetrical profiled back portion 5 has a different total length and the inclination portion 6 and the declination portion 7 each have a different length. Other designs are possible to adapt to the length of the band.
The following table lists the respective values of this exemplary embodiment:
The saw band 1 illustrated in
The saw band 1 illustrated in
The group of teeth includes a performance tooth C1 having the greatest height and the smallest width. This performance tooth C1 is arranged twice in the group. The performance tooth C1 that is arranged further in the back as seen in the projection cannot be seen in the illustration since it is covered by the performance tooth C1 being located further in the front. The surface tooth C3 is located behind the front performance tooth C1. This surface tooth C3 has the greatest width and the smallest height in the group. The next tooth is the further performance tooth C1. The next tooth is another performance tooth C2 having the second greatest height and the second greatest width of the teeth 3. The next tooth is another surface tooth C3 being located twice in the group. The surface tooth C3 being located further in the rear as seen in the projection cannot be seen in the illustration since it is covered by the surface tooth C3 being located further in the front. Thus, the order of teeth is C1-C3-C1-C2-C3. This series of teeth is then repeated along the length of the saw band 1.
As it is to be further seen in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2013 110 120.8 | Sep 2013 | DE | national |
