DE8625500U1 - Saw blade - Google Patents

Description

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Description:

The invention relates to a saw blade, preferably for clamping on one side in a machine tool, such as a jigsaw blade, table saw blade or the like according to the preamble of claim 1.

Saw blades clamped on one side in a machine tool are exposed to high bending and torsional stress. The base material of the saw blades, hereinafter referred to as jigsaw blades, therefore consists of a material with high toughness or high elasticity, i.e. an alloyed tool steel or spring steel.

In order to be able to work on particularly hard materials such as glass fiber reinforced plastics, tiles, ceramics, etc., jigsaw blades with a hard metal grain coating, i.e. jigsaw blades without a geometrically defined cutting edge, have become known. In this case, material is removed by grinding. Saw blades with hard metal coated tooth tips, i.e. with a defined geometric cutting edge for working on particularly hard materials, have also become known. The still known application of hard metal plates to the cutting teeth, as is known for example from DE-OS 33 07 170, is hardly feasible for jigsaw blades with very small teeth, since the application of the hard metal cutting plates and their durability leads to major problems. A jigsaw blade made of solid hard metal is ruled out for cost reasons and in particular because of the poor bending properties of hard metal - great hardness, high brittleness.

From the British patent application GB-A-840 784 a jigsaw blade has become known in which the

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The base body is provided with a narrow hard metal cutting strip. The hard metal cutting strip, which runs the entire cutting length, is attached by soldering or welding. The connection to the base body is also made by a V-shaped or dovetail-shaped holder in the front areas of the hard metal cutting strip. A similar design is specified in DE-OS 30 17 251.

The design of a saw blade with an attached hard metal cutting strip does have the advantage that the good bending and torsion properties of the base body made of cheap material are combined with the high hardness of the cutting teeth through the use of expensive hard metal. However, this material combination can lead to problems under high bending and torsion loads* In particular, the connection between the hard metal strip and the base body can be destroyed, causing the hard metal strip to break off * The risk of accidents is therefore not insignificant.

The well-known cutting bars with cutting teeth made of hard metal are generally attached to the base body by brazing or welding. Since the expansion coefficients of the two materials differ significantly, this manufacturing process also results in considerable stresses in the soldered or welded joint, which can also lead to premature breakage of the joint.

The invention is based on the object of proposing a saw blade, in particular a jigsaw blade, saber saw blade or the like, which avoids the aforementioned disadvantages and in particular can withstand considerably higher bending and torsional stress during use and in which the connection between

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Hard metal strip and base body in strength improved 1st.

This object is achieved according to the invention by means of the characterizing features of claim 1, starting from a saw blade of the type described in the introduction.

The invention is based on the knowledge that in order to avoid the disadvantages of the prior art, technical measures must be taken to reduce the bending stresses and torsional stresses in the hard metal cutting bar. This can be achieved according to the invention by dividing the hard metal cutting bar into segments so that expansion joints are formed to compensate for the stresses. The expansion joints form joints between the individual segments so that the hard metal cutting bar adapts completely to the base body in terms of its bending behavior and elasticity. The jigsaw blade according to the invention therefore combines the advantages of hard metal cutting teeth with the good bending and torsional properties of conventional jigsaw blades.

The measures listed in the subclaims enable an advantageous further development and improvement of the saw blade specified in the main claim.

& In the embodiment of the invention according to subclaim 2, the

Width of the expansion joint between the segments in the

The dimensions are a few tenths of a millimetre, where the expansion joint is preferably filled with solder.

} The width of the expansion joint is determined in conjunction with the

different expansion coefficients of the hard metal material and the base body during the soldering process

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determined, whereby the selected length of the segments also plays a role. The connection process during the soldering process should be carried out as stress-free as possible.

The design of the invention according to subclaim 3 provides that the expansion joints do not extend over the entire height of the hard metal cutting strip, so that in the area of the connection point a very narrow connecting bridge remains between the individual segments. This narrow connecting bridge serves to better handle, fix and adjust the segments during the soldering process without the basic bending properties or the joint effect between the segments being lost.

According to the development of the invention according to the dependent claim, some favorable dimensions for producing the invention are specified. Of course, other dimensions can also be selected as long as the effect according to the invention is retained. In particular, tooth shapes commonly used for jigsaws with different cutting geometries can be introduced into the segments.

The design of the invention according to subclaim 5 provides that, in a manner known per se, the width of the cutting teeth is greater than the width of the base body in order to avoid jamming of the jigsaw blade during use.

According to the development of the invention according to the subclaim, the connection cross-section between the segments and the base body is designed in different geometries for better adjustment and to enlarge the soldering surface.

According to subclaim 7, each segment should have at least two teeth* Preferably, however, several cutting teeth are used per segment.

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According to subclaim 8, the expansion joint should be arranged in the tooth base in order to avoid weakening of a cut tooth.

Further features and advantages essential to the invention emerge from the following embodiment, which is explained in more detail with reference to the drawing.

Fig. 1 is a side view of a jigsaw blade according to the invention and

Fig. 2a to 2e different embodiments of the

Cross section along section line I-I in Fig. 1.

The jigsaw blade (10) shown in Fig. 1 consists of a base body (11) made of a material as used in conventional jigsaw blades, ie of an alloyed tool steel with good operating properties, ie high toughness and high elasticity. The greatly enlarged saw blade shown in Fig. 1 usually has a cutting length of L 5 to 10 cm. The clamping shaft (1J2) is designed differently depending on the type of machine tool.

The jigsaw blade according to the invention has a narrow cutting strip (13) made of hard metal, whereby the cutting strip consists of several, usually equally long (length "1") segments (14). In Fig. 1, for example, five segments (14) are lined up one behind the other, which are arranged one behind the other at a distance "a" by expansion joints (15). The expansion joint (15) can extend over the entire height h of the segments (14). Alternatively, it is possible to use a small connecting web (16) with a thickness of only

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a few tenths of a millimeter remain to connect the individual segments (14) to one another. This has the advantage during the manufacturing process that the segments (14) remain individually fixed to one another and the fixing and adjustment to the base body (11) is simplified during the soldering process.

The distance "a" between the segments (14) depends on the different expansion coefficients of the shark metal material of the segments (14) and the base body (11). Depending on the length "1" of the segments (14), the different expansion of the materials is taken into account during the soldering process in such a way that the smallest possible stresses arise in the soldered connection (17) between the segments (14) and the base body (11). During the soldering process, the expansion joint (15) is also generally filled with solder. In special cases, however, it can also remain open. The joint effect between the individual segments (14) is decisive when the jigsaw blade is subjected to bending or torsional stress. The number "n" of segments (14) depends on the material properties of the different components. The more segments there are per cutting length "L", the better the adaptation of the bending stiffness of the cutting bar (13) to the base body (11). The ratio of the total cutting length "L" to the segment length "1" can be selected L:1 such as 10:1 to 2:1. The segment length is preferably about 1 w 1 cn, with a cutting length of L < 5 cm.

The ratio of the total height "H" to the segment height "h" is approximately H : h = 2:1 to 5:1. In particular, the height "h" of the segments is designed such that

the tooth height "h" has sufficient space. The &zgr;

However, the size "h" only needs to be slightly larger

rtls to be the desired tooth height "h ".

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The shape of the cutting teeth (22) is introduced into the hard metal strip in a manner known per se and in known cutting geometries, preferably by a diamond grinding process, namely after the soldering process, wherein the expansion joint (15) is preferably arranged in the tooth base (23) of the cutting teeth.

The connection between the cutting strip (13), consisting of individual segments (14) and the base body (11) is preferably made via the soldered connection (17). For this purpose, the connecting surface is geometrically adapted as shown in Fig. 2a to 2e.

In Fig. 2a and b, the segments (14) with a flat connecting surface (18) are applied using the brazing process. In principle, however, a welded connection is also possible.

In the illustration according to Fig. 2c, the soldered connection (1?) is designed as a connecting surface (19) with a circular segment shape in cross section. Similarly, the alternative embodiment according to Fig. 2d is designed as a V-shaped connecting surface (20) (Fig. 2d) and a U-shaped connecting surface (21) (Fig. 2e). The connecting surfaces (19 to 21) have the advantage that an enlarged and centered connecting surface is created between the cutting strip (13) and the base body (11), so that increased strength and easier assembly are possible.

Basically, the width "b" of the cutting strip (13) or the segments (14) is made wider than the width "B" of the base body (11). This can be achieved by a step between the parts (14 or 11) as shown in Fig. 2a, b, e or by a cortical design as shown in Fig. 2c, d

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happen* Due to the wider cutting edge or tooth strip (13) the teeth do not need to be set. In order to enable a free cut,

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JI Ii 11 io Jigsaw blade 11 Base body 12 Spannschaft 13 Cutting bar 14 Segments 15 Expansion joint 16 Connection point 17 Solder connection the flat connecting surface 19 cheese-shaped Connection surface Io V-shaped connecting surface II U-shaped connecting surface 12 Cutting teeth 13 Tooth base

Claims (6)

fl»i ·■ r* t» ·· I C 1· · ■ · 1 I SItI t ■■ ■ » " » > · Applicant: HAWERA Probst GmbH + Co. Schützenstraße 7980 Ravensburg official designation: "Saw blade" Claims: 1. Saw blade, preferably for one-sided clamping in a machine tool, such as a jigsaw blade, saber saw blade or the like, with a base body made of a material with high toughness or high elasticity, in particular made of alloyed tool steel and a narrow cutting bar applied thereon with geometrically defined cutting teeth made of a material with high hardness and thus low elasticity and toughness, in particular made of hard metal, characterized in that the cutting bar (13) consists of at least two segments (14) with stress expansion joints (15) in between, which are connected to one another and/or to the base body (11) via a soldered connection (17) or welded connection, whereby the length "1" of the segments (14) is dimensioned such that both during the manufacturing process stresses in the soldered connection or welded connection (17) and/or bending stresses or torsional stresses during use are avoided, fm» r 9 f · f · «■ · &igr; · · ···· &bull;&bull;&bull;« 2. Saw blade according to claim 1, characterized in that the expansion joint (15) between the individual segments (14) has a distance "a" in the order of a few tenths of a millimetre and that the expansion joint (15) is preferably filled with solder. 3. Saw blade according to claim 1 or 2, characterized in that the segments (14) are formed by incisions (15) are formed into a continuous cutting strip (13), wherein the incision (15) extends over the entire height "h" or only over almost the entire height "h" S S extends so that a connecting web (16) remains as a holding web between two segments (14) in the area of the solder connection (17) with the base body (11). 4. Saw blade according to one or more of the preceding claims 1 to 3, characterized in that the following dimensional ratios are applicable: a) Total height "H", segment height "h " H : h _s = 2:1 to 5 : 1 b) Total cutting length "L", segment length "1" L : 1 = 2:1 to 10 : 1 5. Saw blade according to one or more of the preceding claims 1 to 4, characterized in that the width "b" of the cutting teeth (22) is greater than the width "B" of the base body (11). 6. Saw blade according to one or more of the preceding claims, characterized in that the connecting cross-section (18 to 21) at the soldered or welded connection (17) between the segments (14) and the base body (11) is flat (18), curved (19), V-shaped (20) or U-shaped (21) in front view. 1. Saw blade according to one or more of the preceding claims, characterized in that at least two cutting teeth (22) are provided per segment (14). 8* Saw blade according to one or more of the preceding claims, characterized _in that the expansion joint (15) is arranged in the tooth root (23) of the toothing (22).