EP1190820A2 - Spirally shaped knife - Google Patents

Abstract

The rotary cutting blade has a spiral cutting edge following the non-linear functional correlation formula r=f( alpha ) where r' is the distance of cutting edge from the rotation area of the blade, alpha ' is angular distance with respect to a zero line and f' is a mathematical function, where f(x) is a non-linear function.

Description

The invention relates to a cutting knife, in particular a Cutting knife for a slicing food Cutting machine, the cutting knife being rotatable about a The fulcrum can be stored on the edge of the cutting knife arranged cutting edge is formed spirally, wherein the cutting edge at least in sections in polar coordinates formulated the following functional relationship follows: r = f (Α). Here r describes the distance of the cutting edge from Pivot point, α describes the angular distance with respect to a Zero line, i.e. an angle, and f describes any one mathematical function.

The aforementioned cutting knives are used in cutting machines that are used for Slicing strands of food such as baguette sausages or Loaves of cheese are provided. In such cutting machines become, for example, industrially manufactured sausages or strands of food (with considerable weight and considerable Length) cut on an industrial scale. Known Machines achieve between 600 and 1,000 cuts per minute.

There are two for separating the product slice from the product loaf Concepts known. The first one is disc-like Cutting knife placed on a planet-like rotor that periodically circulates and the product loaf regularly for one Feed releases. Since the construction of the knife drive is relatively is complicated, the use of spiral is also Knives known. The advantage with spiral cutting knives lies in the fact that, with an appropriate design of the cutting knife, moving the cutting knife away from Product for which it is not necessary to carry it forward. To do this, use the spiral shape on the cutting knife appropriate paragraph provided, which is used in the to move the product forward at the right moment. It is clear that the use of the spiral knife the elaborate planetary drive can be saved.

In the known spiral knives, the cutting edge is guided according to an Archimedean spiral. There is a linear relationship between the distance r from the cutting edge to the fulcrum and the angular distance α (the angle), expressed in polar coordinates: r = k * α.

The use of the following according to an Archimedean spiral Spiral knives are not used in high-performance cutting machines optimal. With high-performance cutting machines, the aim is generate at least 1000 cuts per minute.

When the product slice is separated from the product loaf two different ones, perpendicular (or orthogonal) to each other arranged force components to be taken into account. At the pulling cut, the cutting knife moves parallel to Product surface, or it becomes the force component described, which is tangential to the cutting knife.

The force component of the is arranged at right angles to this pressing cut, the radial and with respect to the circular knife acts perpendicular to the surface with regard to the product.

Now it turns out that when using the known cutting knife the speed of rotation in high-performance cutting machines of the spiral knife must be increased accordingly. This leads to the force component of the pressing cut so is great that no clean cut is made, but that Slice is literally chopped off the loaf.

The aforementioned cutting machines are, for example, in the German one Publication 195 14 407, German Patent 38 33 596 and in German utility model 91 16 036.

The German utility model 91 16 036 describes one cutting knife designed as an Archimedean spiral, which with cutting teeth in the direction of rotation in the rear area Is provided. Such a configuration of the cutting knife is relatively complex, it should also be noted that the cutting surface of the individual teeth then under different Cutting angles act on the material to be cut and so under Circumstances force components that lead to an unclean one Make cut.

The German Offenlegungsschrift 195 14 407 as well as the Patent 38 33 596 divide a spiral cutting knife in several sectors, with Archimedean spiral, the respective design in the different sectors different are. This is also intended to improve the cutting result , although with the inconsistent transition between the sectors (German Offenlegungsschrift 195 14 407) also with impairment of the cutting result to calculate. The German patent 38 33 596 increases in middle sector massive the radius increase over the two outer areas, which leads to a corresponding adjustment of the relative cutting angle and also at constant Rotation speed of the cutting knife the cutting speed and the pressure force increases and so z. B. torn out Guide slices or incorrect cuts in the material to be cut can.

In the known disc-like circular knives existed in addition to the rotational speed of the rotor, which yes the cutting effect determines, also the possibility that Increase the rotation speed of the circular knife itself and thus the force components of the pulling step accordingly to increase and so even at high rotation speeds or high performance of the machine to cleanly separated Slices to arrive.

It is therefore the object of the present invention made a cutting knife as described above to improve this even for use at high speeds leads to usable cuts.

To solve this problem it is proposed that instead of known linear relationship between the angle α and the Distance r of the cutting edge to the fulcrum is a non-linear one Function is selected. It is therefore proposed that mathematical function between the distance r and the Angle α exists so that the degree of the function descriptive polynomial is not equal to 1. It is therefore possible for example a square or higher functional Choose context. But it is also possible to have a connection to choose whose degree of polynomial is less than 1 to Example r ≈ √α. Deviating from the classic Archimedes Spiral form has been found that the Angle of attack of the cutting knife when immersed in the product is changed so that the component of the pulling Cut compared to the component of the pressing cut is increased and so, even at high cutting speeds, a clean cut is made.

In the preferred embodiment of the invention it is provided that the cutting edge is arranged within an Archimedean spiral contour, the following mathematical relationship being valid: r = f (α) <k * α + a for α> 0.

Here k is the gradient factor and a is the radius at α = 0 ° his.

Following a well-known Archimedean spiral Cutting knife is provided a constant slope over the angle. This leads to different pitch angles Scope and on the other hand a relatively large pitch angle at the beginning of the spiral and consequently too proportionate large force components of the pressing cut. The means that the chopping effect at the beginning of the knife is proportionate is high, especially when immersing the Knife into the product at the beginning no notch effect of the already separated pane part can be used in the product can to facilitate the cutting of the product. By the advantageous development of the invention such that the Cutting edge within an Archimedean spiral follows, (at same starting radius) becomes the share of the pressing cut significantly lowered at the beginning, which means the chopping effect in principle is reduced and especially at the beginning of the Cutting a clean stab in the knife to be cut Well done.

According to the invention it is proposed that the functional relationship r = f (α) in an interval of α with the lower limits from 0 ° to 100 ° and the upper limit from 245 ° to 345 °. It is provided that the cutting knife according to the invention not only on a statically oriented drive shaft is operated, but also rotated on a rotor becomes. Similar to the well-known circular knife discs the rotor movement is then exploited to at the time of Approval of the product to advance the product again. ever after how the cutting knife is used, a smaller one or larger interval for the functional relationship - as described - provided. In the preferred embodiment it is envisaged that the functional relationship at 0 ° starts.

The upper limit can be between 245 ° and 345 °. It is but also known the functional relationship after a certain angle at which another context is chosen will start (for example with a constant radius). Prefers is assumed to be the upper limit for this interval 300 °, which then results in a range of 60 ° in which the Product is released to promote this.

In a preferred embodiment of the invention provided that the functional relationship r = f (α) so is chosen that the force portion of pulling and pushing Cut over the effective cutting edge length in one constant ratio. This relationship exists especially when the knife is immersed in the material to be cut, the ratios are chosen so that none Chopping action occurs. In a preferred embodiment it is provided that the pulling and pushing The proportion of force in the cut is the same and the ratio is therefore the same 1 is.

Due to the constant balance of power along the effective Cutting edge length, the product disc is always the same Parameters separated and no need to change Boundary conditions are observed during the cut.

In a preferred embodiment of the invention is found that it is beneficial if the functional relationship r = f (α) is chosen so that the force portion of the pulling Cut is greater than the force portion of the pressing cut. Such a configuration ensures that the the cutting process more favorable pulling cut when cutting outweighs and thereby the unwanted chopping movement by chopping the disc of the material to be cut avoided is reduced.

In a further development of the invention it is provided that the functional relationship r = f (α) is composed of a plurality of sub-functions g _{i which} abut one another. This can be described mathematically as follows:

It is possible that these sub-functions abruptly abut each other at their limits β _{i, k, ...} , the discontinuity, for example, can lead to a visible kink or step on the cutting knife, or that the discontinuity, for example, in a selective change of the pitch angle on the circumference (which is synonymous with a discontinuity in a derivative dr / dα).

It is beneficial, however, if it is ensured that the Transition continuously at the borders between two sub-functions is filled in to avoid any unwanted tears or To produce chips in the material to be cut. The preferred Design of course depends on the speed of rotation or the exact conditions in the transition area.

In a preferred embodiment of the invention it is provided that the contour follows a logarithmic spiral and the functional relationship is essentially as follows: r = f (α) = a * e k * α

The use of a logarithmic spiral for the spiral shape the cutting knife has the advantage that along the circumference constant slope angle exists. A constant follows from this Relationship between pushing and pulling cut, which makes the cutting process much easier to control. In contrast to an arithmetic spiral, the logarithmic spiral at the end of the spiral (approx. at 270 ° up to 345 °) a larger pitch angle is offered, but it works it is favorable here that the immersed in the material to be cut Cutting knife already has a notch effect in the material to be cut and therefore a larger cutting angle seen in rotation later angle segment does not lead to an undesired chopping movement leads. At the same time, chopping when immersed of the knife into the product due to the lower pitch angle when the knife is immersed in the material to be cut suppressed. With this configuration, therefore, at the same time achieved two mutually complementary, positive properties.

In a variant of the invention, it is provided that the nonlinear function is not a cosmic spiral of shape r = f (α) = a * cos (k * α) follows. With this cosmic spiral, the force components of the pressing cut are significantly larger than the force components of the pulling cut, which may result in undesired chopping or hacking under certain circumstances when the knife penetrates the material to be cut as well as with a corresponding increase in the force component of the pressure cut during the engagement of the cutting knife in the material to be cut Can result in tears in the material to be cut. A section-by-section use of the cosmic spiral should not be provided for here either.

The invention relates not only to the advantageous Design of the cutting knife, but describes it also a slicer (commercially available as a "slicer" known) with a cutting knife as described above. The either on a statically mounted drive shaft or on a moving drive shaft, a rotor that - like also known - for example on a planetary drive Seat. Seen from above, the shaft also forms the fulcrum of the knife. The existing on the spiral knife circumference Paragraph can be used to display the product in the To advance the time segment where sales release the product. As an alternative to this, the rotational movement of the rotor is used used. It has been found that an inventive Cutting machine equipped with the described Cutting knife is equipped with very good cutting results High speed cutting machines (from 1500 revolutions 1500 cuts per minute). The thing to be cut open Product (for example sausage or cheese loaf) lies on a if necessary also inclined, contact surface.

A feed device is provided for the timely Feed of the material to be cut in the direction of the cutting knife provides.

The claims now filed with the application and later are attempts to formulate without prejudice to achieve further protection.

The backward relationships mentioned in the dependent claims point to the further training of the subject of the main claim by the features of the respective subclaim out. However, these are not considered a waiver of achievement an independent, objective protection for the characteristics to understand the related subclaims.

Features previously only disclosed in the description can in the course of the process as of essential to the invention Significance, for example to differentiate it from the prior art be claimed.

Claims (10)

Cutting knife, in particular for a slicer cutting a foodstuff, the cutting knife being rotatable about a pivot point and the cutting edge arranged at the edge of the cutting knife being of spiral design, the cutting edge, at least in sections, formulated in polar coordinates, follows the following functional relationship: r = f (α) With

r:

Distance of the cutting edge from the fulcrum

α:

Angular distance with respect to a zero line (angle)

f:

Mathematical function,

characterized in that f (α) is a non-linear function. Cutting knife according to claim 1, characterized in that the cutting edge is arranged within an Archimedean spiral contour, wherein r = f (α) <k * α + a (for α> 0) applies with

k:

Slope factor and

a:

Radius at α = 0.

Cutting knife according to one or both of the preceding claims, characterized in that the functional relationship r = f (α) in an interval of α with the lower limit of 0 ° to 100 °, preferably 0 ° and an upper limit of 245 ° to 345 °, preferably 300 °. Cutting knife according to one or more of the preceding claims, characterized in that the functional relationship r = f (α) is selected so that the force component of the pulling and pushing cut of the cutting knife over the effective cutting edge length is in a constant ratio and in particular this ratio is the same 1 is. Cutting knife according to one or more of the preceding claims, characterized in that the functional relationship r = f (α) is selected such that the force component of the pulling cut is greater than the force component of the pressing cut. Cutting knife according to one or more of the preceding claims, characterized in that the functional relationship of several sub-functions g _{i is} as follows

is composed, which also meet discontinuously at their limits β _{i, k, ...} Cutting knife according to one or more of the preceding claims, characterized in that the cutting contour follows a logarithmic spiral and the functional relationship essentially r = f (α) = (a * e k * α ) reads. Cutting machine, according to one or more claims, characterized in that the non-linear function is not a cosmic spiral of shape r = f (α) = a * cos (k * α) describes. Cutting machine, in particular high-performance cutting machine with a performance of 600 to 2000 cuts per minute, preferably of about 1500 cuts per minute, with a Cutting knife according to one or more of the preceding Claims where the good to be cut, for example a strand of food like a sausage, a loaf of cheese or other food on a product pad rests and is conveyed against the cutting knife, which separates slices from the food strand, Cutting machine according to claim 9, characterized in that the cutting machine has a shaft which forms the fulcrum of the cutting knife, and the shaft is designed to be stationary or movable, for example in a rotor.