FI67128B - ANORDNING FOER ATT FRAESA TORV - Google Patents

Description

67128

PEAT MILLING EQUIPMENT - ANORDNING FÖR ATT FRÄSA TORV

The present invention relates to a device for milling peat from the surface of a bog, the device comprising a milling drum mounted on a drive device known per se, such as a tractor, rotating substantially transversely in the direction of travel, the surface of which is provided with one or more milling blades oblique to the tangent to the milling drum.

The name milling drum is due to the way the blades move, not so much to the frame structure of the milling machine, so in milling technology the milling drum refers to various rotating milling members.

In milled peat production, the first actual work step is milling, in which the surface layer of a 10 ... 20 mm thick peat field is usually milled into powder. From the point of view of drying and use, it would be advantageous for the grain size of milled peat to be relatively large, of the order of 10 ... 20 mm.

Current milling machines fall far short of this goal, e.g. due to the inhomogeneity of peat and milling constructions.

The most common so-called spike milling cutters usually grind peat to a grain size of less than 5 mm. Harrows give coarser peat, but the scatter is too great. In addition, the surface of the field becomes soft and uneven, which makes it difficult to collect milled peat and move the machines.

Other fields related to soil treatment in one way or another are known from the German application DE-OS 30 32 204, a roller quarry which resembles and is similar to a peat mill. DE-A-272 819 and US-A-3,226,855 disclose helical ditch milling cutters, which, however, make them completely unsuitable for their milling tasks and conditions compared to peat milling.

Currently, the cheapest milling machines are known to be the so-called Rauss milling machine and the so-called screw cutter. The former is a so-called passive ___ _______ - · TT— 2 67128 milling machine with a frame as a bed, so the Kent & n surface remains smooth. In a tough and hard field, this machine does not work well. The screw mill gives a coarser peat than other active mills ("Peat Industry" 1979/3 pp. 17-22), but the result is not as good as would be desirable.

Looking more closely at screw milling, it can be seen that in this type of milling the load is applied to the blade mainly in the direction of the blade, which is why the blade must be made of a relatively thick material and the cut is practically with a blunt blade. The result is a relatively higher milling resistance and a grinding effect.

The object of the present invention is to improve the durability of a screw milling type blade so that the main load on the blade is applied in the direction of its plane and not against the blade blade as in current milling cutters. At the same time, the aim is to improve the quality of milling by using a high circumferential speed for cutting, but a low axial speed for peat transfer. Such a slit cut, at a suitable humidity, gives a favorable plow-slice-like work pattern for drying in certain types of peat, in which the slits are oriented in the direction determined by the axial and travel velocity vectors. The invention is characterized in that the direction of the ridges of the milling cutter blade or blades in the groove surface is almost parallel to the direction of travel of the milling drum during milling. In this way, the blade encounters the peat and the hard materials in it, such as wood, mainly in the direction of the plane of the blade, in which direction the blade is thus subjected to the greatest stresses. In this way, the above-mentioned method of milling peat is approached, in which the peat is actually moved at a low axial speed, while the cutting itself takes place violently at a high circumferential speed.

A preferred embodiment of the invention is characterized in that the angle of inclination of the screw blade or blades or the lateral pitch of the individual blades is less than 10 ° with respect to the tangent of the cutting circle of the milling drum. In this way, a low axial transfer rate is simply achieved. Tur- 3 67128 defect material is often inhomogeneous, including e.g. wood and tough fibers that would require a high cutting speed, and a more brittle often amorphous material that should be removed at a low speed to obtain coarse granules. By using a small increase in the thread of the blades, a low axial speed is achieved even at high speeds.

A preferred embodiment of the invention is also characterized in that the axis of the milling drum is rotatable with respect to the direction of travel of the device in order to obtain a suitable cutting angle. In this case, milling drums with a blade pitch angle of more than 10 ° can also be used. Since the quality of the peat layer varies greatly in most bogs, the machining properties of the cutter can be easily adjusted in this way, for example from the tractor cab.

A further preferred embodiment of the invention is characterized in that the rotational speed and / or the direction of rotation of the milling drum is adjustable. Milling with a screw-type cutter gives the coarsest stuff if the peat just comes off the surface of the field. The milling parameter setting corresponding to this point varies depending on the peat type. Variable milling parameters include, in addition to the rotation of the aforementioned milling drum axis, the speed of the milling drum and the working depth.

Another preferred embodiment of the invention is characterized in that the milling drum is conical. In this way, the chest angle of the blades can be reduced in the axial section.

Another preferred embodiment of the invention is characterized in that a plurality of milling drums can be pulled in succession with either the same or different handed blade cutting angles. If two successive milling devices are used in the direction of travel, they should preferably be one left-handed, the other right-handed.

In addition, a preferred embodiment of the invention has

_ .. TTT

4 671 28 is characterized in that the screw blade is toothed and / or provided with cutting elements. Cutting can be intensified in this way to cut wood and tough fibers.

A preferred embodiment of the invention is further characterized in that the sides of the blades are covered with a material with low friction relative to peat, such as Teflon. This further reduces the load on the blade due to the removal of the peat and the comminution of the peat.

A further preferred embodiment of the invention is further characterized in that the pitch of the screw blade is at most four times the working depth with a 1-thread milling cutter and eight times with a 2-thread cutter. Such a structure is a prerequisite for obtaining a work mark resembling a plow incision.

A further preferred embodiment of the invention is further characterized in that the circumferential speed of the cutting movement of the blades is at least five times the axial speed. Fibrous and woody peat has a high shear rate of more than 15 m / s, which is generally necessary for successful cutting, whereas instead the removal rate should be as low as possible, at least less than 3 m / s, to prevent unnecessary grinding. With brittle peat, the removal rate should be even lower.

The presented milling principle is also advantageous in bog clearing-milling and profiling and leveling screwing, where the peat layer is treated deeper than in a production mill, up to a depth of more than 0.5 m. The peat material is then wetter and softer than on the surface, so the difference with respect to tough fibers such as Eriophorum, Scheuzgeria, etc. and wood is emphasized. Thus, the advantage of successful machining is that it can be done with a high cutting speed and a sharp blade that does not clog and does not cause high cutting pressure and lateral displacement during machining. This is relatively possible with the 5 67128 cutter according to the invention.

The invention will now be described in more detail by way of example with reference to the accompanying drawing, in which

Fig. 1 shows a milling according to the invention with a 1-thread screw blade,

Fig. 2 shows a milling according to the invention with separate milling cylinders,

Fig. 3 shows a milling according to the invention with a conical milling drum,

Fig. 4 shows two sequentially pullable cutters according to the invention,

Fig. 5 shows the milling cutter according to Fig. 1, in which the screw blade is provided with teeth 11a.

Figures 1 and 2 show a rotating log 1 belonging to a milling device, which is attached to the tractor substantially transversely to the direction of travel. A screw blade 2 or helically rotating separate blades 3 can be attached to the surface of the drum 1, as shown in Figures 1 and 2. Irrespective of the quality of the blade, the pitch angle α, which is also marked on the dryers 1 and 2, is essential. The correct pitch angle α is used to achieve the correct relationship between the circumferential speed and the axial linearity velocity components and V &. This angle must be less than 10 °, which can be obtained directly by the angle of inclination of the blades or by turning it with respect to the direction of travel of the cutter, so that a cutter with a larger angle of inclination of the cutter fulfills the above condition of up to 10 °.

One way to reduce the axial peat transfer resistance of the cutter is to use a conical cutter body 4, as shown in Fig. 3. The conicity of the drum 4 reduces the chest angle of the 6 67128 blades in the axial section, even if the above angular condition is met.

Efficient peat release is achieved by the arrangement according to Fig. 4, in which two different-handed milling machines 5,6 are arranged in succession.

Figure 5 shows a cutter suitable for cutting tough peat, the blade 7 of which is provided with teeth. Such toothing may also consist of fixed or removable cutting pieces which can be mounted on a normal cutter only when the situation so requires.

As such, the milling devices shown are suitable for efficient milling of peat. For more flexibility and efficiency, the cutters can be modified as needed while driving, for example directly from the tractor cab. The parameters to be modified are e.g. the angle of the cutter shaft in relation to the direction of travel, the speed and direction of rotation of the cutter drum and the working depth of the cutter.

It will be clear to a person skilled in the art that the various embodiments of the invention are not limited only to the example given above, but may vary within the scope of the claims set out below.

Claims (10)

A device for milling peat from the surface of a bog, the device comprising a milling rack (1) mounted on a traction device known per se, such as a tractor, rotating substantially transversely in the direction of travel, provided with one or more milling blades known obliquely to the cutting tangent of the milling drum. , that the direction of the ridges of the milling cutter blade or blades (2,3,7) in the groove surface is almost parallel to the direction of travel of the milling drum (1) during milling. Device according to Claim 1, characterized in that the angle of inclination of the screw blade or blades (2) or the lateral angle (α) of the separate blades (3) is less than 10 ° with respect to the tangent to the cutting circle of the milling drum (1). Device according to Claim 1 or 2, characterized in that the axis of the milling drum (1) is rotatable with respect to the direction of travel of the device in order to obtain a suitable cutting angle. Device according to Claim 1, 2 or 3, characterized in that the rotational speed and / or the direction of rotation of the milling drum (1) are adjustable. Device according to one of Claims 1 to 4, characterized in that the milling drum (4) is conical. Device according to one of Claims 1 to 5, characterized in that a plurality of milling drums (5, 6) can be pulled in succession with either the same or different threaded blade cutting angles. Device according to one of Claims 1 to 6, characterized in that the screw blade (7) is toothed and / or provided with cutting elements. ___ - ITT 8 67128 7 67128 Device according to one of Claims 1 to 7, characterized in that the sides of the blades (2,3,7) are covered with a material with low friction relative to peat, such as Teflon. Device according to one of Claims 1 to 8, characterized in that the pitch of the screw blade (1.7) is at most four times the working depth with a 1-thread milling cutter and eight times with a 2-thread cutter. Device according to one of Claims 1 to 9, characterized in that the circumferential speed (V 1) of the cutting movement of the blades is at least five times the axial speed (Va). 67128