WO2014180454A1

WO2014180454A1 - Shell-type milling cutter with replaceable blades for wood and wood materials

Info

Publication number: WO2014180454A1
Application number: PCT/CZ2014/000048
Authority: WO
Inventors: Miroslav Benes
Original assignee: Miroslav Benes
Priority date: 2013-05-04
Filing date: 2014-05-02
Publication date: 2014-11-13
Also published as: CZ26155U1

Abstract

A shell-type milling cutter with replaceable blades for wood and wood materials, in particular for the machining of wedge-shaped joints (finger joints). The body (1) of the milling cutter is provided, on one front side, with beds (2) for replaceable blades (3), the beds being at different levels (4) relative to the front side, where the different levels (4) are mutually shifted by the specific tooth pitch.

Description

Shell-type milling cutter with replaceable blades for wood and wood materials. Technical field The technical solution concerns a shell-type milling cutter with replaceable blades for wood and wood materials, especially designed for machining wedge-shaped joints, for example continuous dovetail.

Background Art

Several basic types of milling cutters or cutter heads are used for the production of wedge-shaped joints, especially for continuous joints, in the wood processing industry.

The cutters have soldered cutting portions, i.e. cutting tips, or cutting portions fixed in another manner. These tools can have cutting edges of hard metal (HM) or high-speed steel (HS) soldered, glued or fixed in another manner. Every such cutter machines multiple adjacent profiles of the wedge-shaped joint with the specific pitch. The soldered cutting portions can either be composed of several parts or form one unit, but the cutter always machines multiple pitches of the wedge- shaped / continuous joint - also called dovetails.

The disadvantage of these milling cutters is poor recoverability - if a tooth is broken, the cutter is basically destroyed; subsequent recovery is costly because it must be either supplemented with a new piece or repaired, and the latter is not always possible - depending on the scope of damage. At the end of the life of the cutting portions the milling cutters are usually thrown away, or new cutting edges have to be soldered or attached in another manner - this is time-consuming and costly. These milling cutters have bodies with little resistance - the bodies of these tools are usually made from basic grades of steel without any thermal or any other treatment, and therefore are not resistant to wear and can be easily damaged due to improper handling. Another disadvantage is lower durability, especially of soldered cutters, when their hardness is reduced during soldering due to the temperature required to solder the cutting portions and, as a consequence, their durability and life are significantly reduced. These cutters can be sharpened in only one way - the tools have to be sharpened as a whole, i.e. the body along with the blades, which requires a greater mass to be handled. These tools operate simultaneously, the cutters only alternate in the location of the cutting portions, which means that a large area is created on the workpiece at the same time - this results in a greater load on the motors, bearings and shafts. When sharpening cutters with attached cutting portions, the hard cutting portion is ground away together with the soft material of the carrier, i.e. the main body, which leads to the clogging of the grinding wheel and loss of its effectiveness, so that it needs to be cleaned, revived, by dressing, which reduces its life.

Milling wheels are also available with fixed cutting portions. These tools are always as thick as determined by the pitch to allow their incorporation into assemblies needed to machine different heights of wood. Cutting portions made of HM or HS are most often soldered to a body similar to a saw blade or fixed to it in another manner.

The disadvantages of these tools are their lack of compactness because when machining the required profile height, multiple bodies placed on each other are always necessary. Because of their thin bodies, usually 3.8mm, the bodies collapse and the entire assembly is unable to preserve its shape. This may result in wedges/dovetails of different thickness in the material, which makes it difficult or completely impossible to join two pieces together. Another disadvantage is their low stiffness, which causes chips and sawdust to easily get stuck between individual wheels, resulting in the deviation of the bodies and varying size of the wedges/dovetails in the workpiece. Individual workpiece are then either difficult or impossible to join. Another significant disadvantage is poor recoverability, since the cutter is virtually damaged when a tooth is broken. The subsequent recovery is very costly or time-consuming because it is necessary either to add a new unit or to repair it - depending on the scope of damage. At the end of the life of the cutting portion, the cutters can be usually repaired but this may not be possible for the entire assembly used. The bodies of these tools are usually made from basic grades of steel without any thermal or any other treatment, and therefore are not resistant to wear and can be easily damaged due to improper handling. Poorer durability is observed especially on soldered tools. The hardness of the cutting portions is reduced during soldering due to the temperature required to solder the cutting portions and, as a consequence, their durability and life are significantly reduced. Only one method of sharpening is possible for these tools - the tools have to be sharpened as a whole, i.e. the body along with the blades, which requires a greater mass to be handled.

Cutter heads with replaceable cutting tips or blades are also part of prior art. These cutting heads always consist of the cutter body and mechanically fixed cutting tips or blades, i.e. cutting portions seated in the bodies in different manners according to the manufacturer. If there are cutting tips fixed in the bodies, they always contain several adjacent pitches of the wedge-shaped/continuous joint; if individual blades are attached in the bodies, they are arranged next to each other and perform the same function as cutting tips, but separately on several parts.

If a tooth is broken on the cutting tip, the entire tip needs to be replaced. The tools have to exist in different widths so they could be arranged into assemblies depending on the required height of the joint because basic cutters mostly machine 8 "teeth", i.e. wedges of the specific pitch, next to each other and it is impossible to set them up into any dimension accurately. Another disadvantage is that for the production of covered/enclosed joints, e.g. for glued boards, it is necessary to use special wheels and cutting tips, or soldered tools, which need to be always placed on the edge of the assembly and one or several cutters are placed between them, with different thickness, so they are as close to the required dimension of the resulting joint as possible. Cutter heads are arranged together and, thanks to the width of the individual cutting tips or blades, always at least one or several tips penetrate the material across the width simultaneously, which results in a greater cutting resistance than if the material was penetrated by individual "teeth" as wide as a single pitch.

Essence of the technical solution

The deficiencies mentioned above are, to a large extent, eliminated by a shell-type milling cutter with replaceable blades for wood and wood materials, in particular for the machining of wedge- shaped joints, as specified in this technical solution. Its essence is that on one front side the cutter body is provided with beds for replaceable blades, positioned at least at two levels, where the individual levels are always mutually shifted by the specific tooth pitch.

The beds are advantageously arranged along the perimeter so that when at least two cutters are put together into a single assembly, the blades are arranged into a helix. The cutter body is provided with a lock for setting the blades into a uniform helix or for aligning them, wherein the locks are positioned such that the locks on one side of the body of one cutter head fit into the recesses on the opposite side of the body of another cutter head. The blades are advantageously attached to the body using screws, always one blade into one bed.

The design of this tool consists of a high-precision cutter body and replaceable blades, which can be made of different materials, such as HS or HM, and also of different shapes, i.e. profiles. The blades are fixed into the bodies using screws, always one blade into one bed. Each body consists of several beds placed at several, at least two, levels accessible always from one and the same side. The individual levels are always mutually shifted by the the specific pitch and the beds are placed to allow the installation of the necessary number of teeth, i.e. blades, on the tools in the same position, usually 2, 3, 4, 6, etc., and also to make sure that these blades can be arranged into a helix when several tools are arranged together into a single assembly.

The individual bodies have locks milled in them so that an even helix can be achieved by simply rotating them in the assembly; to simplify grinding, they can also be arranged in an opposite direction by rotating so that the blades in the individual cutters of the assembly are aligned and access to them is as easy as possible.

The mentioned technical solution allows to put the tools together so the blades ensure a helix- shaped cut. The cutting resistance is thus distributed among the individual blades which penetrate the material in sequence. For the tools as described in this technical solution, it is possible to use the most advanced and most powerful materials for their cutting portions, i.e. blades, to achieve the best possible durability of the cutting edge, thanks to their replaceability and optimized dimensions. The blades are not vulnerable to any thermal or any other unsuitable effects and can be even improved at no particular costs and protect them with different surface treatments. Along with greater durability and the possibility of a higher number of sharpening operations, the tools have a significantly longer life than any other tools. It is possible to replace blade assemblies in the individual cutter heads quickly and easily and to do so repeatedly.

The tools according to the present invention have, thanks to their easier penetration into the material, significantly lower energy requirements, especially as regards the electricity consumed during machining. Another advantage involves lower noise emissions because the tools as described in this technical solution are significantly quieter than other tools. At the same time they excel in quieter and smoother operation. Unlike other tools, they do not offer such resistance during cutting and the load on the drive motor is not so high. At the same time they can be used in machines with less powerful motors. The tools under the present technical solution are more productive and more efficient than other available tools. To achieve the required height of the machined material, the present solution makes it possible to arrange exactly as many cutter heads and blades as required because some positions in the bodies may not be fitted with blades. It is also possible to add blades into the individual levels of the assemblies, thus expanding or narrowing the assemblies by individual pitches. The present solution allows to use the same cutter heads for continuous as well as limited/encased continuous joints/dovetails - using only limit blades, and it also allows to use different profiles or sizes of joints. Any blades complying with the specific pitch can be always used in the same bodies. Thanks to the one-sided installation of the blades, this solution makes it possible to use a higher number of teeth in the individual diameters. For example, it is possible under this technical solution to use a tool with the diameter of 160mm as Z4, when four blades are mounted in the tool for each level, i.e. pitch. In this area of machine tools it is common to indicate the number of teeth as the number of sections containing cutting edges, but these are usually alternated because of the challenging profile, so that tools commonly referred to as Z4 work as Z2 and have to be considered as Z2 in the calculation of feed rates. In this technical solution, however, tools indicated as Z4 are actually Z4.

The tools as described in this technical solution can be made of top-quality materials, which can be further treated using the available technology and processes in order to enhance their resistance and reduce the effects on their wear, while increasing their resistance to the effects of improper handling.

Brief Description of Drawings

Examples of a shell-type milling cutter with replaceable blades for wood and wood materials according to this technical solution will be described in more detail on specific embodiments with the help of the attached drawings, where Figure 1 shows an embodiment of the milling cutter in axonometric view from the top, with blades. Figure 2 shows an axonometric view of this milling cutter from the top, without blades. Figure 3 shows an axonometric view of the assembly of milling cutters from the bottom. Figure 4 shows an axonometric view of the assembly of milling cutters from the top. Figure 5 shows an assembly of milling cutters in a position for the grinding of blades. Figure 6 shows an axonometric view of another embodiment of the milling cutter. Description of Embodiments

In the embodiment of a shell-type milling cutter with replaceable blades for wood and wood materials, in particular for the machining of wedge-shaped joints, the body 1 of the milling cutter is fitted, on one front side, with beds 2 for the replaceable blades 3, mounted at several levels 4, where the individual levels 4 are always mutually shifted by the specific tooth pitch. The beds 2 are arranged along the perimeter so that when at least two cutters are put together into a single assembly, the blades 3 are arranged into a helix. The cutter body 1 is provided with a lock 5 for setting the blades 3 into a uniform helix or for aligning them, wherein the locks 5 are positioned such that the locks on one side of the body 1 of one cutter head fit into the recesses on the opposite side of the body 1 of another cutter head. The blades 3 are attached to the body 1 using screws 6, always one blade 3 in one bed 2.

The exemplary body 1 of the cutter for the cutting diameter of 160mm with the number of teeth Z = 3, for the pitch of DIN 3.8mm, has an active width of the body 1 B = 4 3.8 = 15.2 mm. There are 12 beds 2 for the blades 3 in the body 3. The total width of the body 1 and of the milling cutter for the installation of blades 3 is, including the locks 5, 21.2 mm at the bottom. The cutter heads are fastened to the shaft of the machine, d = 50 mm, and clamped using the clamps, d = 75 mm. In another embodiment there is a body 1 of the cutter for the cutting diameter of 250 mm, with the number of teeth Z = 6 for a pitch of DIN = 3.8 mm. The active width of the body 1 is B = 4 3.8 = 15.2 mm. There are 24 beds 2 for the blades 3 in the body 3. The total width of the body 1 and of the milling cutter for the installation of blades 3 is, including the locks 5, 21.2 mm at the bottom. The cutter heads are fastened to the shaft of the machine, d = 50 mm, and clamped using the clamps, d = 75 mm.

The tools are sharpened either in a bundle, i.e. with fully fitted cutters, or the blades 3 are removed from the cutter heads and sharpened in a jig, or clamped in a magnet and propped by a support. Industrial Applicability

The shell-type milling cutter with replaceable blades under this technical solution can be used in particular in the wood-processing industry, especially for the machining of wedge-shaped joints.

Claims

P A T E N T C L A I M S

1. A shell-type milling cutter with replaceable blades for wood and wood materials, in particular for the machining of wedge-shaped joints, characterized in that the body (1) of the milling cutter is fitted, on one front side, with beds (2) for the replaceable blades (3), mounted at several levels (4), where the individual levels (4) are always mutually shifted by the specific tooth pitch.

2. The shell-type milling cutter as in Claim 1, wherein the beds (2) are spaced along the perimeter so that when at least two bodies (1) of the milling cutters are put together into one assembly, the blades (3) are arranged into a helix.

3. The shell-type milling cutter as in Claim 1 or 2, wherein the body (1) of the milling cutter is provided with a lock (5) for setting the blades (3) into a uniform helix or for aligning them, where the locks (5) are positioned such that the locks on one front side of the body (1) of one cutter fit into the recesses on the opposite side of the body (1) of another cutter.

4. The shell-type milling cutter as in any one of the preceding claims, wherein the blades (3) are attached to the body (1) using screws (6), with always one blade (3) in one bed (2).