WO2008041248A1

WO2008041248A1 - Device for automatically positioning cutters on planing heads

Info

Publication number: WO2008041248A1
Application number: PCT/IT2006/000703
Authority: WO
Inventors: Riccardo Garniga
Original assignee: Autoplanus Ltd
Priority date: 2006-10-03
Filing date: 2006-10-03
Publication date: 2008-04-10
Also published as: EP2073965A1

Abstract

Described is an automatic positioning device for locking cutters (12) in planing heads (17) with maximum precision, especially planing heads used for working wood or like materials, said heads consisting of a block (10) of generally cylindrical or truncated cone shape in which suitable slots (11) for accommodating the cutters or blades (12) are formed. The blades (12) are held in place by plugs (13) comprising protruding parts (15, 16) forming undercuts designed, on one side, to receive the rake face (19) of each blade (12) and, on the other side, to abut against the edge (21) of the slot (11) in the block (17), said blades (12) and plugs (13) being operatively retained in the block (10) by screws (14) inserted in threaded holes (14').

Description

"DEVICE FOR AUTOMATICALLY POSITIONING CUTTERS ON PLANING HEADS"

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TECHNICAL FIELD

This invention relates to an automatic positioning device designed to lock cutters in planing heads with maximum precision, especially planing heads used for working wood or like materials.

More specifically, the invention relates to a device for mechanically engaging a planing head and whose characteristic feature is that it comprises locking means that guarantee that the cutter will be positioned in place with the maximum precision.

This engagement device, which enables tools to be positioned more precisely and securely, comprises suitably shaped plug-like components whose special shape allows a cutter to be positioned precisely and extremely easily in the respective slot.

This invention applies to the production of cutting tools for planing heads used for working wood or like materials.

BACKGROUND ART

It is known that in the cutting, routing and planing tool industry, there are numerous different solutions that vary on the basis of tool type and mounting system.

For planing certain types of substrates, mainly wood, special planing heads are used which consist of a substantially cylindrical or pyramidal block on which a plurality of blades are mounted.

The blades, which may also be of reversible type, are fitted to the planing head block using any of several different techniques designed to hold them securely in place while at the same time allowing them to be removed and replaced as quickly as possible when worn or broken or, if of reversible type, when they need to be turned around.

For this purpose, the blades are mounted in suitable slots made in the planing head block and held in place in the slots by means of screws positioned radially or tangentially relative to the workpiece. One disadvantage of this type of solution is that the task of replacing blades when damaged or worn or when blades of a different kind are required for a new process may be a very laborious task requiring great care and skill. All the plug retaining screws must be slackened, being careful to hold the mounting block with the hands to stop it from falling out, and the blade then removed.

The procedure must be followed in reverse to fit the new or replacement blade, that is to say, the blade must be inserted into the slot with one hand while the plug is inserted with the other, after which all the screws must be inserted and tightened with relatively complex movements of the hands.

Since the blades are distributed longitudinally on the entire cylindrical surface, they must be precisely adjusted at the same radial distance from the central shaft. This, at present, is a complex and laborious task that that has to be carried out by trial and error.

Some traditional systems are hydraulically locked by means of steel liners located at each end of the hole in the head. Grease is pumped at high pressure into the cavities between the head walls and the liners. The two cavities are interconnected so that when the grease is pumped into one cavity, the other cavity is filled automatically. The pressure exerted by the grease causes the liners to expand towards the shaft.

This type of lock, though it makes centring easier and more effective, is unduly complex because the planing head must be provided with suitable cavities and passages for the grease, as well as cumbersome grease injection pumps which are disproportionate to the relative simplicity of the operation to be performed.

In other cases, the planing head blades are positioned with the aid of specially designed aligners. These aligners are even more complex than the grease pumping systems and comprise elaborate equipment with magnetic clamps, a set of gauges, magnetic stops, and a precision stop screw located at the centre of the clamp. Thus, this traditional adjustment system, too, is unduly complex and involves considerable practical difficulties, especially if we consider that a planing head may mount a large number of blades which, if changed and adjusted by traditional means, are time-consuming, labour intensive and uneconomical.

DESCRIPTION OF THE INVENTION

This invention has for an aim to provide a device for mechanically adjusting planing head blades, especially for working wood or like materials, that can overcome or at least reduce the above mentioned drawbacks .

Another aim of the invention is to provide an automatic device for positioning planing head blades that is simple and inexpensive to make and hence economically advantageous .

According to the invention, the above aims are achieved by an automatic device for positioning planing head blades which is designed to hold the planing blades -A- in place in their slots and whose characteristics are described in the main claim.

The dependent claims describe advantageous embodiments of the invention. The automatic positioning device according to the invention comprises, at suitable slots made around the circumference of the planing head, self-positioning elements designed to keep the cutters, even if sharpened, lined up with the outermost circle described by the cutters because the rake face of each cutter abuts against a specially-designed plug which in turn abuts against the planing head block.

The main advantages of the invention, besides all those deriving from constructional simplicity, lie in the fact that it reduces the cost of labour for changing the blades.

This is because when a blade is changed or adjusted, the retaining plug causes the blade to abut with its rake face exactly against the inner side of a specially shaped guide formed on the plug which also has another guide which in turn enables the plug itself to be positioned relative to the block that forms the planing head. This makes it very easy for the operator to position and align the cutters correctly. The positioning of the blades is further facilitated by magnets which cause the blades to adhere to the cutter block while they are being positioned.

DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will become evident on reading the following description of one embodiment of the invention, given as a non- restricting example, with the help of the enclosed drawings, in which: - Figure 1 illustrates the plug and the respective cutter held in place in its slot;

- Figure 2 is a schematic section showing an exploded view of an automatic positioning device according to the invention for holding a cutter in place in a planing head;

- Figure 3 is a schematic section view of a detail of the plug, in an embodiment of the invention while it is being positioned relative to the cutter; - Figure 4 is a detail view showing a part of the plug positioned relative to the cutter after the cutter and the plug have been placed in the working position in their slot in the planing head.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

The device according to the invention is used for fixing cutters on a planing head of the type consisting of a block 10 of generally cylindrical or truncated cone shape in which suitable slots 11 for accommodating cutters or blades 12 are formed.

The novel feature of the invention lies in the fact that the blades 12 are held in place by specially-shaped plugs 13 operatively retained in the block 10 by screws 14 inserted in threaded holes 14', arranged preferably in tangential fashion relative to the block but which may also be arranged radially.

More specifically, the plugs 13 have a substantially flat shape, relatively thick so that they can be inserted into the slot 11 together with the respective blade 12, and have a specially shaped top end illustrated in detail in Figures 3 and 4.

The shape is given by a first protrusion 15, extending in the direction of the blade 12 and a second protrusion 16 extending in the direction of the edge 17 of the slot 11 opposite the blade 12.

As shown in Figure 3, the protrusion 15 of the plug 13 has an abutment surface 18 inclined in a direction parallel to the inclined surface or rake face 19 of the cutter 12, whilst the protrusion 16 has an abutment surface 20 that is parallel to the outer edge 21 of the block that forms the head 17.

This special shape and arrangement of the plug 13 permits exact self-positioning of the cutter change/positioning system.

Indeed, when the cutter 12, whether new or sharpened, is fitted, it always lines up with the circle

"D" described by the ends of the cutter rake faces so that the planing head is always in perfect working order without necessitating further adjustment.

This is made possible by the fact that the rake face 19 of the blade 12 abuts against the plug 13 and the plug 13 in turn abuts against the edge 21 of the head 17.

The invention also contemplates the provision of a magnet 22, which is seated in a suitable recess in the plug 13 and which facilitates removal and replacement of the cutters, enabling quick and easy actions.

On the side of the plug 13 opposite the magnet 22 there is a recess 23 whose shape enables the locking grub screw 14 to be guided into the exact position.

To fit and exactly position the blade 12, all the operator has to do is place the blade 12 against the edge of the plug 13, where the magnet 22 causes it to adhere, make sure that the cutter face 19 comes into contact with the face 18 of the plug protrusion 15 and insert the cutter 12 and plug 13 into the slot 11 of the head block 10, making sure that the abutment surface 20 comes perfectly into contact with the outer edge 21 of the block that forms the head 17 . At this point, it is sufficient to operate on the grub screw 14, which is already in the threaded hole and just needs to be tightened in the recess 23 in the plug 13. Advantageously, the magnet might be housed in any suitable position in the slot 11 in the cutter block.

According to another embodiment, inside and at the bottom of the slot 11 into which the blade and plug are inserted, there might be elastic elements such as springs or the like to exert pressure tending to push the blade and the plug outwards.

In this case, fitting the components is even easier since the plug 13 just needs to be pressed into the slot while the special shape of the plug itself exactly lines up all the components.

In this case, too, tightening the grub screw 14 keeps the plug/blade assembly securely in position in the slot.

The invention is described above with reference to a preferred embodiment. However, obviously the invention can be modified and adapted in several ways using technically equivalent elements and without thereby departing from the scope of the inventive concept.

Claims

1. An automatic positioning device for locking cutters in planing heads with maximum precision, especially planing heads used for working wood or like materials. said heads consisting of a block (10) of generally cylindrical or truncated cone shape in which suitable slots (11) for accommodating the cutters or blades (12) are formed, the device being characterised in that the blades (12) are held in place by plugs (13) comprising protruding parts (15, 16) forming undercuts designed, on one side, to receive the rake face (19) of each blade (12) and, on the other side, to abut against the edge (21) of the slot (11) in the block (17), said blades (12) and plugs (13) being operatively retained in the block (10) by screws (14) inserted in threaded holes (14').

2. An automatic positioning device according to the foregoing claim, characterised in that the plugs (13) have a substantially flat shape, relatively thick so that each can be inserted into the slot (11) together with the respective blade (12), and have a specially shaped top end consisting of a first protrusion (15), extending in the direction of the blade (12) and a second protrusion (16) extending in the direction of the edge (17) of the slot (11) opposite the blade (12), the first protrusion (15) and the second protrusion (16) forming containment and abutment undercuts .

3. An automatic positioning device according to either of the foregoing claims, characterised in that the protrusion (15) of the plug (13) has an abutment surface (18) inclined in a direction parallel to the inclined surface or rake face (19) of the cutter (12), whilst the protrusion (16) has an abutment surface (20) that is parallel to the outer edge (21) of the block that forms the head (17).

4. An automatic positioning device according to one of the foregoing claims, characterised in that when the cutter (12), whether new or sharpened, is fitted, it always lines up with the circle "D" described by the ends of the cutter (12) rake faces, since the rake face (19) of each blade (12) abuts against the plug (13) and the plug (13)^" in turn abuts against the edge (21) of the head (17).

5. An automatic positioning device according to one of the foregoing claims, characterised by a magnet (22) seated in a suitable recess in the plug (13) and designed to facilitate removal and replacement of the cutters (12).

6. An automatic positioning device according to one of the foregoing claims, characterised in that on the side of the plug (13) opposite the magnet (22) there is a recess (23) whose shape enables the locking grub screw (14) to be guided into the exact position.