Cutting – Rotatable disc tool pair or tool and carrier – With means to support work relative to tool
Reexamination Certificate
1999-03-03
2001-06-26
Peterson, Kenneth E. (Department: 3724)
Cutting
Rotatable disc tool pair or tool and carrier
With means to support work relative to tool
C083S473000, C083S486100
Reexamination Certificate
active
06250191
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns a shearing assembly for cropping machines.
The invention is employed in automatic cropping machines suitable to shear elements shaped as rods or sheet, made of wood, plastic, metal, alloys or other suitable material.
The invention is particularly suitable, but not only, to be applied on double-bladed cropping machines which make two simultaneous cuts, of the type used to make frames for windows and doors, paintings or furnishing elements.
In the following description we shall refer to this specific use of the invention, although it can be used on other types of cropping machines, such as for example those with a single blade or those which are used to shear metallic foil, for example sheets of aluminium or similar.
BACKGROUND OF THE INVENTION
In the field of shearing machines, the state of the art includes cropping machines used to make frames for windows and doors, paintings or furniture; these machines are used to cut to size the elements which make up the frame, starting from a rod or continuous strip made of wood or similar material.
These cropping machines comprise a supporting structure with a horizontal work plane on which the rods which are to be cut are placed and fed forwards.
A shearing assembly is associated with the supporting structure and comprises a movable trolley supporting the blade or blades, or comprises as many movable trolleys as there are blades to move.
The blades can assume at least a working position, wherein they are taken into contact with the work plane where the rods are placed, in order for shearing to be carried out, and an inactive position wherein they are distanced from the work plane and are repositioned for the start of the next cycle. The blades have a shearing position lying on a plane substantially orthogonal to the work plane and angled at 45° with respect to the axis of feed of the rod to be sheared, so that they make a sloping cut on the rod; they are also arranged at an angle of 90° with respect to each other, so as to make two simultaneous and specular cuts of 45°.
The shearing assembly can travel in a pendular manner, if the shearing assembly follows an arched trajectory with a centre of rotation outside the work plane, or in a linear manner if it follows a rectilinear trajectory substantially orthogonal to the work plane.
The problem with state of the art cropping machines is that both in the ascent step and in the descent step the blades follow the same trajectory. This means that the sides of the blades, as they ascend, rub against the cut edges of the pieces resting on the work plane and clamped upstream and downstream of the shearing assembly.
This rubbing action can be even more harmful if there is even a little displacement of the two elements of the rod separated by the cutting action due to the release of tensions in the rod as it is cut. The rubbing damages the pieces, both in terms of lesions on the cut edge, and also in terms of scratches on the paint or the decorations.
The continuous rubbing of the sides of the blades may also cause them to wear prematurely, and the quality of the cut to deteriorate, so that the blades need to be replaced very frequently.
This same problem occurs substantially in every type of shearing machine comparable to the one described above, for example in shearing machines where the shearing assembly is movable horizontally, such as those used to shear to size metallic foils or sheets or metallic alloys.
The present applicant has designed, tested and embodied this invention to overcome the shortcomings of the state of the art and to obtain further advantages.
SUMMARY OF THE INVENTION
The invention is set forth and characterised in the main claim, while the dependent claims describe other characteristics of the main embodiment.
The purpose of the invention is to achieve a shearing assembly for cropping machines which, during the step when the blades are repositioned in the starting position, will allow the blades to pass in a position which does not come into contact with the cut edges of the pieces, thus preventing reciprocal damage.
The shearing assembly according to the invention comprises one or more blades mounted on a single movable trolley, or on as many movable trolleys as there are blades.
The shearing assembly includes means to move the at least one movable trolley; said movement means cooperate with mating guide means which create the constraint between the movable trolley and the supporting structure of the cropping machine and define the outward travel and return travel during the shearing cycle.
According to a first embodiment of the invention, the guide means include characteristics of at least partial elastic flexibility which allow the movable trolley to perform an elastic transverse movement, although limited, during its outward travel and return travel, if stressed by a force component which does not act on its centre of gravity.
When the stress is finished, the guide means are suitable to elastically resume their starting position.
According to another embodiment, when stressed by a torque component, the elastic transverse movement of the movable trolley is possible because the supporting structure of the shearing assembly is able to at least partly oscillate, for example in correspondence with an articulated clamping point or an at least partly elastic point.
According to the invention, the movement means are suitable to generate, either alone or in combination with the flexible guide means or the partly elastic clamp of the supporting structure, a torque applied to the movable trolley which causes it to move towards/away from the work plane.
These movements are correlated to the descent and/or ascent steps of the movable trolley, and are made possible by the partial flexibility of the guide means or the supporting structure. The movements make possible to define two different transit trajectories of the blades, one for the outward travel of the movable trolley and one for the return travel thereof.
In this way, the circular blades, during their return travel, pass in a position where they do not come into contact with the cut edges, so that the latter are not damaged.
When the stress caused by the activation of the movement means has ended, the elastic deformation of the guide means or the supporting structure is annulled and the movable trolley returns to its correct start-of-cycle and end-of-cycle position.
The entity of the deviation in the trajectory of the blades with respect to the normal trajectory without any torque applied can be regulated according to the working parameters such as the thickness of the blades, thickness of the rods, cycle speed, length of travel, etc., and must be correlated to the structural flexibility of the guide means or the supporting structure.
In one embodiment of the invention, the movement means consist of a pair of actuators, one prevailing over the other, constrained to the movable trolley at two points, advantageously symmetrical with respect to the position of the guide means and acting reciprocally in alternation, that is to say, while one is extending the other is contracting and vice versa.
The actuators are suitable to generate on the movable trolley a first torque in the outward travel step which takes the blades closer to the work plane, and a second torque, in the opposite direction to the first, during the return travel when the blades are distanced from the work plane.
The alternate activation of the two actuators causes the shearing assembly to descend and ascend, generating a tilting torque component on the movable trolley which causes a displacement in the opposite direction with respect to the work plane.
According to a variant, one of the two actuators is activated only in one of the two steps, either outward or return, of the operating cycle of the shearing assembly so as to generate the desired torque defining the modification to the trajectory between the outward travel and return travel.
According to a variant, instead of one of the two actuators there is a shock abs
Antonelli Terry Stout & Kraus LLP
Choi Stephen
Peterson Kenneth E.
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