Technical field
[0001] Two-corner dinking machine
Technical field
[0002] The present invention belongs to the sector of the paper working machines and specifically
to the sector of the machines specialized in cutting the paper used to coat boxes
for valuable packings.
Prior art
[0003] The boxes used to contain valuable products, for instance leather goods, luxury shoes,
perfumes or the like, are often made of cardboard coated by fine paper. Whereas cardboard
provides the necessary sturdiness, paper coating is used to enrich the appearance
of the box and of its respective cover. The paper coating is put on an already formed
cardboard box hence, in order for paper to well adhere to the substrate, it is necessary
that it is properly shaped, account being taken of the dimensions of the box to be
coated as well as of the required flap. In the case of a box having the form of a
regular parallelepiped, the shaped paper substantially get the form of a cross in
which the opposed arms are identical two by two; all arms protrude by a length equal
to the summation of the height of the box to be coated plus the inner flap.
[0004] Typically two arms have a width equal to the length of two sides of the box, whereas
the remaining two arms are wider, because they incorporate the flaps used to coat
the edges of the box.
[0005] More specifically, the cross shape is completed by a number of cuts having the shape
of a semi-"V" in each point where the arms cross each other. The purpose of this cut
is to make it possible to fold the side flaps without causing wrinkles.
[0006] Two main technical solutions are known for long time in this sector to shape paper.
[0007] The former solution is based on the use of a dedicated flat dinking die, in which
a plurality of metal blades held by a planar support, typically made of wood, duplicates
the exact perimeter of the paper to be obtained. The second solution is based on the
use of a special machine tool, a so called notching machine, the latter being usually
equipped with two adjustable notching devices, mounted on a movable cross-member capable
of moving down and up. In correspondence with every downward movement of the movable
cross-member, the notching devices simultaneously shape two of the four corners of
the stack of paper sheets.
[0008] In notching machines, every corner of the sheet is removed thanks to the action of
a notching device; the latter supports a combined action of two blades, called front
blade and side blade, cooperating with a front counter-blade and a side counter-blade
respectively. The front blade and the side blade form a substantially right angle
in the plane.
[0009] The positions of the blades and of the counter-blades in the cutting plane are adjustable,
so that one machine is capable of preparing paper coatings suitable for different
boxes.
[0010] In order to completely notch a stack of sheets two cutting operations are necessary,
as a matter of fact, after the first cutting operation, in order to complete the notching
of all sheets, it is necessary to take the partially notched stack off, to turn it
by 180 degrees, and then to insert it again into the machine for a subsequent downwards
movement of the movable cross-member which performs the last two notchings. Both notching
devices move simultaneously and each device comprises one front blade and one side
blade; both these blades exert their cutting action by cooperating with their respective
fixed, front and side counter-blades.
[0011] It is worth to note that both solutions mentioned above feature some drawbacks.
[0012] The use of a flat dinking die is very expensive in the case that sheets are to be
cut for boxes of different dimensions, because every cutting geometry requires the
construction of a specific dinking die. On the other hand the use of a dinking die
makes it possible to obtain very accurate cutting perimeters, featuring so called
two-corner notchings, i.e. notchings featuring a small angular cut in correspondence
with each of the corners of the box to be coated, so as to prevent the flap from overlapping
internally to every edge. In the present description this cut will be called secondary
cut or secondary notch and the cutting assembly that performs it will be called secondary
cutting assembly or pressure cutting assembly, whereas the assembly used to perform
one of the two main, or primary, notchings will be referred to as main, or primary,
cutting assembly.
[0013] Another advantage of a cut obtained by means of a flat dinking die consists of the
possibility of shaping the cutting perimeter in such a way as to take account of the
thickness of the cardboard used to manufacture the box to be coated.
[0014] This effect is accomplished by modifying the semi-"V"-shaped cut into an asymmetric
"V"-shaped cut.
[0015] In notching machines, to take the thickness of the cardboard into consideration,
the asymmetric "V"-shaped cut effect is obtained thanks to a slight tilt of the side
blades with respect to the front blades, so as to form an angle between each other
slightly greater than a right angle. However this solution prevents the edge of the
coating paper from being perfectly parallel to the edge of the box, which results
in an unpleasant final appearance.
Objects and brief description of the invention
[0016] As it will be evident from the following description, the machine according to the
present patent application allows to overcome both drawbacks affecting the two solutions
presently offered by the state of the art known so far.
[0017] All that is accomplished by installing on a traditional notching machine two innovative
secondary pressure cutting assemblies, each comprising an original angular blade and
at the same time by conveniently modifying the ends of the profiles of the two side
blade and counter-blade pairs by chamfering them.
[0018] Installing two secondary pressure cutting assemblies makes it possible to add to
a traditional notching machine the possibility of performing two notchings simultaneously,
each of which being a double-corner one, in other words the machine according to the
present invention is capable of performing two primary notchings and two secondary
notchings.
[0019] Each one of the secondary pressure cutting assemblies comprises an upper fixing block
(5) and an innovative angular blade (3), its cutting edge being located below; the
angular blade (3) is mounted on a blade-holder (6) which is slidingly coupled with
the body of said upper block (5), the secondary cutting action is accomplished by
pressing the angular blade (3) against the stack of paper put on the working surface.
[0020] The pressure cutting assemblies (8) are mounted on devices of a known type which
allow to adjust their position with respect to the working surface of the machine,
so as to be able to determine the position where to perform the secondary notching
accurately.
[0021] According to an embodiment of this invention the secondary cutting assembly is arranged
in such a way that the blade-holder (6) is capable of going back a little bit inside
the block, by winning the contrasting action exerted by appropriate compression elastic
means (4).
[0022] The upper fixing block is mounted on the movable cross-member of the notching machine,
which drives the alternating vertical movement of the main cutting assemblies.
[0023] The cutting action performed by the second notching takes place owing to the downwards
movement of the cutting assembly (8) until the angular blade (3) starts cutting the
stack of sheets to be notched, then the downwards movement proceeds until the blade
(3) reaches the base of the stack of sheets, thus compressing the elastic means (4);
this way the pressure cutting assembly is capable of also notching those sheets which
are located at the very bottom of the stack.
[0024] It is necessary to point out that the pressure cutting assembly is just one of the
possible embodiments of the present invention, as a matter of fact a similar effect
might be obtained by using cutting assemblies not provided with compression elastic
elements and where the downwards movement of the angular cutting tool is operated
by an oil pressure or pneumatic system or by another known device.
[0025] There are two possible alternatives: according to a former technical solution the
secondary cutting assembly is mounted on the movable cross-member and is provided
with independent means for making the blade and blade-holder go down with respect
to the upper support connected to said movable cross-member; according to a second
solution the secondary cutting assembly might be independent of the movable cross-member,
but in any case be provided with independent means for making the blade go down and
performing the secondary notching.
Brief description of the drawings
[0026]
- Fig. 1 shows the two primary cutting assemblies of a notching machine of a traditional
type; the secondary notching is asymmetric-"V"-shaped and the two side blades are
not parallel, but form a small acute angle.
- Fig. 2 shows the two primary cutting assemblies of the notching machine according
to the present patent application, where the movable front blades (11, 21) and side
blades (12, 22) as well as the fixed front counter-blades (13, 23) and side counter-blades
(14, 24) are highlighted. The position of the angular blade (3) is also shown.
- Fig. 3 shows the two primary cutting assemblies illustrated in figure 2 along with
the outline of a paper sheet with two double notchings only.
- Fig. 4 shows the two primary cutting assemblies illustrated in figure 3 along with
the outline of a paper sheet with four double notchings.
- Figure 5 shows a front view of the movable main cross-member of the machine which
highlights the main cutting assemblies (1, 2), the front and side blades and counter-blades,
as well as the two secondary pressure cutting assemblies (8); the cross-section line
"VI-VI" referred to in the next figure is also shown.
- Figure 6 shows the cross-section "VI-VI" of the secondary pressure cutting assembly
(8) which highlights the upper block (5), the blade-holder (6), the angular blade
(3) and the compression elastic means (4).
- Figure 7 shows a magnified detail of the ends of the side blades (12, 22) and of the
counter-blades (14, 24) to highlight the chamferings (19, 29) present on said side
blades and on their respective counter-blades.
Detailed description of an embodiment of the invention
[0027] The machine according to the present patent application comprises two main cutting
assemblies (1, 2) adjustably mounted on a vertically movable cross-member; whenever
the movable cross-member goes down said main cutting assemblies (1, 2) simultaneously
go down to simultaneously perform the two main notchings of the stack of sheets put
by the operator on the working surface and make it move forward up to an abutting
line.
[0028] Each one of the two main cutting assemblies (1, 2) comprises a front blade (11, 21)
and a side blade (12, 22), fixed to each other and both integrally movable together
with the main cross-member, said blades cooperate with their corresponding lower front
counter-blades (13, 23) and side counter-blades (14, 24); the lower counter-blades
are not constrained to the cross-member, but they are integral with the working surface.
Cutting takes place whenever the upper blades are lowered down to engaging their corresponding
fixed counter-blades.
[0029] The position in the working surface of the blades and of the counter-blades making-up
the two main cutting assemblies is adjustable by using known methods, to adjust the
position of the notchings both with respect to the centre line of the machine and
with respect to the abutting line of the stack of paper sheets.
[0030] This adjustment can be made manually, by making the assemblies slide on graduated
cursors and then blocking them thereto, alternatively it is possible to use lead nuts
and worms, or even other systems.
[0031] One of the advantageous effects the machine according to the present patent application
is surprisingly capable of achieving originates from the presence of two innovative
compression secondary cutting assemblies; each of these assemblies comprises an upper
support block (5) inside which a blade-holder (6) is slidingly coupled with; an angular
blade (3) is associated with said blade-holder, its cutting edge facing downwards.
[0032] The blade-holder (6) can be made slide with respect to the block (5) by means of
a variety of devices of known types, for instance an oil-pressure system.
[0033] According to a practical and inexpensive embodiment of this invention, the sliding
movement of the blade-holder (6) is contrasted by the action of specific compression
elastic means (4) housed inside the upper block (5); the latter is in turn connected
to translational means which make it go down toward the stack of sheets, in a direction
parallel to the direction according to which the blade-holder (6) slides in the supporting
block (5); said translational means make the cutting assembly (1) go down to cause
the angular blade (3) to press in turn the stack of sheets in order to completely
perform the second notching. A perfect secondary cutting of all sheets of the stack
is obtained thanks to the combined effect of the downwards action exerted onto the
angular blade (3) by the translational means and by the contrasting elastic means
(4).
[0034] To adjust the position of the secondary notching with respect to the main notching,
the position of both pressure cutting assemblies (8) is adjustable with respect to
the centre line of the machine, in this case too the means for adjusting the position
of the compression cutting assemblies (8) are of a known type.
[0035] According to a preferred and economically advantageous embodiment of this invention
said elastic means (4) consist of one or several helical springs.
[0036] According to a particularly complete and improved embodiment the rectilinear cutting
edge of said side blades (12, 22) presents a chamfering (19, 29) in correspondence
with the front end, so that the cut made features an asymmetric-"V"-shaped profile,
not a semi-"V" shaped one, this way the perimeter of the shaped paper takes account
of the thickness of the cardboard that the box is made of; consequently both lower
side counter-blades are shaped in such a way as to fit the chamfering present in the
upper side blades (12, 22).
1. A machine for the double notching of a stack of paper sheets to coat boxes, in which
the main notchings are performed by means of two descending main cutting assemblies
(1, 2), each comprising a front blade (11, 21) and a side blade (12, 22), both movable
and cooperating with a front lower counter-blade (13, 23) and a side lower counter-blade
(14, 24) respectively, the position of said blades and counter-blades being adjustable
on the working surface, characterized in that it comprises at least one secondary pressure cutting assembly (8) connected above
to translational means that press it above said stack of sheets to perform a secondary
notching.
2. A machine according to the previous claim, characterized in that said translational means consist of the main movable cross-member of the notching
machine.
3. A machine according to one or several of the previous claims, characterized in that said at least one secondary pressure cutting assembly comprises an upper fixing block
(5) and a lower angular blade (3), the latter mounted on a blade-holder (6) slidingly
coupled with said upper fixing block according to an axis parallel to the sliding
axis of said translational means.
4. A machine according to one or several of the previous claims, characterized in that the descending cutting action of said angular blade (3) with respect to said upper
fixing block (5) is caused by specific means.
5. A machine according to one or several of the previous claims, characterized in that the descending cutting action of said angular blade (3) with respect to said upper
fixing block (5) is caused by specific elastic means (4).
6. A machine according to one or several of the previous claims, characterized in that said elastic means (4) are driven into compression whenever the downwards movement
of said translational means pushes said angular blade (3) against the stack of sheets
to be notched located on the working surface.
7. A machine according to one or several of the previous claims, characterized in that said elastic means (4) comprise a helical spring.
8. A machine according to one or several of the previous claims, characterized in that the position of said at least one secondary pressure cutting assembly (8) is adjustable
with respect to the working surface of the machine.
9. A machine according to one or several of the previous claims, characterized in that the rectilinear cutting edge of said side blades (12, 22) presents a chamfering (19,
29) in correspondence with the front end.
10. A machine according to one or several of the previous claims, characterized in that said lower side counter-blades are shaped in such a way as to fit said chamfering
present in said upper side blades (12, 22).