IT8320444A1 - MACHINE FOR THE APPLICATION OF METALLIC SEWING STITCHES ON CARDBOARDS AND SIMILAR - Google Patents

Description

DESCRIPTION of the industrial invention entitled "MACHINE FOR THE APPLICATION OF METALLIC SEWING STITCHES ON CARDBOARDS AND SIMILAR"

SUMMARY

A sewing machine for applying staples for sewing to sheets of cardboard and the like provides an oscillating head capable of applying two or more at the same time. stitches aligned for each cycle, said stitches having a predetermined distance between centers. Does the sewing head have two or more? secondary sliders, rigidly connected for movement, and a primary slider. The secondary slides are associated with as many spindles for the formation of the C-shaped staples obtained from a power supply d? continuous strip.

The invention relates to a machine for applying metal sewing staples to sheet materials, typically but not exclusively, cartons for packaging and the like.

It is known how packaging cartons are obtained starting from suitably cut and printed cardboard sheets which are joined along an edge by applying a series of metal staples or sewing staples applied to the carton which is still folded flat. A car of this type? substantially constituted by a plane of advancement of the cardboard and by a sewing head that moves with a pendular motion around a fulcrum. harmonica, as well as? by the necessary dragging and control devices. During a part of the cycle or revolution, the head provides for the formation of the metal stitches, substantially constituted by a segment of C-folded metal strips, which are subsequently driven in and riveted when the stitching head descends into contact with the advancing material.

The sewing pitch P, that is? the distance between two consecutive points applied could be varied by adjusting so much the speed? of advancement of the cartons (increasing which increases the pitch and vice versa :), how much by adjusting the speed? rotation of the sewing head (increasing it decreases the pitch and vice versa). In practice, however, you opt to keep the rotation speed of the head constant (in particular the maximum reasonably allowed by the kinematic mechanics) and you vary the speed? of passage of the cardboard. The relationship between the different quantities involved? the following

P = V / Np

where P? the sewing pitch, V? the speed? in meters / minute and Np the number of points applied per minute.

The choice ? dictated by the preference of controlling the adjustment on only one part of the machine for reasons of saving and simplification. It should also be borne in mind that the sewing head is started by a clutch controlled by an electromechanical control which allows it to be brought to rotation speed; the head within a very small angle in order to have the harmonic motion with a speed? very close to the nominal one. In particular, it is necessary to avoid tearing the cardboard, repeating the point in an incomplete way, etc.

Currently, on conventional machines, oscillating or not, the stitches are applied with sewing steps predetermined by an electronic programming.

Sometimes ? need to increase the density? of the points applied to the junction of the cardboard, so as to obtain, also for the junction, a resistance equal to that of the base cardboard. The step can? then go down to 25-30 mm. and consequently the speed? of passage of the cardboard under seam must be drastically reduced according to the equation

V = P .Np

The equation clearly shows the contrast between the different needs as to get a step more? small you should also reduce the speed? of passage and therefore ultimately the productivity? of the car.

It is therefore an object of the present invention to provide a machine for applying metal stitching staples to cardboard and the like which is capable of sewing with a density. of remarkable points while admitting high speeds? of passage of the card.

? ' another object of the present invention is to reduce the number of sewing cycles by the head at par. of points applied. How will it come? explained more? in detail below, the machine according to the invention? able to apply two or more? stitches for each rotation cycle.

It is a further object of the invention that of realizing the application of the stitches according to the modality. details in order to improve the use of the machine and the production of cartons. The invention will come? now described in a preferred embodiment with reference to the accompanying drawings in which:

Figure 1 schematically shows a sewing machine according to the invention capable of applying; two stitches at each descent of the head;

Figure 2 is a perspective view of the main slide-secondary slide-mandrels assembly of the machine of Figure 1;

FIGURE 3? a side view of this complex; FIGURES 4 and 5 illustrate the operation of the sewing machine; And

Figures 6 and 7 illustrate the structure of an improved knife adapted to vary the size of the stitch.

The preferred embodiment? the one capable of applying two stitches for each descent of the head, in this case the ratio between the increase in stitches and the structural complication of the machine being optimal, however the invention is not? limited to this particular configuration that will come? also described in view of its greater simplicity? constructive.

With reference to Figures 1 and 2, a closed or folded cardboard box 10 is transferred from the folding section to the sewing section.

In the sewing section the box is transported by a pair of superimposed belts 11,12 within which? arranged the cardboard. The speed? of transport ? initially elevated and constant in the first part of the path (V-j in figure 5) so that the cardboard moves rapidly towards the sewing head

30 in order to reduce downtime. A photocell 14 suitably placed before the sewing head reads the position of the advancing box and starts the sewing program previously set on a console of the electronic control apparatus. The speed? of the tapes, and therefore? of the closed box, is then reduced according to a suitable ramp (RQ in figure 5) at a speed? Vp calculated through the equation V = P.Np where the step? that of sewing and at the same time the count for the start of the head starts. The first point on the box can? in fact, be placed at a widely variable distance A from the edge of the box according to the set programming.

Once the programmed position has been reached, the head is started which, according to the preferred embodiment of the invention, comprises a main slider 1 and two secondary sliders 3 adapted to engage with as many mandrels 2 for the formation of the sewing points. ? mobile thanks to a system of connecting rods 32-33 driven by the main engine of the machine. The sewing stitches5 They are obtained from two flat plate feeds 20 and 30. How does the machine work? the following .

The spindles 2 simultaneously enter under the slider 1 which is raised and simultaneously transport the flat plates 20,30 for the formation of the point. Slider 1 goes down, cut the plates a. measures and then folds them around the spindles 2. The primary slider 1 then continues its descent while the secondary sliders 3 are lowered, moving away the spindles 2 which leave the points cos? formats.

The 5 points formed, meaning with what? the C-shaped elements are pushed downwards towards the material to be sewn by the secondary sliders 3 which also determine their riveting. Subsequently, the secondary sliders 3 rise again following the rotation movement of the head, leaving the points with center-to-center I stapled in the box. bypass of the secondary lanes 3? approximately equal to the speed? of the sewing material. As the head continues its rotation to perform another stitch-forming cycle, the sewing material continues to move at the speed. V (in meters / minute) necessary to carry out step B.

Using two secondary cursors, if the wheelbase I? equal to 35 mm. and it is desired, for example, to obtain all the points spaced by the same amount, the pitch B is adjusted to 70 mm., which implies a speed? of passage of the double box of that which would be had with a single secondary cursor. Being the number of the boxes sewn, proportional to the speed? of passage of the box, you get an increase in productivity? what can? also be 100%.

Alternatively, having to apply a certain predetermined number N of stitches on a certain portion of cardboard, the number of revolution of the head? equal to N / 2 and therefore? will be reduced? in the middle? the number of stresses on the kinematic mechanisms. As far as wear is concerned, these too will spread in principle on the split system of stitch formation.

Once the cardboard sewing is finished, the speed? of transport will come? brought back to the V1 value (UZ ramp) for the rapid ejection of the cardboard from the machine.

With reference to Figure 4? the block diagram of the machine control system is shown.

It comprises a central processor EC which receives the signals coming from the photocell 14, from a movement control encoder, from a reference sensor of the braking and of the number of sewing cycles as well as by a reference sensor of the stitch re-tapping position. The computer in turn controls the drive of the direct current motor for the movement of the webs and the brake and friction of the sewing head through the asynchronous motor for the movement of the head.

The conveyor belts are controlled directly by the direct current motor piloted by the relative drive and the sewing head is rotated from a standstill and brought to the fixed rotation speed by the clutch and electromagnetic brake unit.

The electronic control processes the data written by the operator on the console and controls the operation of the conveyor belts, starts the electromagnetic clutch and controls the linear movement by means of the encoder with millimeter resolution.

As an example, the speed? initial of the cardboard on the ribbons can? be 160 meters per minute, going down to a lower value that remains constant throughout the sewing cycle to achieve! the desired step B. The encoder controls the space covered by the cardboard by transmitting the information to the central processor. If the pitch set? small, the speed? of seam? low compared to the initial one and therefore the ramp is very inclined. In practice yes? found that? preferable that the departure of the head occurs when the cardboard is already moving? at speed? constant cos? that the parameters of advance departure of the same are clarified. Since? there? Not ? always possible ,? provided a control that, when the narrow steps are chosen (that is, low speeds), automatically reduces the speed? fixed transport (ie less than 160 meters / minute) according to pre-established parameters cos? that the system is able to bring itself in speed? of stitching before the departure of the head occurs. Is it optimized cos? the performance of the stapler by imposing high speeds? when we? ? possible.

From the moment in which the cursor repeats the first point, an additional count starts which makes a comparison with a cyclic subroutine comparing the actual distance reached B with the set one and automatically reduces or increases the speed? of the cardboard according to the waste so as to rectify the position of the second pair of stitches.

With reference to Figures 6 and 7, a further improvement of the invention is illustrated consisting of a knife 62 which can be removed from the guides 61 of the staple formation matrix, in order to rapidly change the length of the cut plate necessary for the formation of the stitch on the heads. sewing. the knife? fixed with screws 63 on the die guide body 61 and is removed and replaced in order to rapidly vary the dimension K which defines the cutting position of the plate. The knife is removed every time you intend to change the cutting size of the plate and its replacement is quick. ? just remove any? easily accessible screws while the body remains positioned on the primary slide.

Bench? the invention has been described with particular reference to a head capable of applying two aligned stitches, it evidently extends to cover even those modified embodiments which provide for three or more? secondary sliders with relative spindles for the application of three o

Claims (7)

1. A machine for applying sewing staples to sheet material, the type in which the material to be sewn advances at high speed. constant under a head oscillating around a fulcrum, characterized by the fact that the head comprises a single primary slider connected to at least two secondary sliders, and as many spindles associated with the secondary sliders for forming the staple, the spindles being mounted on the head aligned according to the sewing direction and with a fixed distance. 2. Machine according to claim 1, characterized in that the sewing head comprises several? point formation systems and that the points are formed simultaneously and reaffirmed by more? secondary slides rigidly connected to each other. 3. Machine according to claim 1 or 2 characterized by the fact that it is equipped with a cyclic control of the sewn length which automatically intervenes on the adjustment and that the speed? approaching jerk is variable with respect to the step to be carried out. ^. Machine according to claim 3 characterized by the fact that the control system provides a processor: which receives signals from a photocell, from a cardboard position encoder and from sensors, respectively for braking and number of cycles, and for the position and re-typing of the stitch, this processor generating logic signals for the actuation of the movement of the head movement belts and of the corresponding clutch and brake. 5- Machine according to claim 4 characterized by the fact that the speed? advancement is constant and high due to the approach of the cardboard, and this speed? it then falls rapidly to a steady state value maintained for the entire duration of the seam, and that said speed? it therefore goes back to the previous high value for the ejection of the sewn cardboard. 6. Machine according to any one of the preceding claims, characterized by the fact of providing knives having different dimensions inserted, with different fixing systems, on the guide body of the die, said knives being able to be removed from the body in order to vary the length of the cut sheet. 7. Machine for applying metal staples: for sewing on a sheet material substantially as described and illustrated.