PETROGALLI ANGELO (IT)
| US5539182A | 1996-07-23 | |||
| US4038513A | 1977-07-26 |
| 1. | A process for microperforating hides using a laser, characterised by: positioning the hide below a plurality of laser sources disposed substantially aligned along a straight line perpendicular to the hide advancement axis, each laser source being provided with a galvanometric head comprising deflector mirrors, activating the laser sources to generate a first series of holes, the total triggering, ionization and quenching time of each laser source to form a hole being less than 10 psec., each laser source generating, during the ionization stage, a pulse of power greater than its rated power for a time less than the rated working time, operating the deflector mirrors repetitively, alternately with the repetitive activation of the laser sources, to generate successive series of holes until completion of the field of action of the galvanometric head, advancing the hide/laser sources through a further length corresponding to the length of the hide surface treated by the galvanometric head measured in the direction of advancement of the hide/laser sources. |
| 2. | A process as claimed in claim 1, characterised by forming holes with a diameter of about 40 um. |
| 3. | A process as claimed in claim 1, characterised in that the holes are of conical shape. |
| 4. | An apparatus for forming microperforations in hides in accordance with the process claimed in claims from 1 to 3, characterised by comprising: a plurality of mutually aligned laser sources, each of which is provided with a galvanometric head comprising deflector mirrors movable at high speed under the control of a numerical control system, means for supporting the hide below said laser sources, the axis of alignment of the laser sources being transverse to the axis of advancement of the hides, means for the stepwise advancement of the hide/laser sources which alternately halt the hide/laser sources during hole formation and cause it or them to advance through a length corresponding to the length of that surface of the hide pertaining to the field of action of the galvanometric head measured in the direction of advancement of the hide/laser sources. |
| 5. | An apparatus as claimed in claim 4, characterised in that the laser sources are mounted on a bridge frame. |
One of the great drawbacks of hide articles, such as clothes, shoes <BR> <BR> etc. , is known to be their virtual lack of transpiration, which consequently imposes a limitation on its use for this purpose, and on its use as a covering for sofas, chairs and in particular motor vehicle seats.
US-A-5539182 describes a process which uses a laser beam to perforate the leather of motor vehicle seats in order to increase its permeability to moisture. The leather treated has a thickness varying from 0.5 to 5 mm, the holes having a diameter between 60 and 1000 pm with an interhole spacing between 2 and 5 mm.
To implement this process a laser apparatus is provided, which micro- perforates the leather in a C02 environment and moves along the leather in steps equal to the interhole spacing.
This process presents however certain drawbacks and in particular : - it requires the presence of a protective gas, COs, in order to eliminate the drawback of burning along the edges of the holes, - operative slowness due to the movement of the apparatus.
According to the invention all these drawbacks are eliminated by a process for micro-perforating hides as described in claim 1.
To implement the process, the invention provides an apparatus as described in claim 4.
A preferred embodiment of the present invention is described in detail hereinafter with reference to the accompanying drawings, in which: Figure 1 is a side view of an apparatus for implementing the process of the invention, in which only one laser source is shown for simplicity, Figure 2 is a plan view thereof.
As can be seen from the figures, the process for micro-perforating hides uses a laser apparatus consisting of a plurality of laser sources 2, preferably of C02 type, mounted aligned on a bridge frame 4 situated in a position overlying a conveyor belt 6 provided with a drive motor 12, and on which the hide 8 to be treated is extended.
With the exit of each laser source 2 there is associated a galvanometric head 10 of known type, comprising deflector mirrors which move at high speed under the control of a numerical control system in such a manner as to direct the laser beam successively onto several points of a predetermined surface.
The apparatus of the invention also comprises a control device (not shown in the drawing) provided with suitable software and hardware, to: - reduce the triggering and quenching times of each laser source in passing from the formation of one hole to the next, so that, for equal ionization times, the advancement speed can be increased and a greater number of holes hence be obtained, - during the making of the holes, generate ionization pulses having a greater power (about 3 times) than the rated power of the laser beam for a very short time of the order of some us,
- move the deflector mirrors of the galvanometric head during the triggering and quenching of the laser sources.
The apparatus of the invention operates in the following manner: the hide which advances along the conveyor belt 6 is halted below the laser sources 2 which are activated so as to generate a first series of holes in the hide.
Then during the quenching stage of the laser sources the control device causes the deflector mirrors of the various galvanometric heads to move in such a manner that the next activation of the laser source generates a second series of holes separate from the first series, this operation being repeated until the entire hide surface pertaining to the field of action of the galvanometric head is perforated.
In this manner a plurality of micro-perforations of preferably conical shape are formed in the hide, to emerge at the visible surface, they having a diameter of about 40 um and being practically invisible.
The motor 12 is then operated to again advance the hide through a length corresponding to the length of the surface of the field of action of the galvanometric head, this length being measured in the advancement direction of the hide.
From the aforegoing it is apparent that the process of the invention presents numerous advantages, and in particular : - it enables the hide to be worked at high speed by virtue of the presence of the galvanometric head and the reduction in the triggering, ionization and quenching time of the laser,
- it does not require the presence of protective gas, - by virtue of the large pulse in the ionization stage, it enables holes to be produced without burning their edges, - it enables lasers of lower rated power and hence of lower cost to be used, - by suitably setting the control system for the deflector mirrors, it enables holes to be made in a predetermined pattern.
In a modified embodiment, not shown in the drawings, the hides remain at rest on the conveyor and the bridge frame is provided with means for its translation stepwise along the longitudinal axis of the conveyor.