EP0803000B1 - Needling machine and associated feed control method - Google Patents

Abstract

PCT No. PCT/FR96/00052 Sec. 371 Date Aug. 11, 1997 Sec. 102(e) Date Aug. 11, 1997 PCT Filed Jan. 12, 1996 PCT Pub. No. WO96/21763 PCT Pub. Date Jul. 18, 1996A needling machine for the fabrication of non woven products includes apparatus for needling a lap passing between two perforated steel plates, and introducing mechanism for introducing the fiber lap between the two plates, an extractor for extracting the lap downstream of the needling apparatus, a drive source for driving the needling apparatus with a periodical-striking motion, and a processing and control device connected to the needling drive source. The needling machine further includes an electromechanical speed control for driving at a variable speed the extractor, controlled by the processing and control device to provide the extraction means with an extraction speed modulated to the striking frequency at about an average extraction speed.

Description

The present invention relates to a needling machine and an associated advance control method.

The purpose of a needling machine is to consolidate mechanically a sheet of fibers from a spreader-lapper or any other system and passing between two perforated steel plates called table respectively and stripper. This layer of fibers is crossed by needles generally placed on a support referred to as needle boards. The stripper stands opposite the plank hands which is driven in an alternating movement. The needles successively enter the stripper, in the fiber sheet and in the table, then perform a reverse route over a needling period during from which the fiber web moves a distance called not in advance. The fiber layers are driven in the needling machine upstream by a introducer consisting of a first pair rollers and downstream of the needling machine, by a extractor device comprising a second pair of rollers.

In traditional needling machines, the movement of the fiber web is intermittent and only takes place when the needles are released from the product.

However, a current development in the design of needling machines consists in increasing the rates of strikes and product scrolling speeds through machines to increase productivity. But the product to be needled is then subjected to each stop and restarting at excessive accelerations and difficult to control which can lead to degradation of the product.

We know from DE-A-1 660 776 a needle loom comprising introduction means and means of extraction driven more or less at the rate of needling using differential transmission coupled to the striking device. This mode of training extraction rollers do not allow modulation easy and optimal extraction speed depending the type of needled product and the rank of the needling machine concerned in a line of machines.

The object of the invention is to remedy these disadvantages of offering a needle loom that is designed to allow speed modulation angle of the extraction rollers during each needling period, this modulation can be of variable amplitude until a zero angular acceleration.

This objective is achieved with a needling machine comprising means for switching according to a variable strike frequency a passing sheet of fibers usually between two perforated steel plates one first pair of rollers to introduce the sheet of fibers between the two plates with a speed of substantially constant introduction, a second pair rollers to extract the sheet of fibers at the outlet plates, means for training the means needling in a periodic striking movement, control and processing means related to these needling drive means and means electromechanical to drive variable speed extraction rollers.

According to the invention, the electromechanical means training and means of control and treatment cooperate to provide speed modulation angle of the extraction rollers around a speed average extraction, this modulation being of amplitude variable, in synchronism with the periodic movement needling means and at a frequency equal to the strike frequency.

Thus, in a needling machine according to the invention, it becomes possible to predict, thanks to the implementation of electromechanical means with variable speed, one slowing of the sheet of fibers during needling, which cannot be reduced to a simple stop in advance. Indeed, with the present invention, it does not more then stop-start sequences, which limits the acceleration value of the water table, but by real modulation of the extraction speed, which goes allow to increase the striking frequencies. Moreover, the introduction means are kept at speed constant while the extraction means are modulated in speed, which has the effect of allowing a continuous treatment of the fiber web. Otherwise, the setting of the extraction speed can be controlled by software, which contributes to flexibility of use that would be difficult to obtain with mechanical devices of the prior art. Furthermore, it becomes possible to easily change the amplitude of modulation, for example as a function of average speed extraction, in particular to reduce the amplitude when the average extraction speed is increased.

For needling products with high stiffness or for needles located in the first row of a line of machines, the present invention makes it possible to provide for a stop or at least a slowdown in resources extraction during the needling phase. So the extraction speed during a period needling can be adjusted, depending on the type of needled product and needler row concerned in a line of machines.

One can also reach a scheme in advance discontinuous in which the electromechanical means and the means of control and treatment cooperate to provide each strike period corresponding extraction roller stop sequence at a discontinuous advance rate of the fiber web, this stopping sequence substantially coinciding with a needling sequence.

In addition, the synchronism with the movement needling can be anticipated or delayed to account for elasticity and amortization of the textile web and dynamic characteristics of the drive system.

This discontinuous advance scheme obtained by modulation angular velocity is particularly suitable for products with a relatively stiff texture or to be used in the first machines of line.

Outside of this discontinuous advance scheme, the means electromechanical rotating and control means and co-operate to provide modulation of the angular speed of the extraction rollers, this modulation with a deceleration sequence substantially coinciding with a needling sequence.

In another advantageous version of a needling machine according to the invention, the means electromechanical rotating and control means and further cooperate to provide a modulation of the advance step of the layer of fibers around of a constant average step of advance according to an amplitude slightly variable.

This allows, by varying the real step of product advance around a constant average pitch, standardize the distribution of needle impacts in the fiber sheet. This avoids the appearance of untimely patterns on needle punched products for no advance required for certain textiles but particularly detrimental with regard to implantation of needles.

In a preferred embodiment of a needling machine according to the invention, the means electromechanical revolving devices consist of one or several geared motors slaved in position. These gearmotors can include a synchronous motor to permanent autopilot magnets, or a motor asynchronous with vector flow control, or any other engine technology that may be used implemented within a geared motor. We can also consider for the drive of the extraction rollers the use of direct drive motors.

According to another aspect of the invention, it is proposed a method for controlling the advance of a sheet of fibers in a needling machine according to the invention, characterized in that it comprises a servo of position of the needle roller and an adjustment of their angular speed.

Preferably, the angular speed adjustment includes modulation around an angular speed medium, this modulation having a frequency of modulation equal to the strike frequency and being performed in synchronism with the periodic movement of needling means so that the needling of the fiber sheet substantially coincides with a phase of slowing down of the advance thereof.

In the case of a discontinuous advance scheme, the angular velocity modulation has an amplitude such as the angular speed of the extraction rollers cancels during the tablecloth needling sequence fiber. The method may further include adjusting the phase difference between the speed modulation cycles angular and typing cycles.

According to yet another aspect of the invention, it a method is proposed for ordering the advance of a needling machine according to the invention, characterized in that it further includes modulation of the advance step of the sheet of fibers around an average pitch, this modulation being performed at a submultiple frequency the frequency of the needling machine. This process can be combined with the above process and thus include a angular speed modulation.

This feature allows the result of impacts of the needles on the product, i.e. the sum of several different steps combined, which allows operate at an average step ahead, the result textile could be bad in itself and that would would find improved by this accumulation of steps around this step way.

This method implementing a modulation of the pitch in advance is particularly suitable for needling products for which the visual aspect is important or still to be used in needle looms finish.

• la figure 1 est une vue d'ensemble d'une aiguilleteuse selon l'invention;
• les figures 2A, 2B et 2C représentent respectivement l'évolution temporelle de la vitesse angulaire des rouleaux d'extraction en régime de modulation de vitesse, une première situation de déphasage avant des cycles de frappe par rapport aux cycles de ralentissement et une seconde situation de déphasage arrière des cycles de frappe par rapport aux cycles de ralentissement;
• les figures 3A et 3B illustrent respectivement une modulation du pas d'avance et des cycles de frappe correspondant à cette modulation; et
• la figure 4 illustre la combinaison d'une modulation du pas d'avance et d'une modulation de la vitesse angulaire avec avance discontinue qui permet d'améliorer l'aspect fini du produit par cumul de pas différents autour de la valeur moyenne.

Other features and advantages of the invention will become apparent in the description below. In the appended drawings given by way of nonlimiting examples:

• Figure 1 is an overall view of a needling machine according to the invention;
• FIGS. 2A, 2B and 2C respectively represent the time evolution of the angular speed of the extraction rollers in speed modulation mode, a first phase shift situation before the striking cycles with respect to the deceleration cycles and a second situation of rear phase shift of the striking cycles with respect to the deceleration cycles;
• FIGS. 3A and 3B respectively illustrate a modulation of the advance step and of the striking cycles corresponding to this modulation; and
• FIG. 4 illustrates the combination of a modulation of the advance step and a modulation of the angular speed with discontinuous advance which makes it possible to improve the finished appearance of the product by cumulation of different steps around the average value.

We will now describe an example of an embodiment of a needling machine according to the invention at the same time as the advance control method implemented in this needling machine.

A needling machine 1 according to the invention comprises two perforated parallel plates 3, 7 designated respectively under the term table (bottom plate) and stripper (upper plate), between which moves a sheet of fibers 2 from another machine (not shown) located upstream of the needling machine 1, for example a spreader-lapper. This layer of fibers 2 is driven within the needling machine 1 thanks to a part, to introducer means 17 comprising generally a pair of rollers 18, 19 driven constant speed and located at the head of the needling machine 1, and, on the other hand, to extractor means 10 produced generally in the form of two rollers 15, 16 which are driven by a speed drive variable 12. The needling machine 1 further comprises a set of needle boards 5, 6, for example at number of two, which are subject to movement alternative perpendicular to the plane of the table and stripper by means of a drive device alternative 4 located on the upper part of the needling machine 1 and comprising for example assemblies crank rod. During a typing cycle, each plate 5, 6 is driven in a vertical movement descending until needles 8 enter the perforations of the stripper 7, in the fibers of the tablecloth 2 which is then slowed down or even immobilized and in the perforations of the table 8. The movement of needles continues with a rise out of the water table of fibers 2. This sheet is subject to displacement sequential defined by a step ahead which is the distance traveled between two needling sequences. The extraction rollers 15, 16 are driven by a electromechanical variable speed device 12 comprising a geared motor assembly 124, and a variator 120 power electronics. The device electromechanical 12 is controlled by a control unit and processing 11, associated with interface means usual 13 such as a display monitor and a keyboard, this unit 11 also controlling the device alternative drive 4. The gearmotor assembly includes an electric motor 121 and a reduction gear mechanical 124 intended to adapt the nominal speeds common of an electric motor at low speeds required for driving the extraction rollers 15, 16. These extraction rollers must be slaved to both in speed and in position, which requires practice the use of position coding means 14 which are connected to the electronic dimmer to provide this variator information on the instantaneous position rollers. When a synchronous magnet motor permanent or asynchronous flow control motor vectorial are used, we then implement now classic and widely disclosed techniques autopilot.

We will now describe a first advance control mode implemented in a needling machine according to the invention such as the above-mentioned needling machine 1, with reference to FIGS. 2A to 2C. In this first mode, it is assumed that the advance step and the striking frequency are kept constant during the operation of the needling machine. The instantaneous angular speed ω of the extraction rollers 15, 16 is modulated on each striking cycle according to a modulation waveform 20, 21, for example a sine waveform, around an average angular speed ω _m . This average angular speed must be chosen with respect to the speed of introduction so that it corresponds to an average flow of product extracted equal to the average flow of product introduced.

For a strike frequency lower than one frequency limit, you can adjust the waveform of variable speed 20 so that the speed angular is canceled, which corresponds to a stop of the extraction rollers and therefore a discontinuous feed. When the strike frequency is higher than this frequency limit, it is no longer possible reach the cancellation of the angular speed ω and we is then in periodic slowdown regime 21. The lower part of the modulation waveform 20, 21 corresponds to a needling zone 22 during from which the needles 8 penetrate into the sheet of fibers 2. The strike frequency limits between the regime discontinuous feed and slowdown depends on the maximum acceleration that the geared motor 124, which itself depends on the inertia of all driven mechanical parts, from the report reduction and maximum engine torque. Through elsewhere, we can also define a speed of advance mean limit beyond which, for a frequency of given strike, it is no longer possible to obtain a diet discontinuous advance.

Thanks to the flexibility of control offered by the use of an electronic variator and a motor with variable speed, it becomes possible to order with precision the phase difference between the striking cycle or and the speed modulation cycle in advance. Indeed, one can program the unit of control and processing 11 to synchronize the two cycles and predetermine either an advance (Figure 2B), either a delay (FIG. 2C) of the modulation cycle by compared to the typing cycle.

In the first case (2B), the needles 8 penetrate the stripper and the fiber sheet with a delay time τ _b while the extraction rollers are already stopped or have exceeded their point of maximum deceleration. During the withdrawal of the needles, the extraction rollers are again driven. This type of control is suitable for products with a relatively stiff texture implying needle penetration at zero or very low feed speed.

In the second case (2C), the needles 8 penetrate into the stripper and into the fiber web with a time of advance τ _c with respect to the instant of stop or maximum deceleration of the extraction rollers. This advance allows withdrawal of the needles at very low speed of movement of the sheet of fibers.

We will now describe a second control mode in advance can be implemented in a needling machine according to the invention, with reference to the figures 3A and 3B. In this second mode, the control and treatment 11 controls the drive device electromechanical 12 so as to obtain a modulation 30 of the step P of the needling machine 1 around a step constant mean advance Pm. The modulation period is in practice chosen equal to a high number k of periods typing or needling Ta, in order to standardize the distribution of needle impacts on the water table fibers. Typing sequence F includes cycles elementary strikes corresponding to an alternation of high positions H of the needle boards and low needling positions A. For a frequency of given strike, the advance step P is directly proportional to the average speed of advance and therefore to the average speed of rotation of the extraction rollers which can be easily adjusted in a needling machine according to the invention.

We can also plan to combine the modes of command just described, as illustrated in the figure 4. The angular speed ω then presents a double modulation: a first modulation 40 is performed at a first modulation frequency equal to the strike frequency (period Ta) and corresponds to a synchronous slowdown or cyclic stop with needling, while a second modulation 31 affects the average angular velocity and corresponds to a second modulation frequency generally very low in front of the striking frequency and equal to the frequency of modulation of the advance step P around the average step Pm.

Of course, the invention is not limited to the examples which have just been described and numerous arrangements can be brought to these examples without departing from the framework of the invention. Thus, the extraction rollers can be driven by any type of engine or geared motor without any other conceptual limitation that the need for sufficient performance in terms of torque / inertia ratio. We can thus consider driving by reluctance motors variable or hybrid motors. We also may also provide mechanical devices indirect drive of the extraction rollers from a single geared motor. The profiles of modulation can be adapted to the products to switch, at the required rates and type needling machine selected.

Claims (18)

1. Needling machine (1) comprising means (6, 5) for needling, according to a variable striking frequency, a fibre fleece (2) generally passing between two perforated steel plates (7, 3), a first pair of rollers (18, 19) for inserting the fibre fleece (2) between the two plates (7, 3) with an approximately constant insertion speed, a second pair of rollers (15, 16) for extracting the fibre fleece (2) emerging from the plates (7, 3), means (4) for driving the needling means (5, 6) with a periodic striking motion, means for driving the extraction rollers (15, 16) at a speed modulated about an average extraction speed, this modulation being of variable amplitude, in synchronism with the periodic motion of the needling means (5, 6) and at a frequency equal to the striking frequency, characterised in that the means for driving the extraction rollers comprise electromechanical means (12) controlled by control and processing means (11) also controlling the means (4) for driving the needling means (5, 6).
2. Needling machine (1) according to Claim 1, characterised in that the electromechanical means (12) and the control and processing means (11) cooperate in order to produce in each striking period a stopping sequence of the extraction rollers (15, 16) corresponding to discontinuous feed conditions of the fibre fleece (2), this stopping sequence substantially coinciding with a needling sequence.
3. Needling machine (1) according to Claim 2, characterised in that the discontinuous feed conditions correspond either to a striking frequency lower than a limit striking frequency for a given average feed speed, or to an average feed speed lower than a limit feed speed for a given striking frequency.
4. Needling machine (1) according to Claim 3, characterised in that for an average striking frequency and feed frequency not corresponding to discontinuous feed conditions, the rotating electromechanical means (12) and the control and processing means (11) cooperate in order to procure a modulation of the angular velocity of the extraction rollers (15, 16), this modulation comprising a slowing down sequence substantially coinciding with a needling sequence.
5. Needling machine (1) according to one of the preceding claims, characterised in that the modulation of the angular velocity is substantially sinusoidal.
6. Needling machine (1) according to one of the preceding claims, characterised in that the rotating electromechanical means (12) and the control and processing means (11) cooperate in order to procure a modulation of the feed step (P) of the fibre fleece (2) about an average feed step (Pm) according to a modulation frequency which is a sub-multiple of the striking frequency.
7. Needling machine (1) according to Claim 6, characterised in that the modulation of the feed step (P) is substantially sinusoidal.
8. Needling machine (1) according to one of the preceding claims, characterised in that the electromechanical means (12) comprise electronic converter means (120) and motor-reduction means (121, 123) which are servo-controlled in position.
9. Needling machine (1) according to Claim 8, characterised in that the motor-reduction means (12) comprise a self-controlled synchronous motor with permanent magnets (121).
10. Needling machine (1) according to Claim 8, characterised in that the motor-reduction means (12) comprise an asynchronous squirrel-cage motor (121).
11. Needling machine (1) according to Claim 10, characterised in that the electromechanical means (12) are arranged to procure a vector control mode of the asynchronous motor (121).
12. Needling machine (1) according to one of Claims 1 to 7, characterised in that the electromechanical means (12) comprise direct drive motors for driving the extraction rollers (15, 16).
13. Method for controlling the feed of a fibre fleece (2) in a needling machine (1) according to one of the preceding claims, characterised in that it comprises a servo-control of the position of the extraction rollers (15, 16) of the needling machine (1) and an adjustment of their angular velocity by the electromechanical drive means (12) and the control and processing means (11).
14. Method according to Claim 13, characterised in that the adjustment of the angular velocity comprises a modulation about an average angular velocity, this modulation having a modulation frequency equal to the striking frequency and being carried out in synchronism with the periodic motion of the needling means (5, 6) such that the needling of the fibre fleece (2) substantially coincides with a slowing down phase of the feed of the latter.
15. Method according to Claim 14, characterised in that the modulation of the angular velocity has an amplitude such that the angular velocity of the extraction rollers (15, 16) is eliminated during the needling sequence of the fibre fleece (2).
16. Method according to one of Claims 14 or 15, characterised in that it furthermore comprises an adjustment of the phase shift between the angular velocity modulation cycles and the striking cycles.
17. Method according to one of Claims 13 to 16, characterised in that it furthermore comprises a modulation of the feed step (P) of the fibre fleece (2) about an average feed step (Pm), this modulation being carried out at a step modulation frequency which is a sub-multiple of the striking frequency of the needling machine.
18. Method according to Claim 17, characterised in that it furthermore comprises a double modulation of the angular velocity of the extraction rollers comprising a first modulation at the striking frequency about an average angular velocity and a second modulation, at the step modulation frequency, of this average angular velocity.

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