EP0803000A1

EP0803000A1 - Needling machine and associated feed control method

Info

Publication number: EP0803000A1
Application number: EP96901383A
Authority: EP
Inventors: Bernard Jourde; François LOUIS; Robert Jean
Original assignee: Asselin SA
Current assignee: Asselin SA
Priority date: 1995-01-12
Filing date: 1996-01-12
Publication date: 1997-10-29
Anticipated expiration: 2016-01-12
Also published as: ES2136386T3; DE69603706T2; EP0803000B1; FR2729404A1; ATE183259T1; CA2210466A1; JPH10512020A; WO1996021763A1; FR2729404B1; US5909883A; DE69603706D1

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.

A needling machine has the function of mechanically consolidating a sheet of fibers from a spreader-lapper or any other system and passing between two perforated steel plates called table and stripper respectively. This layer of fibers is crossed by needles arranged on a support generally designated by the term of needle boards. The stripper is facing the needle board which is driven in an alternating movement. The needles penetrate successively into the stripper, into the ply of fibers and into the table, then carry out a reverse path over a needling period during which the ply of fibers moves by a distance called a step in advance. The plies of fibers are entrained in the needling machine upstream by an introduction device made up of a first pair of rollers and downstream of the needling machine, by an extractor device comprising a second pair of rollers. In traditional needling machines, the movement of the fiber web is intermittent and does not take place until the needles are released from the product.

However, a current development in the design of needling machines consists in increasing the striking rates and the running speeds of the product through the machines, in order to increase their productivity. However, the product to be needled is then subjected to each stop and restarting at excessive and hardly controllable accelerations which can lead to degradation of the product. DE-A-1 660 776 discloses a needling machine comprising introduction means and extraction means driven more or less at the rate of needling by means of a differential transmission coupled to the striking device. This drive mode of the extraction rollers does not allow easy and optimal modulation of the extraction speed depending on the type of needled product and the row of

1 needling machine concerned in a line of machines. The object of the invention is to remedy these drawbacks by proposing a needling machine which is designed to allow modulation of the angular speed of the extraction rollers during each needling period, this modulation being able to be of variable amplitude up to 'upon obtaining zero angular acceleration.

This objective is achieved with a needling machine comprising means for needling, according to a variable striking frequency, a sheet of fibers generally passing between two perforated steel plates a first pair of rollers to introduce the sheet of fibers between the two plates with a speed d substantially constant introduction, a second pair of rollers for extracting the sheet of fibers leaving the plates, means for driving the needling means in a periodic striking movement, control and processing means connected to these means needling drive and electromechanical means to drive the extraction rollers at variable speed.

According to the invention, the electromechanical drive means and the control and processing means cooperate to provide a modulation of the angular speed of the extraction rollers around an average extraction speed, this modulation being of variable amplitude , in synchronism with the periodic movement needling means and at a frequency equal to the striking frequency.

Thus, in a needling machine according to the invention, it becomes possible to provide, thanks to the use of electromechanical means at variable speed, a slowing down of the sheet of fibers during needling, which is not reduced to a simple stop of the advance. In fact, with the present invention, it is no longer a question of stop-start sequences, which limits the acceleration value of the sheet, but of a real modulation of the extraction speed, which will allow increase strike frequencies. In addition, the introduction means are maintained at constant speed while the extraction means are modulated in speed, which has the effect of allowing continuous processing of the sheet of fibers. Furthermore, the adjustment of the extraction speed can be controlled by software, which contributes to a flexibility of use which would be difficult to obtain with the mechanical devices of the prior art. In addition, it becomes possible to easily modify the modulation amplitude, for example as a function of the average extraction speed, in particular to reduce the amplitude when the average extraction speed is increased. For the needling of products having a high stiffness or for needling machines located in the first row of a machine line, the present invention makes it possible to provide for a stopping or at least a slowing down of the extraction means during the needling phase. Thus, the extraction speed during a needling period can be modulated, depending on the type of needled product and the row of the needling machine concerned in a machine line.

It is also possible to achieve a discontinuous advance regime in which the electromechanical rotating means and the control and processing means cooperate to provide, over each striking period, a sequence of stopping the extraction rollers corresponding to a discontinuous advance regime of the fiber web, this stopping sequence substantially coinciding with a needling sequence. In addition, the synchronism with the periodic movement of the needling means can be anticipated or delayed in order to take into account the elasticity and the damping of the textile web and the dynamic characteristics of the drive system. This discontinuous advance regime obtained by modulation of the angular speed is particularly suitable for products having a relatively stiff texture or for being used in first line machines. Outside this discontinuous advance regime, the electromechanical rotating means and the control and processing means cooperate to provide a modulation of the angular speed of the extraction rollers, this modulation comprising a deceleration sequence substantially coinciding with a sequence of needling. In another advantageous version of a needling machine according to the invention, the electromechanical rotating means and the control and processing means also cooperate to provide a modulation of the advance pitch of the sheet of fibers around an average pitch d constant advance at a slightly variable amplitude.

This makes it possible, by varying the actual pitch of the advance of the product around a constant mean pitch, to standardize the distribution of the impacts of the needles in the sheet of fibers. This avoids the appearance of untimely patterns on the needled products for steps required for certain textiles but particularly harmful with regard to the implantation of the needles.

In a preferred embodiment of a needling machine according to the invention, the means electromechanical revolving units are made up of one or more geared motors in position. These gearmotors can include a synchronous motor with self-piloted permanent magnets, or an asynchronous motor with vector flow control, or any other motor technology capable of being implemented within a geared motor. One can also consider for the drive of the extraction rollers the use of motors in direct drive. According to another aspect of the invention, there is provided 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 position control of the extraction rollers of 1 needling machine and an adjustment of their angular speed.

Preferably, the adjustment of the angular speed comprises a modulation around an average angular speed, this modulation having a modulation frequency equal to the striking frequency and being carried out in synchronism with the periodic movement of the needling means so that 1 needling of the sheet of fibers substantially coincides with a phase of slowing down the advance thereof.

In the case of a discontinuous advance regime, the modulation of the angular speed has an amplitude such that the angular speed of the extraction rollers is canceled out during the needling sequence of the sheet of fibers. This method can also comprise an adjustment of the phase shift between the angular speed modulation cycles and the striking cycles.

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

This functionality allows the result of the impacts of the needles on the product to be the sum of several different steps accumulated, which makes it possible to operate at an average step ahead whose textile result could be bad in itself and which would be improved. by this accumulation of steps around this average step. This method using a modulation of the advance step is particularly suitable for needling products for which the visual aspect is important or also for being used in finishing needling machines. Other features and advantages of the invention will appear in the description below. In the accompanying drawings given by way of nonlimiting examples: FIG. 1 is an overall view of a needling machine according to the invention; - Figures 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 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 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 respectively designated by the term table (lower plate) and stripper (upper plate), between which moves a sheet of fibers 2 coming from another machine ( not shown) located upstream of the needling machine 1, for example a spreader-lapper. This sheet of fibers 2 is driven within the needling machine 1 thanks, on the one hand, to introducer means 17 generally comprising a pair of rollers 18, 19 driven at constant speed and located at the head of the needling machine 1, and , on the other hand, to extractor means 10 generally produced in the form of two rollers 15, 16 which are driven by a variable speed drive device 12. The needling machine 1 further comprises a set of needle boards 5 , 6, for example two in number, which are subjected to a reciprocating movement perpendicular to the plane of the table and the stripper by means of an alternative driving device 4 located on the upper part of the needling machine 1 and comprising by example of rod-crank assemblies. During a striking cycle, each board 5, 6 is driven in a vertical downward movement until the needles 8 penetrate into the perforations of the stripper 7, in the fibers of the ply 2 which is then slowed down or even immobilized and in the perforations of the table 8. The movement of the hands continues by a rise out of the sheet of fibers 2. This sheet is subjected to a sequential displacement defined by a step of advance which is the distance traveled between two sequences needling. The extraction rollers 15, 16 are driven by an electromechanical device with variable speed 12 comprising a geared motor assembly 124, and an electronic power variator 120. The device electromechanical device 12 is controlled by a control and processing unit 11, associated with usual interface means 13 such as a display monitor and a keyboard, this unit 11 also driving the alternative drive device 4. The assembly geared motor comprises an electric motor 121 and a mechanical reducer 124 intended to adapt the usual nominal speeds of an electric motor to the low speeds required for driving the extraction rollers 15, 16. These extraction rollers must be slaved to the both in speed and in position, which in practice requires the use of position coding means 14 which are connected to the electronic variator to provide this variator with information on the instantaneous position of the rollers. When a permanent magnet synchronous motor or an asynchronous motor with vector flow control are used, then now conventional and widely disclosed autopilot techniques are implemented. We will now describe a first advance control mode implemented in a needling machine according to the invention such as the aforementioned needle 1, with reference to Figures 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 strike cycle according to a modulation waveform 20, 21, for example a sinusoidal 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 a limit frequency, the variable speed waveform 20 can be adjusted so that the speed angular cancels, which corresponds to a stop of the extraction rollers and therefore a discontinuous advance. When the striking frequency is greater than this limiting frequency, it is no longer possible to achieve the cancellation of the angular speed ω and we are then in periodic slowdown regime 21. The lower part of the form of modulation wave 20, 21 corresponds to a needling zone 22 during which the needles 8 penetrate the fiber sheet 2. The striking frequency limits between the discontinuous advance speed and the slowdown speed depends on the maximum acceleration that can be obtained by the gearmotor 124, which itself depends on the inertia of all the mechanical parts driven, the reduction ratio and the maximum torque of the motor. Furthermore, it is also possible to define a limit average advance speed beyond which, for a given striking frequency, it is no longer possible to obtain a discontinuous advance regime. Thanks to the flexibility of control offered by the use of an electronic variator and a variable speed motor, it becomes possible to precisely control the phase difference between the striking or needling cycle and the modulation cycle of the forward speed. In fact, the control and processing unit 11 can be programmed to synchronize the two cycles and predetermine either an advance (FIG. 2B) or a delay (FIG. 2C) of the modulation cycle relative to the typing cycle. In the first case (2B), the needles 8 penetrate the stripper and the fiber web with a delay time τ ^ 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 order is suitable for textured products relatively steep, 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 relative 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 advance control mode which 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 processing unit 11 controls the electromechanical drive device 12 so as to obtain a modulation 30 of the advance step P of the needling machine 1 around a constant average advance step Pm. The modulation period is in practice chosen to be equal to a large number k of striking or needling periods Ta, with the aim of standardizing the distribution of the impacts of the needles on the sheet of fibers. The striking sequence F comprises elementary striking cycles corresponding to an alternation of high positions H of the needle boards and low needling positions A. For a given striking frequency, the step of advance? is directly proportional to the average speed of advance and therefore to the average speed of rotation of the extraction rollers which can be adjusted without difficulty in a needling machine according to the invention.

It is also possible to combine the control modes which have just been described, as illustrated in FIG. 4B. The angular speed ω then has a double modulation: a first modulation 40 is performed at a first modulation frequency equal to the striking frequency (period Ta) and corresponds to a cyclic slowdown or stop synchronous with the needling, while a second modulation 31 affects the average angular velocity and corresponds to a second modulation frequency generally very low compared to the striking frequency and equal to the modulation frequency of the advance pitch P around the average pitch Pm.

Of course, the invention is not limited to the examples which have just been described and numerous modifications can be made to these examples without departing from the scope of the invention. Thus, the extraction rollers can be driven by any type of motor or gearmotor without any conceptual limitation other than the need for sufficient performance in terms of torque / inertia ratio. One can thus envisage a drive by variable reluctance motors or also hybrid motors. Furthermore, mechanical devices can also be provided for indirectly driving the extraction rollers from a single geared motor. The modulation profiles can be adapted to the products to be needled, to the rates sought and to the type of needling selected.

Claims

Rsvand πar.innς 1. Needling machine (1) comprising means (6, 5) for needling according to a variable striking frequency a sheet of fibers (2) generally passing between two perforated steel plates (7, 3), a first pair of rollers (18, 19) for introducing the fiber web (2) between the two plates (7, 3) with a substantially constant insertion speed, a second pair of rollers (15, 16) for extracting the web of fibers (2) at the outlet of the plates (7, 3), means (4) for driving the needling means (5, 6) in a periodic striking movement, control and treatment means (11, 13) connected to these needling drive means (4), electromechanical means (12) for driving the extraction rollers (15, 16) at variable speed, characterized in that the electromechanical drive means (12) and the control and processing means (11) cooperate to provide modulation of the angular speed of s extraction rollers (15, 16) around an average extraction speed, this modulation being of variable amplitude, in synchronism with the periodic movement of the needling means (5, 6) and at a frequency equal to strike frequency.

2. Needling machine (1) according to claim 1, characterized in that the electromechanical means (12) and the control and treatment means (11) cooperate to provide, during each striking period, a sequence of stopping the extraction rollers (15, 16) corresponding to a discontinuous advance regime of the fiber web (2), this stop sequence substantially coinciding with a needling sequence.

3. Needling machine (1) according to claim 2, characterized in that the discontinuous advance speed corresponds either to a striking frequency less than a limiting striking frequency for a given average advance speed, or to a speed of average advance lower than a limit advance speed for a given striking frequency.

4. Needling machine (1) according to claim 3, characterized in that for a striking frequency and s an average advance speed not corresponding to a discontinuous advance speed, the electromechanical rotating means (12) and the control means and processing (11) cooperate to provide a modulation of the angular speed of the extraction rollers (15, 16), this modulation comprising a slowing sequence substantially coinciding with a needling sequence.

5. Needling machine (1) according to one of the preceding claims, characterized in that the modulation of the angular speed is substantially sinusoidal.

6. Needling machine (1) according to one of the preceding claims, characterized in that the rotating electromechanical means (12) and the control and processing means (11) also cooperate to provide a modulation of the advance step (P ) of the sheet of fibers (2) around an average advance pitch (Pm) according to a modulation frequency submultiple of the striking frequency.

7. Needling machine (1) according to claim 6, characterized in that the modulation of the advance step (P) is substantially sinusoidal.

8. Needling machine (1) according to one of the preceding claims, characterized in that the electromechanical means (12) comprise electronic converter means (120) and gearmotor means (121, 123) controlled in position.

9. Needling machine (1) according to claim 8, characterized in that the geared motor means (12 ⁾ comprise a synchronous motor with permanent self-piloting magnets (121).

10. Needling machine (1) according to claim 8, characterized in that the geared motor means ⁽ 12 ⁾ comprise an asynchronous motor with squirrel cage (121 ⁾ .

11. Needling machine (1) according to claim 10, characterized in that the electromechanical means (12) are arranged to provide a vector control mode of the asynchronous motor (121).

12. Needling machine (1) according to one of claims 1 to 7, characterized in that the electromechanical means (12) comprise motors directly engaged on the extraction rollers (15, 16).

13. Method for controlling the advance of a sheet of fibers (2) in a needling machine (1) according to one of the preceding claims, characterized in that it comprises a position control of the extraction rollers (15, 16) of the needling machine (1) and an adjustment of their angular speed by the electromechanical drive means (12) and the control and processing means (11).

14. Method according to claim 13, characterized in that the adjustment of the angular speed comprises a modulation around an average angular speed, this modulation having a modulation frequency equal to the striking frequency and being carried out in synchronism with the movement periodical needling means (5, 6) so that 1 needling of the fiber web (2) coincides substantially with a phase of slowing the advance thereof.

15. The method of claim 14, characterized in that the modulation of the angular speed has an amplitude such that the angular speed of the extraction rollers (15, 16) is canceled during the needling sequence of the sheet of fibers (2).

16. Method according to one of claims 14 or 15, characterized in that it further comprises an adjustment of the phase shift between the cycles of modulation of the angular speed and the striking cycles.

17. Method according to one of claims 13 to 16, characterized in that it further comprises a modulation of the advance σas (P) of the sheet of fibers (2) around a mean feed step (Pm), this modulation being carried out at a pitch modulation frequency sub-multiple of the punching machine strike frequency.

18. The method as claimed in claim 17, characterized in that it further comprises a double modulation of the angular speed of the extraction rollers comprising a first modulation at the striking frequency around an average angular speed and a second modulation, at the pitch modulation frequency, this average angular velocity.