The present application is a 35 U.S.C. §§371 national phase conversion of PCT/EP2011/004534, filed Sep. 8, 2011, which claims priority of European Application No. 10010183.1, filed Sep. 22, 2010, the contents of which are incorporated by reference herein. The PCT International Application was published in the French language.
The present invention relates to a machine for processing elements in sheet form, comprising a chainset tensioner.
The invention finds an advantageous, although nonexclusive, application in the field of machines for converting sheets of paper or cardboard for the manufacture of packaging.
A machine for processing elements in sheet form comprises a succession of workstations, possibly including a workstation which comprises a platen press for converting the sheets.
It is in fact common practice to carry out an operation of converting a sheet of paper or of cardboard in a machine for processing elements in sheet form. This may, for example, be a printing operation, including the printing of texts and/or patterns by hot-stamping, that is to say by using pressure to apply a colored or metalized film taken from one or more stamping strips. It may also involve embossing or scoring, which means to say deforming the sheet in order to impress a relief thereon. It may also involve cutting in order to cut the sheet to convert it into one or more copies. In industry, such a conversion operation is usually performed using a vertical platen press into which the sheets are introduced one at a time.
In the example of a machine schematically depicted in
In practice, this is usually a series of transverse bars fitted with grippers 70. These transverse bars, commonly known as gripper bars, each in turn grasp a sheet at its frontal edge, before pulling it in turn into the various workstations of the machine.
The ends of the gripper bars 70 are each respectively connected to a lateral chain forming a loop, commonly known as a chainset 80. Patents EP-B-448 943 and EP-B-680 906 describe in detail exemplary embodiments of gripper bars and chainsets.
Thanks to a movement transmitted to the chainsets 80, all of the gripper bars 70 will start out from a stationary position, will accelerate, will reach a maximum speed, will decelerate and then come to a standstill, thus describing an acceleration and speed cycle corresponding to the transfer of a sheet from one workstation to the next workstation. Each station performs its work in synchrony with this cycle that is commonly known as the machine cycle. The movements, accelerations, speeds, and forces are often represented on a curve corresponding to a machine cycle, with an abscissa value varying between 0° and 360°. An abscissa value on this kind of curve is commonly known as the press angle (AM). The machine schematically depicted in
Vibration phenomena occur along the chainsets 80 and disrupt their dynamic behavior. In order to limit these vibration phenomena, springs are used to act as tensioners for the chainsets 80, applying a force to a guide device in contact with the chain, it being possible for example for the guide device to be a pulley.
With an increase in machine production rates, the gripper bars 70 and the chainsets 80 are subjected to increasingly high mechanical stresses and have therefore to be increasingly strong. The vibrational phenomena are also more violent, and dictate the use of increasingly powerful springs applying increasing tensions, and this further increases the mechanical stresses on the chainsets 80, thereby reducing their service life and increasing the risk of breakdown or breakage. It then becomes necessary to reinforce the chainsets 80, and therefore to increase the power of the driving and braking elements that will accelerate and decelerate them during each cycle.
The technical problem addressed by the subject matter of the invention is therefore that of improving the device for reducing the vibrational phenomena along a chainset. The present invention relates to a machine for processing elements in sheet form, comprising chainsets and at least one tensioner device generating a tension force in said chainsets. According to the invention, the chainset tensioner device comprises a drive member capable of generating a variable force, the intensity of which is dependent on the instantaneous production rate of the machine. Chainset wear is greatly reduced, and the life of said chainsets is lengthened considerably.
This description, which is given by way of nonlimiting example, is intended to provide a better understanding of the substance of the invention and of how it may be embodied. It is given with reference to the attached drawings in which:
a to 5e show graphs of Fv versus AM for various conditions.
It should be understood that throughout this text, the terms “sheet” or “element in sheet form” or even “sheet element” denote very generally any print support in the form of sheets, such as, for example, sheets of cardboard, paper, plastic, etc.
At the feed board 200, the sheets (10) are laid out in a layer directly by the gripper member, which means to say that they are laid one after the other with partial overlap. The whole layer is then driven along toward the platen-type conversion device 300. For that, use is made of a conventional belt-type conveyor system which once again for obvious reasons of clarity has not been depicted. At the end of the layer, the lead sheet is systematically positioned accurately, for example using front and side lays.
In the machine schematically depicted in
Just as in the machine depicted schematically in
The process of processing the sheets in the machine ends at the receiving station 500, the main function of which is to form the converted sheets 10 back into a stack. In the case of the stamping machine depicted in
In a processing machine according to the prior art, the two chainsets 80 experience tension generated by one or more tensioners. This or these tensioners may with equal preference be positioned in the machine along the path of the chainsets 80 and apply a force to the chain guide devices, for example pulleys. The force applied by the tensioner device to the chain guide device is determined preferably by the greatest vibrational phenomena that the chainsets 80 and the gripper bars 70 that they drive experience, that is by the maximum production rate of the machine. When wear of the chainsets 80 downgrades their dynamic behavior, the production rate of the machine has then to be reduced or the power of the tensioner increased. Most often, the tensioner device consists of a spring which works either in traction or in compression. However, the applied force may also be generated by any type of return device, such as a suspended mass for example. The tensioner device also is able to take up any play resulting from chainset wear and expansion.
Just as in the prior art, the tensioner device according to the invention can be situated at any location along the path of the chainsets 80.
According to the invention, the tensioner comprises at least one drive member 51 capable of generating a variable force, the intensity of which is dependent on the instantaneous production rate of the machine. That means that the tensioner is dynamic and adapts the force applied to a guide device constantly according to the production rate of the machine. This is because vibration along the chainsets 80 increases as a function of machine production rate and the tension has to be adjusted accordingly.
To do this, the tensioner device therefore comprises a drive member 51 which will typically be a motor. Although any type of motor can be used, use will advantageously be made of a linear motor. This is because there is a desire to control a force applied by the tensioner device. Now, a conventional motor will be controlled in terms of movement and will entail measurement of the tension in the chainset which will be regulated by closed-loop control, whereas for a linear motor control by current is equivalent to direct control of the force applied by the motor and therefore to direct control of the tension force in the chainsets. As a result, by using a linear motor controlled by current, there is no longer any need to measure the tension in the chainsets 80, which can be regulated using open-loop control.
The tension force in the chainsets 80 will therefore also be a function of the instantaneous production rate of the machine, and this will provide effective protection against vibrational phenomena while at the same time limiting the stresses on the chainsets 80. That makes it possible significantly to slow chain wear and significantly increase chain life.
A dynamic tensioner according to the invention may comprise one drive member per chainset 80 or alternatively, as in the particularly advantageous embodiment depicted in
Moreover, the dynamic tensioner may apply a tension force to the chainsets 80 by compression, that is to say by pushing against the chainsets, or alternatively by traction, that is to say by pulling on the chainsets. Advantageously, the tension force will be applied by traction. This is because, and as has been depicted in
Moreover, a belt 55 can easily collaborate with a block and tackle 56, that is to say with a device comprising pulleys for stepping down the traction force generated by the drive member 51.
In the example of a dynamic tensioner according to the invention that has been schematically depicted in
The two ends of the chain guide devices 90 can be capable of translational movement, but it is particularly advantageous to have just one end 91 capable of translational movement and for the chain guide devices 90 to be connected to an end 96 of a pendular lever 95, the other end 97 of the pendular lever 95 being free to rotate about a pivot pin secured to the frame. This particular embodiment, which has been depicted in
As an option, the tensioner device 50 also comprises at least one return device 65 generating a substantially constant force Fc which is applied to the chain guide devices 90. This is because it is always desirable to generate a minimum tension force in the chainsets 80. This minimum force makes it possible for example to take up play resulting from wearing or expansion of the chainsets 80. As a result, the presence of a return device 65 generating a substantially constant force Fc allows the use of a less powerful drive member 51 and makes it possible to save on the energy consumed by this drive member. In addition, in the event of a breakdown of the drive member 51 or of its control circuit, the machine can still be used, but at a reduced production rate, thanks to this minimal tension force present in the chainsets.
In
The series of
Now, it has been seen that, during a machine cycle, the chainsets 80 are stationary so that the elements 10 in sheet form can be converted in a workstation, and then accelerate to convey the elements 10 in sheet form, then slow down to a standstill when the elements 10 in sheet form are correctly positioned in the next workstation. As a result, the vibrational phenomena within the chainsets 80 vary greatly during a machine cycle. They are zero when the chainsets 80 are stationary, then increase sharply as the chainsets 80 accelerate, then decrease, etc. It is therefore particularly advantageous for the variable force Fv generated by the drive member 51 not only to vary as a function of the instantaneous production rate of the machine, but also to vary as a function of the press angle AM, which varies from 0° to 360° during a machine cycle.
Thus,
c illustrates the fact that the change in variable force Fv generated by the drive member 51 is also dependent on other parameters. The chainsets of the machine corresponding to
d and 5e illustrate the fact that a fine analysis of the vibrational phenomena during a machine cycle may allow the variable force Fv to be made to vary in a more complex manner during the course of a machine cycle, in order to optimize the life of the chainsets 80.
In
It should be noted that in the context of the invention, the idea of a processing machine covers a wide variety of embodiments because of the modular structure of these assemblies. Depending on the number, nature and layout of the workstations used, it is in fact possible to obtain a multitude of different processing machines.
It is also important to emphasize that there are other types of workstations than those already mentioned in the context of the description of the machine. Thoughts for example here turn to cutting stations, copy separation stations, waste ejection stations, stamping strip feed stations, etc. Finally, it must be understood that one and the same processing machine could very well be equipped with several stations of the same type.
Number | Date | Country | Kind |
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10010183 | Sep 2010 | EP | regional |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2011/004534 | 9/8/2011 | WO | 00 | 3/21/2013 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2012/038035 | 3/29/2012 | WO | A |
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3847030 | Grutter | Nov 1974 | A |
4284192 | Taylor | Aug 1981 | A |
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5562279 | Gillieron | Oct 1996 | A |
5641058 | Merten et al. | Jun 1997 | A |
6834228 | Serkh et al. | Dec 2004 | B2 |
6845979 | Chiari et al. | Jan 2005 | B2 |
Number | Date | Country |
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0 448 943 | Oct 1991 | EP |
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1 679 188 | Jul 2006 | EP |
2 179 386 | Nov 1973 | FR |
2005-162466 | Jun 2005 | JP |
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Entry |
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International Search Report dated Dec. 16, 2011 issued in corresponding International application No. PCT/EP2011/004534. |
Korean Office Action mailed Sep. 26, 2014 in corresponding Korean Application No. 2013-7008696, along with an English translation of relevant portions thereof. |
Number | Date | Country | |
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20130187333 A1 | Jul 2013 | US |