The present invention pertains to a device for applying glue onto a book block.
Book blocks typically consist of gathered folded sections and/or single sheets that are moved past a gluing device in a transport mechanism, particularly for applying glue onto the book block spine. The gluing device features a glue basin, at least one application roller that dips into the glue basin and rolls on the book block with its circumference, and a scraper that can be adjusted with respect to its distance from the application roller and thusly defines the thickness of the glue layer to be transferred onto the book block.
In the manufacture of bookbinding end products that feature a book block, the book block is initially gathered from individual folded sections and/or single sheets, then processed on the book block spine with milling tools or sewn and subsequently connected with glue, wherein a cover or a lining may, if applicable, also be glued to the book block spine. In order to apply the glue, the book block is laterally clamped in a transport mechanism such that the block spine protrudes downward and moved past a stationary glue application device along the spine.
There exist roller-type gluing stations [see Industrielle Buchbinderei; Dieter Liebau, Inés Heinze; 2nd Edition 2001, Beruf+Schule Publishing, ltzehoe; Page 284 f.] with two successively arranged application rollers that dip into a glue basin, wherein these application rollers roll on the book block spine due to their rotation in the same direction as the block transport direction and transfer the glue onto the spine during this process. The glue quantity or the thickness of the glue layer being applied is defined by a scraper that can be adjusted with respect to its distance from the application roller. An application length can be defined by closing and opening this transport gap accordingly. To this end, different scraper controls have been disclosed, in which the scraper is arranged on a pivoted scraper shaft that features a lever on its end.
It is known to realize the control by means of rotationally driven cam plates that act upon the lever. In order to change the application position, particularly the application length, the cam plates need to be adjusted relative to one another and relative to the machine cycle. Differential gears that can be actuated manually or with servomotors are provided for this purpose. Radial cams have the disadvantage that they cannot be realized with the gradient required for a steep change of the glue layer thickness on the application roller.
In DE 10242260 A1, the scraper shafts are driven pneumatically by means of contraction hoses that shorten under pressure. A defined opening gap can be adjusted by varying the pressure. According to DE 10242259 A1, the scraper shafts are driven by means of piezo-ceramic actuators.
In the scraper control according to EP 1 208 998 B1, the pivoted scraper shaft is directly connected to and driven by a driving element of a controllable electric motor. This makes it possible to vary the application position, application length and application thickness by means of the machine control. In EP 1 873 964 A1, the lever of the scraper shaft is positively connected to a radial cam connected to and driven by a motor. A desired distance of the scraper from the application roller can be adjusted by turning the cam plate within a working range.
Pivoted scraper shafts have the disadvantage that they restrict the constructive design options of the movement to and from the application roller, particularly of the path of the scraper toward the application roller. The transfer of the drive or control movement to the pivoting scraper shaft is particularly complicated with linearly acting drives because additional transmission and/or coupling elements are required. It is also disadvantageous that the scraper shafts only carry out relatively short forward and backward pivoting movements in rapid succession such that the pivot bearings can quickly wear out and the desired distance of the scraper from the application roller can no longer be exactly adjusted. Bearings and/or slideways on the gluing station, whether linear or rotative, are furthermore subjected to significant soiling with overflowing glue, glue vapors and condensates, as well as paper dust, such that the smooth running and the service life of the bearings are additionally diminished.
The present invention is based on the objective of providing a device for applying glue in which the design options of the scraper movement are expanded and an exact and reliable adjustment of the scraper can be realized with a simple construction.
This objective is attained in that the scraper is arranged or realized on a coupler of an at least four-bar coupling or guiding mechanism. The point path or trajectory of the scraper edge defining the distance from the application roller can be designed arbitrarily by realizing the coupling mechanism accordingly, e.g., with respect to the rigid frame bearings and the dimensions of the elements of mechanism. This makes it possible, for example, to realize a radial movement to and from the application roller. The coupling movement may be realized linearly, translatory or rotatory or in the form of a combination of these movements.
The coupling mechanism preferably features grounded links that are realized in the form of bending rods, both ends of which are firmly clamped in place, such that wear-prone (pivot) bearings and/or slideways are eliminated. The robust guiding mechanism is tolerant to soiling and therefore safe from any type of contamination or soiling. The bending rods may also stand in the glue basin. It is possible to utilize bending rods because the scraper only needs to be moved with a relatively short stroke such that only small excursions of the bending rods are required.
According to one preferred additional development, the bending rods are realized in the form of leaf springs that are arranged parallel to the axis of the application roller with their leaf surface. This arrangement results in a high torsional stiffness about the two axes that respectively lie transverse to the rotational axis of the application roller such that the scraper edge always extends parallel to the application roller.
The coupling mechanism is preferably realized in the form of a parallel rod mechanism with grounded links of equal length such that a purely translatory movement of the coupler or the scraper takes place. If the coupling mechanism is used in the region of the summit of the coupling movement, an essentially linear movement of the coupler or scraper is achieved.
According to one preferred additional development, the coupling mechanism is arranged outside the glue basin, wherein the coupler or scraper is realized such that it protrudes transverse to the plane of movement and supported by at least one additional grounded link or a congruent coupling mechanism on its end. The glue basin is freely accessible and only traversed by the scraper. The coupling mechanism with the scraper preferably is rigidly arranged on a removable glue basin.
The distance of the scraper from the application roller can be easily controlled with the direct drive of the coupler. Motor-driven radial cams or pneumatic or electric actuators may be used. The driving power is directly transmitted to the scraper rather than by means of grounded links, couplers and/or levers that are afflicted with elasticity and/or play.
In order to control the distance of the scraper from the application roller, the coupler is preferably driven by at least one gearless, linear electric direct drive. This makes it possible to change the application position, application length and application thickness by means of the machine control. Due to the short stroke of the coupler, one component of the direct drive may be arranged stationarily. The occurring changes in parallelism and the distance of the two components relative to one another are minimal and lie within the tolerance of the contactless direct drive.
A constructively simple variation is achieved if the secondary component of the direct drive with the permanent magnets is arranged or realized on the coupler. This eliminates the need to install any connecting lines on the moving coupler.
The primary component with the electric excitation coils preferably is stationarily arranged on the side of the coupler that lies opposite of the grounded links. The magnetic forces of attraction between the primary and the secondary component of the direct drive do not subject the grounded links to buckling stresses, but rather to tensile stresses, such that a constructively simple and therefore more dynamic coupling or guiding mechanism can be realized.
In another embodiment, the primary component is arranged on a receptacle device for the removable glue basin that features the coupling mechanism. When the glue basin is removed, the contactless direct drive is separated and the functional surfaces of both components are accessible for inspection and cleaning purposes. When using glue basins that can be alternately inserted, only a single hard-wired primary component with the electric excitation coils is required while one respective coupling mechanism with the secondary component featuring the permanent magnets is arranged on the alternately used glue basins.
When the direct drive is switched off, it is advantageous that the scraper is in a neutral position, in which the scraper has a definable distance from the application roller. This distance may also be equal to zero. This simplifies the exchange of the glue basins and a fail-safe state is achieved in case the direct drive fails.
It is advantageous to carry out a calibration process, in which the zero position for completely scraping the glue off the application roller can be defined. This makes it possible to automatically compensate the wear of the scraper edge.
Exemplary embodiments of the inventive device are described in greater detail below with reference to the drawing, in which:
The gluing station 1 includes two successively arranged application rollers 5 that rotate in the same direction as the transport direction F. They dip into a basin 4 that is filled with glue 3, pick up glue 3 with their outer surface and trans-fer the glue 3 onto the book block spine 2a in the form of a rolling movement. A thin glue layer is applied with the first application roller 5.1. The glue application for stabilizing the book block spine 2a is realized by applying a thicker glue layer with the second application roller 5.2. The applied glue layer is ultimately smoothed out by means of a spinner 9 that rotates in the opposite direction.
The respective glue layers 8.1 and 8.2 to be transferred onto the book block spine 2a are defined by a scraper 7 that can be adjusted with respect to its distance s from the application roller 5. Excess glue 3 is scraped off the application roller 5 by the scraper 7 and flows back into the basin 4. An application length can be defined by closing and opening this transport gap accordingly. This is necessary in order to prevent glue from being applied onto the end regions at the head and the foot of the book block spine 2a.
The actuation of the scraper 7 is realized with a scraper device 6 (see also
The coupling mechanism 20 is realized in the form of a parallel rod mechanism with grounded links 22, 23 of equal length. Consequently, the coupler 24 and the scraper 7 respectively carry out a purely translatory movement, wherein the relatively short stroke of the scraper 7 that amounts to only a few millimeters essentially extends linearly in the region of the summit of the coupling movement. This makes it possible to directly actuate the coupler 24 with the linear motor 30 or, alternatively, with a moving coil 50 (see below).
According to
The linear motor 30 directly drives the coupler 24 and therefore the scraper 7. The primary component 31 is rigidly fixed on the frame and the secondary component 32 is arranged on the coupler 24. In this case, the primary motor component 31 with the hard-wired electric excitation coils is situated on a receptacle device 10 for the gluing station 1 while the coupling mechanism 20 with the permanent magnets of the secondary component 32 glued onto the coupler 24 is situated on the removable glue basin 4.
A position measuring system including a position sensor 33 and a measuring scale 34 is operatively connected to the linear drive 30. It is controlled by a drive control 35 that communicates with the machine control 36. The respective scraper 7 is initially closed (distance s is equal to zero). When a book block 2 approaches the application roller 5, the scraper 7 is opened by a definable distance s in dependence on the transport movement such that the applied glue layer begins at a definable distance from the front book block edge on the book block spine 2a. The scraper is accordingly closed once again when the rear book block edge reaches the application roller 5 such that the glue layer also ends at a definable distance from this book block edge. In two-up processing, the scraper 7 can also be briefly closed in the center of the block spine in order to maintain the region of the separating cut free of glue. The application position, application length and application thickness can be changed by means of the machine control 36.
When the linear drive 30 is switched off or the gluing station 1 is changed, the coupler 24 is supported on an adjustable stop 25 that simultaneously defines the zero position of the scraper 7 for completely scraping the glue 3 off the application roller 5.
Number | Date | Country | Kind |
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10 2009 031 949.2 | Jul 2009 | DE | national |