Gluing apparatus

The invention relates to a gluing apparatus which can be used in particular as part of a book casing-in machine. The gluing apparatus includes an application roller for applying a glue layer to a surface to be glued and a dosing roller for dosing the amount of glue. The application roller comprises an axis-parallel depression and the dosing roller comprises an axis-parallel projection engaging in the depression. The profile of the projection (20) of the dosing roller (2) merges from the cylindrical peripheral surface (4) via an involute into a coaxial cylindrical portion (22) of greater diameter while the profile of the depression (10) of the application roller (1) merges from the cylindrical peripheral surface (3) via a curve forming the counter profile to the involute of the projection (20) into a coaxial cylindrical portion (12) of smaller diameter. The configuration of the profiles of the application roller and the dosing roller according to the invention permit simple and economic production of the rollers and ensures that the glue bead can escape upwardly out of the roller gap unrestricted and without any danger of inclusions.

The invention relates to a gluing apparatus in particular for inner books 
to be cased in book cases in casing-in machines, comprising an application 
roller associated with a surface area to be glued, rolling on the latter 
and thereby leaving behind a glue layer and a dosing roller which is 
associated with said application roller and has an opposite direction of 
rotation, and for the fold gluing the application roller is provided with 
an axis-parallel depression and the dosing roller with an axis-parallel 
projection engaging in said depression. 
In such gluing apparatuses the application roller serves to provide the 
surface area of the inner book to be glued with the necessary glue 
application and the dosing roller imparts to the application roller the 
correct uniform glue coating, for example from a glue bead present in the 
roller wedge. The axis-parallel depression of the application roller 
receives the projecting fold of the inner book and ensures the correct 
gluing thereof. The projection of the dosing roller emerges on passage 
through the joint rolling zone into the depression in order firstly to 
ensure the closure in this region and secondly to ensure the correct glue 
coating in the depression. 
For the correct functioning of the gluing apparatus in particular the 
cooperating profiles of the depression of the application roller and the 
projection of the dosing roller are important. These profiles must be made 
such that on interengaging in the rolling zone they maintain the correct 
closure of the roller wedge which permits the unrestricted escape of the 
glue bead disposed between the rollers without any danger of inclusions, 
and ensure the correct glue application on the active faces of the 
depression. Hitherto, these various requirements could be met only with 
relatively complicated profiles which were difficult to make. 
The problem underlying the invention is the provision of a gluing apparatus 
of the type set forth at the beginning in which the requirements indicated 
are optimally met with a simple profile form of the rollers which is easy 
to make. 
According to the invention this problem is solved in that the profile of 
the projection at the entry portion lying at the front in the direction of 
rotation merges via an involute from the cylindrical peripheral surface of 
the dosing roller into a coaxial cylindrical portion of greater diameter 
and that the profile of the depression at the entry portion lying at the 
front in the direction of rotation merges via a curve forming the counter 
profile to the involute of the projection from the cylindrical peripheral 
surface of the application roller into a coaxial cylindrical portion of 
smaller diameter. 
According to a preferred embodiment of the invention the curve forming the 
profile of the entry portion of the depression is an involute forming the 
counter profile to the involute of the projection. In this case the 
involutes of the projection and the depression are preferably formed with 
an engagement angle of 45.degree.. 
A further advantageous development of the gluing apparatus according to the 
invention resides in that the profile of the projection merges at the exit 
portion lying behind in the direction of rotation via an eccentric 
cylindrical portion of smaller diameter from the coaxial cylindrical 
portion into the cylindrical peripheral surface of the dosing roller and 
that the transition of the depression from the coaxial cylindrical portion 
of small diameter to the cylindrical peripheral surface of the application 
roller in the exit portion is formed as counter profile to the eccentric 
cylindrical exit portion of the projection. 
Due to the configuration of the profiles of the depression of the 
application roller and the projection of the dosing roller when the 
projection enters into the depression due to the rolling of the involute 
flank on the matching counter profile the glue bead can escape upwardly 
unrestricted without any danger of inclusions. During the entire passage 
through the rolling zone the reliable closure of the roller wedge is 
ensured. Furthermore, the matched profiles of the projection and 
depression ensure the proper glue application in particular on the surface 
portion of the depression effective for the gluing of the fold. 
A particular advantage of the profile configuration according to the 
invention is the favourable manufacturability because of the simple 
geometry because the profiles are made up essentially only of circles and 
involutes which can be easily designed and mechanically made without any 
problems.

FIG. 1 shows diagrammatically in side view the one gluing mechanism of a 
gluing apparatus for a book casing-in machine. The gluing mechanism 
consists essentially of an application roller 1 and a dosing roller 2 
whose peripheral profiles can be seen in the drawing. 
The application roller 1 comprises over the greater part of its periphery a 
cylindrical peripheral surface 3 having the radius R.sub.1 and the dosing 
roller 2 is formed in corresponding manner over the major part of its 
periphery with a cylindrical peripheral surface 4 having preferably the 
same radius R.sub.1. The axes of the two rollers lie in a common 
horizontal diameter plane, the axis spacing being substantially equal to 
the sum of the two radii R.sub.1 so that the rollers 1 and 2 are 
completely or almost tangential in a rolling zone 5. A glue supply means 
not illustrated ensures a constant amount of glue 6 in the wedge of the 
two rollers 1 and 2. 
The two rollers 1 and 2 are driven in opposite senses in the direction of 
the arrows so that their peripheral surfaces pass through the rolling zone 
5 from the top to the bottom. The dosing roller 2 ensures that the surface 
of the application roller 1 entrains a glue coating of predetermined 
thickness. The glue coating thickness can be defined by the axis spacing 
of the two rollers and/or by depressions in the surface of the application 
roller 1. 
The application roller 1 transfers the entrained glue coating to the one 
side of an inner book 7 which at the point substantially diametrically 
opposite the rolling zone 5 is moved in contact with the application 
roller 1 from the bottom to the top. For the gluing of the other side of 
the inner block the gluing apparatus comprises a second gluing mechanism 
which is arranged laterally inverted with respect to the gluing mechanism 
illustrated but which for simplification has not been shown. 
To ensure that the correct gluing of the fold 8 of the book 7 is achieved 
the application roller is provided with a depression 10 which is deep 
enough to be able to receive the fold 8 of the inner book 7. On the dosing 
roller 2 a projection 20 complementary to the depression 10 is formed 
which on rotation of the rollers penetrates into the depression 10 when 
the latter runs through the rolling zone 5 (FIG. 2). The projection 20 
ensures that on this passage through the rolling zone the amount of glue 6 
disposed in the roller wedge is retained and the surfaces of the 
depression 10 receive the glue coating necessary for proper gluing of the 
fold 8. The profiles of the depression 10 and the projection 20 are 
important for this purpose. 
The depression 10 and the projection 20 extend parallel to the axes of the 
rollers 1 and 2, i.e. perpendicular to the plane of the drawing of FIG. 1, 
with constant profile as will be explained hereinafter with the aid of 
FIG. 1. 
The profile of the depression 10 consists of three portions, that is the 
entry portion 11 leading in the direction of rotation, the centre portion 
12 forming the lowermost point and the exit portion 13 trailing in the 
direction of rotation. In corresponding manner the profile of the 
projection 20 consists of three portions, i.e. the entry portion 21 
leading in the direction of rotation, the centre portion 22 forming the 
greatest protruberance and the exit portion 23 trailing in the direction 
of rotation. The centre portion 12 which occupies the greater part of the 
angular extent of the depression 10 is formed by a cylindrical surface 
which is coaxial with the peripheral surface 3 of the application roller 1 
and the radius R.sub.2 of which is smaller than the radius R.sub.1 of the 
peripheral surface 3. The depth of the depression 10 is given by the 
radius difference .DELTA.R=R.sub.1 -R.sub.2. The angular extent .alpha. of 
the cylindrical centre portion 12 may be about 30.degree.. 
In complementary manner the centre portion 22 of the projection 20 is 
formed by a cylindrical surface which is coaxial with the peripheral 
surface 4 of the dosing roller 2 and the radius R.sub.3 of which is 
greater by the radius difference .DELTA.R than the radius R.sub.1 of the 
peripheral surface 4. The centre portion 22 has the same angular extent 
.alpha. as the centre portion 12 of the depression 10. Thus, the centre 
portions 12 and 22 are tangent to each other on passage through the 
rolling zone 5 (FIG. 2) in the same manner as the peripheral surfaces 3 
and 4 of the two rollers. 
The entry portion 11 of the depression 10 forms the transition from the 
cylindrical peripheral surface 3 to the cylindrical centre portion 12 and 
in corresponding manner the entry portion 21 of the projection 20 forms 
the transition from the cylindrical peripheral surface 4 to the 
cylindrical centre portion 22. The profiles of these transitions are 
important in order to ensure on entry of the projection 20 into the 
depression 10 the correct closure in the rolling zone 5 and also that the 
glue bead which has previously penetrated into the depression 10 can 
escape upwardly unrestricted without undesirable inclusions. 
An important feature of the profile form shown resides in that the profile 
of the entry portion 21 of the projection 20 is formed by an involute so 
that the front flank of the projection 20 forming the entry portion 21 
corresponds to the tooth flank of an involute toothing. The profile of the 
entry portion 11 of the depression 10 forms the necessary counter profile 
to the involute flank of the projection 20. Preferably this counter 
profile is also formed by an involute so that the two entry profiles 
cooperate like the tooth flanks of an involute toothing and on entry of 
the projection 20 into the depression 10 roll on each other in accordance 
with the laws governing tooth engagement. These are of course circular 
involutes, the radius of the base circle of the involute being less than 
the radius R.sub.1 of the rollers. Preferably, the involute flanks of the 
entry portions 11 and 21 are formed with an engagement angle of 
45.degree.. By this profile form the optimum conditions are obtained on 
entry of the projection 20 into the depression 10. Furthermore, the 
involute flanks 11 and 21 can be designed and made by the known gear 
toothing techniques in simple manner. 
The exit portion 13 of the depression 10 forms the transition from the 
recessed cylindrical centre portion 12 to the cylindrical peripheral 
surface 3 and it is the portion of the depression 10 which is effective in 
the gluing of the fold 8. The exit portion 23 of the projection 20 forms 
in corresponding manner the transition from the cylindrical centre portion 
22 to the cylindrical peripheral surface 4 and it cooperates on exit of 
the projetion 20 from the depression 10 with the exit portion 13 of the 
depression 10 to obtain the correct glue application. It has been found 
that particularly good results can be obtained in the exit region when the 
profile of the exit portion 23 of the projection 20 is formed by a 
cylindrical surface portion whose radius R.sub.4 is substantially smaller 
than the radius R.sub.1 of the peripheral surface 4 and whose axis lies 
eccentrically with respect to the axis of the dosing roller 2. The 
cylindrical exit portion 23 with the radius R.sub.4 adjoins the 
cylindrical centre portion 22 with the radius R.sub.3 tangentially and 
extends over a centre angle .beta. which is greater than 60.degree. and 
less than 90.degree.. 
The profile of the exit portion 13 of the depression 10 is formed as 
counter profile to the profile of the cylindrical exit portion 23 of the 
projection 20 so that on passage through the rolling zone 5 (FIG. 4) the 
profiles roll on each other and thus ensure the necessary closure and that 
the proper glue application is obtained. The resulting profile form of the 
exit portion 13 also gives the proper gluing of the fold 8.