Frankieboy
Mechanical
We are actually working on the redesign of a central impression cylinder flexo printing machine for printing of polyethylene film, including a gear train of four gears:
Bull gear drive gear Z = 44
Bull gear Z = 440
Printing cylinder gear (changeable gear) Z varies between 31 and 100
Anilox drive gear Z = 44
The bull gear drive gear drives the bull gear, the bull gear drives the printing cylinder gear and the printing cylinder gear drives the anilox drive gear. Each gear (except the bull gear drive gear) drives a cylinder:
Bull gear drive gear: no cylinder
Bull gear: central impression cylinder (diameter 1,400.52 mm)
Printing cylinder gear: printing cylinder (diameter 98.676 - 318.310 mm)
Anilox drive gear: anilox roller (diameter 140.052 mm)
Other data:
Normal basic rack profile alfa = 20 degrees
Normal modul Mn = 2.75 mm
Tangential modul Mt = 3.1831 mm
Tangential pitch Pt = 10.000 mm
Pressure angle beta = 30 degrees 14 minutes 18.04 seconds
I'm not happy with the drive ratios, so we'll exchange the bull gear drive gear. Maybe we'll exchange the bull gear drive gear as well, but this includes the replacement of the central impression cylinder as well, and we didn't decide on this yet.
The number of teeth of the printing cylinder gear depends on the printing cylinder diameter used; the number of teeth varies between 31 and 100.
The actual machine is a machine already in use, but we suffer of big gear problems. One of the problems is the normal module used for the gears are not the same, so we suffer of vibrations and a huge amount of noise.
Precision of drive and reduction of vibration to the minimum is essential in order to guarantee best printing results.
I have a few questions
I checked the possibility to use an addendum modification coefficient (x) for the gears in order to improve the printing results (less vibration). I discovered (I'm not a experienced gear designer) the calculated cylinder surface diameter (c) of the central impression cylinder varies with the diameter variation of the printing cylinder:
Example:
X bull gear = -0.1 / X printing cylinder drive gear = -0.1
Printing cylinder gear: Z = 31; C bull gear = 1,399.533 mm / C printing cylinder drive gear = 98,603 mm
Printing cylinder gear: Z = 75; C bull gear = 1.399,621mm / C printing cylinder drive gear = 238,572 mm
X bull gear = 0 / X printing cylinder drive gear = 0
Printing cylinder gear: Z = 31; C bull gear = 1.400,563 mm / C printing cylinder drive gear = 98,676 mm
Printing cylinder gear: Z = 75; C bull gear = 1.400,563 mm / C printing cylinder drive gear = 238,732 mm
I think (but I¡¦m not sure) this is unacceptable, so using an addendum modification coefficient is not possible.
I checked the diameter of the central impression cylinder in relation to the number of teeth of the bull gear of some central impression printing machines, and I found some very strange figures (tangential module and tangential pitch are the same as listed previously). These are:
Machine 1: diameter central impression cylinder: 1,400.52 mm --> number of teeth: 440 (real figure); pitch diameter: 1,400.563 mm. Difference maybe in order to take thickness of material printing on into account?
Machine 2: diameter central impression cylinder: 2.276,84 mm --> number of teeth: 715,29 (calculated figure) --> not possible --> central impression cylinder is 0.92 mm bigger (circumferential difference: 2.90 mm) or 2.26 mm smaller (circumferential difference: 7.10 mm) than the pitch diameter.
I don't understand machine 2. The total number of teeth is of course a whole number, so something is happening. A difference of 0.92 mm or 2.26 mm is to my opinion too much. Who knows the answer?
Bull gear drive gear Z = 44
Bull gear Z = 440
Printing cylinder gear (changeable gear) Z varies between 31 and 100
Anilox drive gear Z = 44
The bull gear drive gear drives the bull gear, the bull gear drives the printing cylinder gear and the printing cylinder gear drives the anilox drive gear. Each gear (except the bull gear drive gear) drives a cylinder:
Bull gear drive gear: no cylinder
Bull gear: central impression cylinder (diameter 1,400.52 mm)
Printing cylinder gear: printing cylinder (diameter 98.676 - 318.310 mm)
Anilox drive gear: anilox roller (diameter 140.052 mm)
Other data:
Normal basic rack profile alfa = 20 degrees
Normal modul Mn = 2.75 mm
Tangential modul Mt = 3.1831 mm
Tangential pitch Pt = 10.000 mm
Pressure angle beta = 30 degrees 14 minutes 18.04 seconds
I'm not happy with the drive ratios, so we'll exchange the bull gear drive gear. Maybe we'll exchange the bull gear drive gear as well, but this includes the replacement of the central impression cylinder as well, and we didn't decide on this yet.
The number of teeth of the printing cylinder gear depends on the printing cylinder diameter used; the number of teeth varies between 31 and 100.
The actual machine is a machine already in use, but we suffer of big gear problems. One of the problems is the normal module used for the gears are not the same, so we suffer of vibrations and a huge amount of noise.
Precision of drive and reduction of vibration to the minimum is essential in order to guarantee best printing results.
I have a few questions
I checked the possibility to use an addendum modification coefficient (x) for the gears in order to improve the printing results (less vibration). I discovered (I'm not a experienced gear designer) the calculated cylinder surface diameter (c) of the central impression cylinder varies with the diameter variation of the printing cylinder:
Example:
X bull gear = -0.1 / X printing cylinder drive gear = -0.1
Printing cylinder gear: Z = 31; C bull gear = 1,399.533 mm / C printing cylinder drive gear = 98,603 mm
Printing cylinder gear: Z = 75; C bull gear = 1.399,621mm / C printing cylinder drive gear = 238,572 mm
X bull gear = 0 / X printing cylinder drive gear = 0
Printing cylinder gear: Z = 31; C bull gear = 1.400,563 mm / C printing cylinder drive gear = 98,676 mm
Printing cylinder gear: Z = 75; C bull gear = 1.400,563 mm / C printing cylinder drive gear = 238,732 mm
I think (but I¡¦m not sure) this is unacceptable, so using an addendum modification coefficient is not possible.
I checked the diameter of the central impression cylinder in relation to the number of teeth of the bull gear of some central impression printing machines, and I found some very strange figures (tangential module and tangential pitch are the same as listed previously). These are:
Machine 1: diameter central impression cylinder: 1,400.52 mm --> number of teeth: 440 (real figure); pitch diameter: 1,400.563 mm. Difference maybe in order to take thickness of material printing on into account?
Machine 2: diameter central impression cylinder: 2.276,84 mm --> number of teeth: 715,29 (calculated figure) --> not possible --> central impression cylinder is 0.92 mm bigger (circumferential difference: 2.90 mm) or 2.26 mm smaller (circumferential difference: 7.10 mm) than the pitch diameter.
I don't understand machine 2. The total number of teeth is of course a whole number, so something is happening. A difference of 0.92 mm or 2.26 mm is to my opinion too much. Who knows the answer?
