The machine is designed as a FULL AUTOMATIC HOT PRESSING SYSTEM complete of weighting system for mixture, automatic loading/unloading device for back-plates and post-curing station.
- 1 to 4 single presses
- 1 to 4 hydraulic units
- Positive moulds individually heated with 5 thermocouple for temperature control
- Self adjusting scales for MIX and UL (±1 g tolerance)
- Quick change over time (fast tools change: 15 min. each press)
- Two moulds for each press (extended stroke for copper free mixtures)
- Accurate levelling system for mixture.
- Each pads independently pressed
- Parameter storing software for quality certification
- Low man power required
- Optional Post-curing stations (n° 2 pneumatic presses each ) for cycle time reduction
TECHNICAL FEATURES OF THE PRESS
a) Bearing structure realised with a C-frame connected by 1 steel column, rigidly by mean of pre-loading ring.
b) Mould-holder group built in C 40 steel, suitable to receive moulds up to 250 mm dia.
c) Independent cylinders (n°2) for pressing in top quality steel, integrated on the mould holder structure.
d) Pressing rod in tempered steel, chromed and rectified. The chrome thickness is 0,1 ÷0,15 mm with 60 HRC hardness.
e) The cylinder seals comply with the most updated technologies and they guarantee a very low friction coefficient, optimal tightness at low-high pressure as well a high resistance to abrasive powders.
f) Control of the positions on the punches by means of linear transducers. Reading of the data on the display.
g) Survey of the pressure by means of a pressure transducer with strain-gauge sensor. It is connected to an analogical input of the PLC and allows to visualize on display the mould clamping force in Tons.
h) Speed and pressure regulations with feed-back proportional valves linked to a pump with variable capacity. It has to be pointed out that the pump used is for high pressures and at low sound level (75÷78 dB).
i) Hydraulic unit with motor-pump controlled by inverter for energy saving.
j) Distribution groups represented by a special alloy steel block checked by means of U.S. - class 2, on which are housed the valves which are the running logic. These valves comply with CETOP and DIN regulations. The oil tank will be equipped with water/oil heating exchanger with relevant thermostatic valve.
k) Safety protections on the four sides of the presses consisting in fixed frames and gates protected by limit switches in compliance with safety specifications.
l) Control of the cycle by means of PLC SIEMENS S7-300 interfaced with an operator terminal fitted with 9" colour touch-screen display TP900 Confort. The operator panel is the only common electronic component
- Pump Rexroth/Bosch
- Proportional valves Rexroth/Bosch
- Pneumatics Pneumax/Festo
- Valves Rexroth/Atos
- PLC Siemens
The machine is fitted with:
1) Rotary table
The rotating table, by an alternate rotation of 180°, is able to move two mould holder units: one under the press and the other outside the operating zone (also used to change the moulds).
The rotating table solution allows to have one only equipped side with all ancillary devices as required by the translating matrixes solution.
In order to obtain a precise positioning of the table, a mechanic indexing system has been provided.
2) Compound transport device
The system is composed by 2 double buckets where the dosing machines discharge the doses of compound and underlayer (opt). The buckets are fixed on a slide that move itself from the scales position to the presses.
3) Compound distribution device
The system composed by small boxes where the dosing machines unload the doses of compound and underlayer (opt). The boxes provide, with a special movement, the distribution of the powders within the cavities of the mould.
The unit is furthermore equipped with levelling punches that allow the levelling of the compound before the underlayer load (if supplied). The compound loading chambers are created by a vertical movement of the punches (the size of the chambers may vary, but staying within the field of the punches sliding= 150 mm max.), which determines the distribution of the powders. A linear transducer makes the control of the chamber opening.
4) Backing plates Magazines
Each press is equipped with a vertical magazine for the metal supports located in the operating zone. The magazines have a height of 400 mm therefore the autonomy is for about 80 plates. The magazine can be filled during the automatic cycle of the machine because the area where the magazine is located is protected independently
5) Electronic dosing machines
With a built-in powder container of 45 lt capacity , for automatic weighing of powder and mixture of powder for brake pads production.
Auto-learning system of the dosing parameters: it is only necessary to set the weight and the tolerance, while the machine determines, according to these two values and the type of powder, the belt speed. Feeding system by belt conveyor in order to avoid segregation of the powders.
Weight resolution: 1 g
Tolerance of weight: 1 g
Self-tare for offset zeroing at every weighing cycle.
Self-diagnostic: message on display with error acoustic alarm
Fast emptying for powder replacement
Sensors for min-max level of powder on the powder container
Setting parameter and on-line page visualized on the control panel of the press
Automatic discharge of the doses with wrong weight
Dust suction conveyors
The standard machine is equipped with 2 scales (1 for the compound and 1 for the underlayer or alternative compound) which can be 4 on request (3 for the compounds and 1 for the underlayer) to allow the contemporaneous production of pads with different compounds.
6) Pads unloading unit
The pressed pads are unloaded from the press by a pneumatic pick and place provided of magnets and are consequently moved on a pick and place that will convey them towards the following stations of the production line (post-curing station).
A diverter is installed on the unloading unit to allow the eventual rejects of pads with parameters not within the required tolerances.
7) Mould cleaning and antisticking sprayer unit
The machine is equipped with a cleaning unit that provides to clean the mould and the pressing platen by brushing. Moreover, on the same unit, nozzles provide to spray detaching liquid on the punches of the mould and on the pressing platen.
8) Pick and place unit
For positioning pads from pads unloading unit(6) to post curing unit (9) and from post curing unit (9) to the unloading conveyor (10). Moreover, on the same unit, a brush provide to clean the heating plates and a nozzle provide to spray anti sticking liquid on the pressing platen.
9) Post-curing unit
The goal of this unit is to ensure pads to have the second curing phase, composed of n. 2 pressing units each press. The pads are constantly kept under pressure one by one in order to allow the compound to complete the first curing and the glue to anchor the moulded pad to the metal support. This treatment will allow the final curing (if needed) of the pads in the oven at controlled temperature cycle. The system is servo-assisted by a Pick & Place unit (pt. 8).Under request, each post curing station can have transducers for feedback signals of pressing force and thickness of the pads for quality control.
10) Unloading conveyor (opt)
The unloading belt will be put in a position to collect and transfer the pads from the unloading area of the Pick & Place (8) to the container that stores the pads or to a following step of the process.
The PLC of the machine allows the adjustment of all working parameters and the storing of the programs on SD Card. The number of storable programmes depends on the capacity of the SD Card inserted in the PLC.
The following parameters can be stored:
- Pressing time (sec)
- N° of vents (n°)
- Mould Temperature (C°)
- Punches temperature (C°)
- Pressing platen Temperature (C°)
- Pressing Force (KN)
- Final thickness of pads (mm)
All production data can be stored on .cvs files (Excel compatible) and stored on the memory card, or sent through Ethernet to an outside PC. As option, the operator working software, make graphics analysis of all working parameters and printout.
Sequence of operations
a) After filling operations (scales or elevators and back plates magazines), the operator start the automatic cycle.
b) The scales(5) start to weight the compound and the underlayer, if provided.
c) The compound is discharged on the compound transport device (2) and moved over the first press.
d) The compound is discharged on the distribution devices (3) and the mould cavities are filled.
e) The levelling punches press gently the powder in to the cavities.
f) The underlayer is discharged on the distribution devices and the mould cavities are filled.
g) After the completion of the material distribution, the back plates are picked from the magazines (4) and placed on to the mould.
h) The rotating table (1) move the filled mould under the press and the curing cycle start.
i) At the same time, the second mould is filled as previously described
j) After the first curing cycle, the pads unloading unit (6) discharge the mould and place the pads on to the pick and place's magnet (8).
k) The mould is cleaned and the antisticking liquid (7) is sprayed on to the surface in contact with the friction material. On the same time the pick and place (8) move the pads under the post curing units (9).
l) The table rotate back and the cycle repeats.
m) At the end of the curing cycle under the post-curing units(9), the pick and place (8) provide to download the pads over the unloading belt conveyor (10).