Abrasive-holding plate

MICHELE GASPARINI   michele.gasparini.2@studenti.unipd.it
 

Introduction

the production of marble and granite slabs has always been an important business and the technologies to obtain stronger and better-looking slabs are in continuous development.

Murble and Granite, during process of formation, need to be smooth. The surface, after cutting operation, present high roughness and opaque colours. The SG8 is the new “head” with 8 The abrasive-holding plate. It is the principal component of the calibrating and polishing machines.

Cattura

Objectives

We want to use Adams to simulate the kinematics of the system and calculate the binding reactions that derive from the contact between the slab and the plate. It was decided to use the adams model of contacts because even if it is a phenomenon material removal, it is not comparable to cutting removals as in metals. This is because the removed thickness is very small and the removal phenomenon depends only on the friction between surfaces.

The key steps of the work are the following:

  • 3d modelling of the entire system ( cam, flange, carte, plate, pin )
  • Importing in ADAMS of all components
  • Definition of component properties
  • Select of joints
  • Simulation of emptying process
  • Creation of contact ( slab-plate)
  • Calibration of Adams model and physical model
  • Bodies motion simulation
  • Comparison with sperimental prove

The modelling problem

Most of multybody sistem components have been designed by SolidEdge 3d Software. The images below show the parts created

sss

The kinematic chain in composed by a translational joint that simulate beam, a cylinder between cam and flange along an axis inclined with respect to the principal.

For each component was defined a material in order to know exactly important properties like mass, moments of inertia and center of gravity position. This operation has been done in Solid Edge and after compared to the standard properties of Adams and this are the same.

JOINTS

Type and number of joints affect also the system’s degrees of freedom, while redundant constraints can cause integration problems. According to Grubler’s Formula this is the status of the system:

WhatsApp Image 2018-09-08 at 15.24.48

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After that it has been inserted contact between slab and plate using solid to solid. the static friction coefficient has been calculated in a real prove in the measuring laboratory.

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Simulations and analysis of results

For calibrate physical and Adams models you have created in Adams an assembly where the plates are stopped and without the tilting flange. In this case it is possible to extract static and dynamic friction coefficents from the prove where angular velocity and pressure are zero.

SDDD

After that the prove has been done with a pressure eguale to 1 bar and a rotation of the cam egual to 313 rpm.

The first result is the rotation of plate during asportation work: in the theory design the rotation has to be 8° and the result of Adams model is the following

ROTATION

While the angular velocity is:

VELOCI

This results are in according with the project.

After that the focus has shifted towards the forces developed during work. The secondary objective is to compare the constrain force along Y with the experimental prove. This prove consist to evaluate the beam work force for each polishing spindle in working conditions. An equipment+instrumentation was created to extract the value of the slab-abrasive interface force

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From ADAMS we extract the force from the actuator that move the system along Y direction. The results are the following:

FORCE

CONTACT

MOMENT

The force calculate along Y is 1400 N and the force calculate in experimental prove is 1250N.

Conclusion

This project has served to see the versatility of the software useful for studying kinematics in a fast and interfaceable way with the various design software. It can aslo be used as a simulator of removal mecchanisms in the world of marble and granite, where the removal thicknesses are very small and the speed are low.

 

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