Arrangement of a furnace and of bulk material of glass particles as well as method for operating a furnace

Patent metadata

Field	Value
Publication number	US-11808520-B2
Application number	US-201716349743-A
Country	US
Kind code	B2
Filing date	Nov 14, 2017
Priority date	Nov 15, 2016
Publication date	Nov 7, 2023
Grant date	Nov 7, 2023

Abstract

The invention relates to an arrangement of a furnace and of bulk material of glass particles, said furnace ( 10 ) comprising a pressing punch ( 36 ), a pressure, distance and/or speed sensor and a control device for controlling a pressing process based on the output signal of the sensor. The sensor detects at least a pressure, position and/or motion parameter of the pressing punch ( 36 ). The pressing punch ( 36 ) acts on the bulk material of glass particles ( 32 )—possibly via an interposed ram ( 28 )—, said glass particles being guided and crystallizable in a press channel ( 30 ). The trigger criterion for the process control is a change of at least a motion parameter of the pressing punch ( 36 ) upon softening of the bulk material of glass particles ( 32 ) which change is detected by the sensor.

First claim

The invention claimed is:

1. An arrangement of a furnace and of bulk material of glass particles comprising
a furnace, and
bulk material of glass particles,
wherein said furnace comprises
a muffle,
a pressing punch,
a pressure, distance and/or speed sensor and
a process controller configured for controlling a pressing process based on an output signal of the sensor,

wherein the sensor detects at least a pressure, position and/or motion parameter of the pressing punch,
wherein the pressing punch acts on the bulk material of glass particles,
wherein said glass particles are guided and crystallizable in a press channel,
wherein trigger criterion for the process controller is a change of at least a motion parameter of the pressing punch upon softening of the bulk material of glass particles which change is detected by the sensor,
wherein the sensor, below the softening temperature of the bulk material of glass particles, detects the thermal expansion of the muffle, a ram of the pressing punch, and the bulk material of glass particles, said thermal expansion counteracting the press force.

2. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein the process controller controls the start of the pressing process, in which start the furnace temperature, the pressure in a firing chamber of the furnace and a press force of the pressing punch are controlled by the process controller, and
wherein the process controller controls the end of the pressing process, in which end the press force of the pressing punch is reduced by the process controller, and the furnace temperature is reduced by the process controller.

3. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 2 ,
wherein the press force of the pressing punch is reduced by the process controller to zero and the furnace temperature is reduced by the process controller by turning off the furnace ( 10 ).

4. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein the bulk material of glass particles forms gradients, in the press channel.

5. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 4 ,
wherein the gradients formed comprise color and/or translucency gradients.

6. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 4 ,
wherein the gradients correspond to at least a gradual change layer by layer and/or a continuous change of a physical property of the bulk material of glass particles.

7. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein the bulk material of glass particles comprises different dyed glass particles and/or at least one glass type which is dyed differently with pigments, and/or glass with different contents of nucleating agents and/or with different densities.

8. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein the at least one motion parameter comprises micro pulses and wherein a start of the pressing process is the termination of micro pulses of the motion parameter and/or the number thereof and/or the temporal distance thereof.

9. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 8 ,
wherein the micro pulses reflect a short-term and small motion between the bulk material of glass particles and the muffle.

10. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 8 ,
wherein the process controller detects a number of micro pulses of the motion parameter and/or a distance between the micro pulses and/or a change in distance between the micro pulses and/or a size of the micro pulses and uses one or more detected criterion for the process controller.

11. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein the trigger criterion for an end of the pressing process is a decrease of pressing speed to a value close to zero or a value of less than 5% or a value of less than 2% of maximum pressing speed of the pressing punch.

12. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein the process controller detects a backward motion of the pressing punch in correspondence with the thermal expansion of the bulk material of glass particles via the sensor, and
wherein the trigger criterion for the process controller to start the pressing process is an end of the backward motion and/or the beginning of a forward motion and/or a defined point in time after a change of motion parameters of the pressing punch.

13. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein the sensor supplies the decreasing counterforce which corresponds to the softening of the bulk material of glass particles due to thermal expansion coefficients or due to differences between thermal expansion coefficients to the process controller,
wherein the process controller sets a further process sequence to a point in time after detection of the softening of the bulk material of glass particles.

14. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein the process controller brings the pressing punch into contact with the bulk material of glass particles before the actual pressing process and detects the thermal expansion of the bulk material of glass particles corresponding to a motion of the pressing punch against the direction of pressing and uses the decreasing counterforce if no further thermal expansion takes place or upon softening.

15. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein the process controller causes the pressing punch to exert a press force or a press power onto the bulk material of glass particles before the bulk material of glass particles has softened.

16. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein based on the motion parameter detected by the sensor, the press power exerted by the pressing punch and/or the temperature of a temperature sensor disposed in or at the firing chamber, the process controller identifies the type and the material of the bulk material of glass particles based on predefined signatures and controls the pressing process.

17. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein during the detection of the motion parameter the pressing punch exerts a constant force or a force which follows a predefined profile onto the bulk material of glass particles and the motion parameter is detected after the pressing punch has been brought into contact with the bulk material of glass particles.

18. The arrangement of a furnace and of bulk material of glass particles as claimed in claim 1 ,
wherein the pressing punch is moved to a predefined extent during the heating of the bulk material of glass particles.

19. A method for operating a furnace comprising a muffle, a pressing punch, a pressure, distance and/or speed sensor and a process controller for controlling a pressing process comprising,
detecting, with the pressure, distance and/or speed sensor, at least a pressure, position and/or motion parameter of the pressing punch,
controlling, with the process controller, the pressing process based on an output signal of the sen

Assignees

• Ivoclar Vivadent Ag

Inventors

• Jussel Rudolf
• Bürke Harald

Classifications

• F27B17/025 Primary

  for dental workpieces · CPC title

• A61C13/083

  Porcelain or ceramic teeth {(A61C13/081 takes precedence; preparations A61K6/80)} · CPC title

• A61C13/20

  Methods or devices for soldering, casting, moulding or melting {(A61C13/04, A61C13/081 take precedence)} · CPC title

• A61K6/853

  Silicates · CPC title

• C03B19/09

  by fusing powdered glass in a shaping mould · CPC title