Method of and apparatus for adjusting comminuting machines

• US 5,226,604 A
• Filed: 12/17/1991
• Issued: 07/13/1993
• Est. Priority Date: 04/07/1989
• Status: Expired due to Fees

• Current Assignee: HAZEMAG & EPR GmbH (Schmidt, Kranz & Co. GmbH)
• Original Assignee: Salzgitter Maschinenbau GmbH
• Inventors: Hung, Hiep P., Seiffert, Klaus-Peter
• Primary Examiner(s): Rosenbaum, Mark
• Assistant Examiner(s): HAN, FRANCES CHIN
• Application Number:
  US07/808,645
• Time in Patent Office: 574 Days
• Field of Search: 241/30, 241/34, 241/37, 241/189.1, 241/290
• US Class Current: 241/30
• CPC Class Codes: B02C 13/095 with an adjustable anvil or impact plate

Abstract

The width of the clearance between a rotor with orbiting beaters and a pivotable impact plate of a machine for comminuting coal, rock, and like materials is adjusted by a computer which controls a reversible motor serving to pivot the impact plate relative to the path of orbital movement of the beaters. The computer causes the plate to pivot toward the path of the beaters when it receives a signal that the admission of material into the housing of the comminuting machine is interrupted and a converted acoustic signal denoting that the machine generates sounds which are indicative of completed evacuation of material from the housing. The direction of pivotal movement of the plate is reversed when the computer receives a series of converted acoustic signals or a single converted acoustic signal denoting that the width of the clearance has been reduced to zero, i.e., that the beaters actually strike the adjacent portion of the plate. The computer arrests the motor when the width of the clearance reaches a preselected value and the computer thereupon initiates renewed admission of material into the housing.

Claims

1. A method of operating a comminuting machine, wherein a driven first tool carries beaters which move along a predetermined path adjacent a mobile second tool to define a clearance with the second tool, said clearance determines the particle size of the comminuted product as a result of admission into the clearance, comprising the steps of

interrupting the feeding of material into the machine;

allowing the machine to be emptied of material;

generating first signals based on a first sound of the emptied machine;

electronically processing the first signals corresponding to said first sound having a first sound intensity of said machine running without feed of materials after an evacuation of comminuted material from the machine;

feeding said processed first signals to a drive connected to said second tool and initiating a drive;

moving said second tool actuated by said drive toward said path of the beaters until said beaters strike said second tool with attendant generation of a second sound having a predetermined second intensity;

electronically processing and distinguishing a second signal derived from said second sound of the second intensity from said first signal representing said first sound intensity; and

retracting said second tool from said path in response to the generation of said second sound to establish a clearance having a predetermined width.

2. The method of claim 1 of operating a comminuting machine wherein

said comminuting machine generates a third sound, representing loaded running and having a third intensity generally larger than said predetermined first intensity in absence of material, said moving step further comprising monitoring sounds of the machine;

generating a first signal when the intensity of monitored sounds falls below said third intensity; and

utilizing said first signal to terminate associated with an emptying of the machine and to begin a moving step of said second tool toward said first tool.

3. The method of claim 2 of operating a comminuting machine which is an impact crusher and wherein said first tool has a rotor which orbits its beaters along an endless path, further comprising the step of repeating said interrupting, generating, processing, feeding, moving and retracting steps at suitable time intervals to compensate for wear upon said tools.

4. The method of claim 1 of operating a comminuting machine wherein said beaters strike said second tool at predetermined time intervals, wherein the duration of the predetermined time intervals is a function of the speed of advancement of said beaters along said path with attendant generation of a series of second sounds having said second intensity, further comprising the steps of

monitoring the intensity and frequency of second sounds and generating second signals when the intensity of said second sounds corresponds to one of said second sound intensities;

interrupting said moving step in response to a first one of said second signals;

resuming the moving step when the time interval between said first one of said second signals and a next-following second signal is longer than one of said predetermined time intervals; and

starting said retracting step in response to the generation of a predetermined number of second signals occurring at said predetermined time intervals.

5. The method of claim 1 of operating a comminuting machine, wherein said beaters strike said second tool at predetermined intervals, the duration of which is a function of the speed of advancement of beaters along said path with attendant generation of a series of second sounds having said predetermined second intensity, further comprising the steps of

monitoring the intensity and frequency of said second sounds and generating second signals when the intensity of said second sounds corresponds to said predetermined second intensity;

interrupting the moving step in response to said second signal; and

starting said retracting step in response to the generation of a predetermined number of said second signals spaced in time as corresponding to a predetermined frequency.

6. The method of claim 1, further comprising the step of

repeating said interrupting, moving and retracting steps after an elapse of time intervals depending upon the nature of material to be comminuted.

7. The method of claim 1, further comprising the step of

terminating said retracting step as a function of the desired size of comminuted material.

8. The method of claim 1 of operating a comminuting machine, wherein in the absence of material the machine generates the first sound representing running without load and having the first sound intensity less than said second predetermined intensity, and further comprising the steps of

monitoring the sounds;

generating said first signals in response to detection of first sounds having a predetermined first intensity;

generating second signals in response to detection of sounds having said second intensity;

utilizing said second signals to interrupt said moving step; and

utilizing said first signals to terminate a delay period set after said second signal is received.

9. The method of claim 1 of operating a comminuting machine, wherein the second tool assumes an inoperative position and to thus increases said clearance in response to admission of material having a predetermined hardness, further comprising the step of

monitoring the position of said second tool and blocking said moving step when said second tool assumes said inoperative position.

10. A comminuting machine, particularly an impact crusher, comprising

a housing having an inlet for material to be comminuted therein;

a first tool movably mounted in said housing and having a plurality of beaters;

drive means connected with said first tool to move said beaters in said housing along a predetermined path;

a second tool movably mounted in said housing adjacent said path and together with said first tool defining a clearance;

moving means operable to move said second tool relative to said first tool to thus vary the width of said clearance; and

control means including

means for generating first signals denoting the first intensity of said first sound which is generated by the machine running in the absence of material to be crushed;

means for generating second signals denoting the second intensity of second sounds which are generated when the width of said clearance is zero so that said beaters strike said second tool;

electronic means for separating one of said first signals from one of said second signals; and

means for operating said moving means in response a first signal to reduce the width of said clearance and thereupon in response to a second signal to increase the width of said clearance to a predetermined value.

11. The machine of claim 10, wherein said means for generating said first and second signals comprises

a microphone having an output for electric signals dependent on a monitored intensity of said first and second sounds;

means for amplifying said electric signals;

a first threshold circuit connected with said amplifying means and having an output for said first signals connected with said operating means; and

a second threshold circuit connected with said amplifying means and having an output for said second signals connected with said operating means.

12. The machine of claim 11, wherein said operating means includes a computer and a time discriminator for said first and second signals.

13. The machine of claim 11, further comprising a time delay circuit means connected between the output of at least one of said threshold circuits and said operating means.

14. The machine of claim 10, wherein said operating means comprises

means for effecting a movement of the second tool away from said first tool in response to reception of a predetermined number of second signals.

15. The machine of claim 10, wherein said operating means includes means for initiating resumption of admission of material into said inlet in response to widen said clearance to said predetermined value.

16. The machine of claim 10, wherein said second tool includes an impact member and a cushion which yields to permit a movement said member to an inoperative position in response to penetration into said clearance of a material having a predetermined hardness, said control means further comprising means for monitoring the position of said member and for preventing operation of said moving means in a direction to reduce the width of said clearance in said inoperative position of said member.

17. Method for the operation of a comminuting machine, which comprises

associating a first rotating comminution tool with at least a second comminution tool,

adjusting the second comminution tool in its position relative to the first rotating comminution tool,

forming an adjustable grinding gap between the first rotating comminution tool and the second comminution tool,

performing a forward motion at certain time intervals with the second comminution tool for avoiding substantial changes of the grain size of the comminuted material by a drive in an empty-running comminution machine toward said first rotating comminution tool up to a first contact with said first rotating comminution tool,

performing a reversal motion with said second comminution tool to result in a desired distance from said first rotating comminution tool after observation of a noise caused by the first contact between said first rotating comminution tool and said second comminution tool which is made perceptible by a microphone,

automatically determining the motion of the second comminution tool with a computer for a start of the forward motion, for a starting point in time of a reversal motion, and at an end of the reversal motion,

switching on the drive of the second comminution tool to therefore initiate the motion of the second comminution tool toward the first rotating comminution tool if

(a) a first signal reaches the microprocessor, said signal is generated after a switching off of a feeding of material and said signal is fed with a delay to the computer that upon reaching the computer, the comminution machine has been emptied of material to be processed, and

(b) a second signal reaches the microprocessor, said second signal originates from a microphone furnished at a casing of the comminution machine and said second signal, upon filtering a third signal generated by the general running noises, results in a second filtered signal essentially generated only by hard noises which result from the contacting of said second comminution tool with said first rotating comminution tool,

(c) the third signal reaches the microprocessor, said third signal originates from a microphone disposed at the casing of the comminution machine and said third signal is generated by the general noises of the running of the comminution machine under a load,

wherein the microprocessor reverses the motion of said second comminution tool and stops the motion of the second comminution tool after a certain distance which is calculated from the reversal position.

18. Method according to claim 17, further comprising

immediately stopping the motion of the second comminution tool toward the first comminution tool upon occurrence of said filtered second signal, generated by said hard noises, and

wherein the motion is picked up again if no further said filtered second signals follow, and

wherein the motion is reversed, if a certain strength and length or a certain minimum number of said filtered second signals are received within a certain time unit which indicates to the microprocessor the mutual contacting of the comminution tools.

19. Method according to claim 17, further comprising

deriving said second signal and said third signal from one and the same microphone by distribution each of said second signal and said third signal from the microphone after amplification to two separate channels.

20. The method according to claim 17, further comprising

employing an impact mill as a comminution machine, wherein the impact mill includes

a rotor equipped with impact bars and at least an impact plate coordinated to the rotor, whereby the impact plate is adjustable relative to the rotor and forms a grinding gap with the rotor,

wherein moving the impact plate toward the rotor at certain time intervals by way of a drive up to the first contact with the impact bars of the rotor in an empty-running impact mill, in order to avoid substantial changes of the granulometry of the comminuted material by reversing the motion, of the impact plate is brought to the desired distance for operating relative to the rotor, based on said noise resulting from the contact made recognizable by a microphone, wherein a control of the motions of the impact plate, includes the start of the forward motion, the point in time of the reversal motion, and the end of the reversal motion, are automatically performed by a microprocessor, wherein the microprocessor switches on the drive of the impact plate and thereby initiates the motion of the impact plate toward the rotor, if

(a) a switching signal is obtained by the microprocessor, said switching signal is generated by the switching off of the material feed and is delivered with a delay to the microprocessor that the impact mill has been emptied when said switching signal reaches the microprocessor, and

(b) said third signal is obtained by the computer, said third signal originates from a microphone furnished at the casing of the impact mill and said third signal is generated by the general running noises of the impact mill, and

wherein the microprocessor reverses the motion of the impact plate and stops the motion of the impact plate after a certain distance, calculated from the reversal position if

(c) said second signal is obtained by the microprocessor, said second signal originates from the microphone which is furnished at the casing of the impact mill and said second signal by filtering said third signal which is generated by the general running noises, is generated from the hard noises as a result of the contact between impact plate and the impact bars.

21. Method according to claim 20, further comprising

immediately stopping the motion of said second comminution tool, which operates as an impact plate toward said first comminution tool upon occurrence of said filtered second signal, generated by said hard noises, and wherein the motion is picked up again if no further said filtered second signals follow, and

wherein the motion is reversed, if a certain strength and length in a certain time unit indicates to the microprocessor the mutual contacting of said comminution tools.

22. Method according to claim 20, further comprising

determining time intervals with said microprocessor by an exchangeable program furnished for a specific material to be comminuted and coordinated to said microprocessor, during said time intervals a readjustment of the impact plate occurs where said microprocessor initiates the material feed is stopped before the material feed is restarted, respectively.

23. Method according to claim 20, wherein the microprocessor determines the distance of the impact plate to the rotor depending on a desired grain structure by an influenceable program coordinated to said microprocessor, and said microprocessor performs automatically a setting of the impact plate and thus of said grinding gap.

24. Method according to claim 20, further comprising deriving said first signal and said second signal from one and the same microphone by distributing each of said first signal and said second signal from said microphone after amplification to two separate channels.

25. Method according to claim 20 for impact mills, further comprising

operating the drive of the impact plate with an elastic intermediate member, said elastic intermediate member allows an escaping of the impact plate at any time when non- comminutable parts have passed into said impact mill, and wherein

the drive is stopped during the forward motion, if said elastic intermediate member is pressed together from a drive side because of a jamming of a rebound works.

26. An apparatus for automatically adjusting a grinding gap of a comminuting machine for determining the grain size, comprising

a first rotating comminution tool and

at least a second comminution tool furnished with drive aggregates for positional adjustment, wherein said second comminution tool can be adjusted by said drive aggregates relative to said first rotating comminution tool, and

a microphone disposed in a casing of the comminution machine;

a microphone amplifier (19) connected to said microphone (18);

a channel transmitting an amplified signal which comes from the microphone (18) and is subdivided into two channels (21,22), wherein a first channel is led via a first signal decoupler (23) with a low trigger threshold, and wherein a second channel is led via a second signal decoupler (24) with a high trigger threshold to a microprocessor (27),

wherein said microprocessor (27) is programmed to switch on the drive aggregates to sense the approaching of said second comminution tool to said first rotating comminution tool and upon receiving a time-delay signal derived from the switching off of the material feed,

wherein said microprocessor reverses this motion as soon as a second signal reaches said microprocessor which surpasses said high trigger threshold in a certain strength and said second signal is of a longer time duration, wherein said microprocessor stops the reverse motion based on a program entered into said microprocessor, and said microprocessor reinitiates the feeding of material into said comminuting machine.

27. Apparatus according to claim 26, wherein time switches (25, 26) are connected to said signal decouplers (23, 24), and

wherein said time switches (25, 26) can be triggered at a later point in time.

28. An apparatus for automatically adjusting an impact plate of an impact mill comprising

an impact plate;

a casing of the impact mill;

a drive aggregate for said impact plate, said drive aggregate impact plate can be adjusted relative to a rotor impact circle;

a microphone disposed in said casing of said impact mill;

amplifiers (19,

     20) connected to said microphone (18);

a channel transmitting an amplified signal comes from said microphone (18) and is subdivided into two channels (21,

     22), of which said two channels (21,

     22) includes a first channel that leads to a first signal decoupler (23) with a low trigger threshold, and a second channel that leads to a second signal decoupler (24) with a high trigger threshold to a microprocessor (27) wherein said microprocessor (27) is programmed to receive a time-delay signal derived from the switching off of the material feed, said microprocessor switches on said drive aggregate (10,

     11) when said impact plate (5,

     7) approaches said rotor impact circle (8), wherein

said microprocessor reverses this motion as soon as a second signal reaches said microprocessor in a repeated successive sequence, and said second signal surpasses said high trigger threshold, wherein said microprocessor stops the reverse motion based on a program entered into the microprocessor, and wherein said microprocessor reinitiates the feeding in of material into the impact mill.

29. Apparatus according to claim 28, wherein time switches (25, 26) are connected to said signal decouplers (23, 24), and

wherein said time switches (25, 26) can be triggered at a later point in time.

30. Apparatus according to claim 28, wherein switching elements (15, 16) are furnished as part of the elastic intermediate member (13) and are movable with respect to each other, wherein upon compression at said intermediate member (13), said switching elements (15, 16) change their switching state from a drive side to generate said second signal, said second signal stops the drive motion of said impact plate (5, 7) via said microprocessor (27), and modifies the drive motion of said impact plate (5, 7), respectively into a repeated short backward and forward motion until said switching state of said switching elements (15, 16) no longer exist.

31. A method for operating a comminuting machine comprising

moving a second comminuting tool in a forward direction by a drive toward a first rotating comminution tool up to a first contact with said first rotating comminution tool in an empty-running comminution machine for avoiding substantial changes of the grain structure of the comminuted material, wherein said second comminution tool is coordinated to said first rotating comminution tool, wherein said second comminution tool adjustably disposed in its position relative to a position of said first rotating comminution tool, wherein a motion of said second comminution tool is automatically controlled with a microprocessor, wherein said first rotating comminution tool and said second comminution tool form an adjustable grinding gap;

receiving a switching signal in the microprocessor, said switching signal is generated by a switching off of a feeding of material and said switching signal is fed with a delay to said microprocessor that reaches the microprocessor and the comminution machine has been emptied of material to be processed;

receiving a first signal in said microprocessor, wherein said first signal originates from a microphone disposed in the casing of said comminution machine and said first signal is generated by the general noises of the running of the comminution machine;

switching on a drive of said second comminution tool via the microprocessor to initiate a forward motion of said second comminution tool toward said first rotating comminution tool to define a starting time of said forward motion;

generating a second signal with the microphone member in the casing of the comminution machine and feeding said second signal to said microprocessor, wherein said second signal is filtered and separated from said first signal generated by the general running noises, wherein said second signal is essentially generated only by said hard noises, which result upon the contacting of the second comminution tool contacts the first rotating comminution tool;

initiating a reverse motion of said second comminution tool via said microprocessor to obtain a desired distance of said second comminution tool from the first rotating comminution tool after observing said noise caused by the contact of said first comminution tool with said second comminution tool which is made perceptible by said microphone;

calculating a stop position based on the reversal position with said microprocessor;

stopping the reverse motion of said second comminution tool after a certain distance has been covered with said microprocessor.

32. The method according to claim 31 further comprising

operating said second comminution tool as an impact plate toward said first comminution tool;

stopping the motion of said second comminution tool immediately upon occurrence of a filtered second signal, generated by the hard noises; and

picking up the motion again if no further filtered signals follow said filtered second signal; and

reversing the direction if the features of said filtered second signal in a certain time unit indicate to said microprocessor a mutual contacting of said comminution tools.

33. The method according to claim 31 further comprising deriving said first signal and said second signal from said microphone serving simultaneously as a microphone member;

amplifying said first signal and the second signal delivered by said microphone;

distributing each of said first signal and said second signal delivered by said microphone after amplification into two separate channels.

34. The method according to claim 31 further comprising

adjusting an impact plate means relative to a rotor which is part of said first comminution tool in a comminution machine furnished as an impact mill for providing a desired grinding gap, wherein said impact mill includes said first comminution tool equipped with impact bars and said impact plate means furnishes said second comminution tool and is coordinated to said rotor;

moving said impact plate means toward said rotor at certain time intervals by said drive up to said first contact of said impact bars of the rotor in an empty-running impact mill in order to avoid substantial changes of the granulometry of the comminuted material;

bringing said impact plate means to a desired distance relative to the rotor for reversing the direction of the motion based on said noise resulting from the contact between said impact plate means and said impact bars which is made recognizable by said microphone member;

automatically controlling any motion of said impact plate means with a microprocessor which includes a start of a forward motion, a point in time of a reversal motion, and an end of the reversal motion;

feeding said switching signal to said microprocessor, wherein said switching signal is generated by the switching off of the material feed and wherein the switching signal is delivered with a delay to said microprocessor so that said impact mill has been emptied when the switching signal reaches said microprocessor;

feeding said first signal to said microprocessor, wherein said first signal originates from said microphone furnished in said casing of said impact mill and said first signal is generated by the general running noises of the impact mill;

switching said drive of said impact plate means on with said microprocessor to initiate said motion of said impact plate means toward said rotor;

feeding said second signal to said microprocessor, wherein said second signal originates from said microphone furnished in said casing of said impact mill and said second signal, which is filtered and separating from said first signal that is generated by the general running noises, is generated from said hard noises which is the result of the contacting between said impact plate means and said impact bars;

reversing the motion of said impact plate means with said microprocessor;

calculating a stop position of said impact plate means based on the reversal position of the impact plate means with the microprocessor;

stopping the motion of said impact plate means after a certain distance corresponding to said calculated stop position.

35. The method according to claim 34 further comprising

immediately stopping the motion of the second comminution tool toward the first comminution tool when said filtered second signal that is generated by a hard noise occurs;

resuming the motion of said second comminution tool toward said first comminution tool again if no further filtered second signals are following;

reversing the motion of said second comminution tool toward said first comminution tool if certain features of said filtered second signal within a certain time unit indicate to said microprocessor an occurrence of a mutual contacting of said comminution tools.

36. The method according to claim 34 further comprising

feeding microprocessor instructions which forms a program to said microprocessor for determining time intervals to be furnished for performing a readjustment of said impact plate means for a specific exchangeable material to be comminuted and coordinated to said program, and wherein said microprocessor initiates the stopping of the material feed before performing said readjustment and then the material feed is restarted respectively, after performing said readjustment.

37. The method according to claim 34 further comprising

determining the distance of said impact plate means to said rotor with said microprocessor depending on a desired grain structure with a program entered into said microprocessor;

setting a position of said impact plate means to set the grinding gap automatically by using an output of said microprocessor.

38. The method according to claim 34 further comprising

deriving said first signal and said second signal from said microphone;

amplifying said first signal and said second signal delivered by the microphone;

distributing said first signal and said second signal delivered to said microphone after amplification into two separate channels.

39. The method according to claim 34 further comprising

driving said impact plate means of the impact mill with an elastic intermediate member;

allowing resilient retraction of said impact plate means when non-comminutable parts have passed into said impact mill based on the elastic properties of said elastic intermediate member;

stopping said drive during the forward motion, if said elastic intermediate member is pressed together from the drive side because of a jamming of a rebound works.

40. Automatically adjusting a grinding pag of a comminution machine by determining the grain size of the output of the comminution machine comprising

a casing of the comminution machine;

a first rotating comminution tool;

a second comminution tool;

a drive aggregate for a positional adjustment of said second comminution tool, wherein the position of said second comminution tool can be adjusted by said the drive aggregates relative to the position of siad first rotating comminution tool;

a microphone disposed in the casing of said comminution machine;

a microphone amplifier having an output and connected to an output port of said microphone;

a first signal decoupler with a low trigger threshold having an output and having an input connected to said output of the amplifier and forming a first signal channel;

a second signal decoupler with a high trigger threshold having an output and having an input connected to said output of said amplifier and forming a second signal channel, thus subdividing an amplified signal coming from said microphone into two separate channels;

a feed means for the material to be processed in said comminution machine;

a switch connected to said feed means for turning said feed means on or off and said switch having an input;

signal means furnishing a switching signal when said feed means is switched off;

a microprocessor having a first input connected to said output of said first signal decoupler having a low trigger threshold and having a second input connected to said output of said second signal decoupler having a high trigger threshold, said microprocessor having a third input connected to said signal means, said microprocessor having a first output connected to said drive aggregate and having a second output connected to said switch,

wherein said microprocessor is programmed with a program to switch on said drive aggregate to sense the movement of said second comminution tool toward said first rotating comminution tool upon receiving a time-delay signal derived by said signal means which indicates that said feed means is switched off, wherein said microprocessor reverses a direction of motion for moving said second comminution tool away from said first comminution tool as soon as a second signal reaches said microprocessor wherein said second signal surpasses said high trigger threshold in a certain amount and wherein said second signal is of a longer time duration, wherein said microprocessor stops the movement of said second comminution tool away from said first comminution tool based on the program entered into said microprocessor, and said microprocessor reinitiates the feeding of material into said impact mill by sending a corresponding signal to said switch.

41. The comminuting machine according to claim 40 further comprising

a first time delay circuit having an input connected to said first signal decoupler having said low trigger threshold and having said output connected to said first input of said microprocessor for delivering a first trigger signal after a frist delay time;

a second time delay circuit having an input connected to said second signal decoupler having said high trigger threshold and having said output connected to said second input of said microprocessor for delivering a second trigger signal after a second delay time.

42. An impact mill for automatically adjusting an impact plate comprising

a casing of the impact mill;

a rotor;

an impact plate;

a drive aggregate attached to said impact plate for adjusting the position of said impact plate relative to an impact circle of said rotor;

a control switch associated with said drive aggregate for controlling the operation of said drive aggregate;

a microphone having an output and disposed in the casing of the impact mill;

an amplifier having an output and an input connected to said output of said microphone;

a first signal decoupler with a low trigger threshold having an ouput and an input connected to said output of the amplifier;

a second signal decoupler with a high trigger threshold having an output and an input connected to said output of said amplifier, whereby an amplified signal, coming from said microphone is subdivided into two channels with a first channel formed by said first signal decoupler with said low trigger threshold, and with a second channel formed by said second signal decoupler with said high trigger threshold;

feed means for feeding material into said impact mill;

signal means associated with said feed means for indicating if said feed means is in an on or off state;

a microprocessor having a first input connected to said ouput of said first signal decoupler having said low trigger threshold, and a second input connected to said output of said second signal decoupler having said high trigger threshold, said microprocessor having a third input connected to said signal means and said microprocessor having a first output connected to said control switch and a second output connected to said feed means,

wherein said microprocessor is programmed with a program to receive a time-delay signal derived from said signal means indicating a switching off of the material feed, said microprocessor switches on said drive aggregate when said sense of the impact plate moves toward said impact circle of said rotor, said microprocessor initiates the switch when said sense of said impact plate moves away from said impact circle of said rotor as soon as a signal is derived from said microphone that reaches said microprocessor in a repeated successive sequence, and said signal surpasses said high trigger threshold, wherein said microprocessor stops the motion when said said impact plate moves away from said impact circle of said rotor based on said program entered into said microprocessor, and wherein said microprocessor reinitiates the material feed-in by sending a corresponding signal to said feed means.

43. The impact mill according to claim 42 further comprising

a first time delay circuit having an input connected to said first signal decoupler having said low trigger threshold and having said output connected to said first input of said microprocessor for delivering a first trigger signal after a first delay time;

a second time delay circuit having an input connected to said second signal decoupler having said high trigger threshold and having said output connected to said second input of said microprocessor for delivering a second trigger signal after a second delay time.

44. The impact mill according to claim 42 further comprising

an elastic intermediate member having a first part and a second part and disposed between said drive aggregate and said second comminuting tool, wherein said first part and said second part are movable relative to each other;

a switching element connected to said microprocessor and furnished at said first part and at said second part of said elastic intermediate member which are movable relative to each other,

wherein said switching element changes its switching state from the drive side upon comprising at said intermediate member and to generates said second signal fed in to said microprocessor, whereupon said microprocessor stops the motion of said impact plate toward said impact circle of said rotor and wherein said microprocessor modifies the drive motion of said impact plate until a point in time where said switching state upon compression of said switching element no longer exists.

45. The impact mill according to claim 42 further comprising

a reversible electric motor;

a worm drive gear connected to said reversible electric motor;

a spindle disposed substantially radially of said rotor and driven by the worm drive gear;

an elastic cushion;

a lug connecting said elastic cushion to said second comminuting tool.