Method and apparatus for controlling wood pulp grinding machines

Claim 3

A method according to claim 1, wherein said degrees of sharpness are calculated by inserting said power and feed rate values into the following equation: ##EQU5## where n equals the number of pockets, k i =constants for the different pockets, which are dependent upon their geometry and are equal to 1 if all are alike, S i =the degree of sharpness, i designating the assigned ordinal number of each pocket, h i =the feed rates of the pockets, i designating the assigned ordinal number of each pocket, β=an empirical constant close to 0.5, and f i =1 when the pocket is in grinding operation and 0 when it is not, i designating the assigned ordinal number of each pocket.

Claim 4

A method according to claim 2, whereby said equation is used for each of said measuring steps, whereby the number of equations corresponds to the number of measuring steps.

Claim 5

A method according to claim 3, wherein said degrees of sharpness are calculated by simultaneously solving said equations.

Claim 6

A method according to claim 4, wherein in solving said equations an assumption is made that the degrees of sharpness for pockets located at the same grindstone are the same, whereby the number of measuring steps may be cut in half.

Claim 7

A method according to claim 3, wherein at the time of conducting at least one of said measuring steps the feeding pressure in a pocket is altered to obtain a greater independence between said equations, whereby the accuracy in their solution may be increased.

Claim 8

A method according to claim 3, wherein after each calculation of said degrees of sharpness, their mean values are calculated using the present and a specified number of immediately preceding calculations to obtain sliding averages, whereby measuring errors are decreased.

Claim 9

A method according to claim 1, wherein said measuring steps are carried out when the grinding in one of the pockets has been terminated.

Claim 10

A method according to claim 1, wherein the degree of sharpness is determined separately for each pocket, the number of measuring steps corresponding with the number of pockets, whereby it is possible to determine whether the grindstones are sufficiently showered by spray water.

Claim 13

A method according to claim 10, wherein said degrees of sharpness are calculated by inserting said power and feed rate values into the following equation: ##EQU6## where n equals the number of pockets, k i =constants for the different pockets, which are dependent upon their geometry and are equal to 1 if all are alike, S i =the degree of sharpness, i designating the assigned ordinal number of each pocket, h i =the feed rates of the pockets, i designating the assigned ordinal number of each pocket, β=an empirical constant close to 0.5, and f i =1 when the pocket is in grinding operation and 0 when it is not, i designating the assigned ordinal number of each pocket.

Claim 14

A method according to claim 11, wherein said equation is used for each of said measuring steps, whereby the number of equations corresponds to the number of measuring steps.

Claim 15

A method according to claim 12, wherein said degrees of sharpness are calculated by simultaneously solving said equations.

Claim 16

A method according to claim 13, wherein in solving said equations an assumption is made that the degrees of sharpness for pockets located at the same grindstone are the same, whereby the number of measuring steps may be cut in half.

Claim 17

A method according to claim 12, wherein at the time of conducting at least one of said measuring steps the feeding pressure in a pocket is altered to obtain a greater independence between said equations, whereby the accuracy in their solution may be increased.

Claim 18

A method according to claim 12, wherein after each calculation of said degrees of sharpness, their mean values are calculated using the present and a specified number of immediately preceding calculations to obtain sliding averages, whereby measuring errors are decreased.

Claim 19

A method according to claim 10, wherein said measuring steps are carried out when the grinding in one of the pockets has been terminated.

Claim 20

A method according to claim 10, wherein the degree of sharpness is determined separately for each pocket, the number of measuring steps corresponding with the number of pockets, whereby it is possible to determine whether the grindstones are sufficiently showered by spray water.

Claim 21

Apparatus for controlling the operation of a wood pulp grinding machine of the type which has at least two pockets per grindstone and two grindstones coupled by way of a common shaft to a single motor, comprising first generating means for automatically generating a signal in response to the power produced by the motor; second generating means for automatically generating a signal in response to the feed rates of the pockets; calculating means for automatically calculating the degrees of sharpness of the grindstones from the signals generated by said first generating means and said second generating means; and dressing means for dressing each grindstone when its calculated degree of sharpness reaches a determined value.

Claim 22

Apparatus for controlling the operation of a wood pulp grinding machine of the type which has at least two pockets per grindstone and two grindstones coupled by way of a common shaft to a single motor, comprising first generating means for automatically generating a signal in response to the power produced by the motor; second generating means for automatically generating a signal in response to the feed rates of the pockets; calculating means for automatically calculating the degrees of sharpness of the grindstones from the signals generated by said first generating means and said second generating means; and dressing means for dressing each grindstone when its calculated degree of sharpness reaches a determined value.

Claim 23

Apparatus according to claim 19, wherein said first generating means includes a wattmeter electrically connected to the motor.

Claim 24

Apparatus according to claim 19, wherein said second generating means includes a plurality of potentiometers, each of which is mechanically connected to a plunger of a corresponding one of the pockets.

Claim 25

Apparatus according to claim 19, wherein said calculating means is a computer.

Claim 26

Apparatus for controlling the operation of a wood pulp grinding machine of the type which has two grindstones mounted on a single motor shaft, each grindstone being provided with at least two pockets, the grinding in each pocket being done so that the grinding pressure in each pocket is adjusted for a constant feed rate or constant specific energy consumption and the two grindstones are dressed alternately, comprising first generating means for automatically generating a signal in response to the power produced by the motor; second generating means for automatically generating a signal in response to the feed rates of the pockets; calculating means for automatically calculating the degrees of sharpness of the grindstones from the signals generated by said first generating means and said second generating means; determining means for determining a first grindstone to be dressed as a function of the calculated degrees of sharpness of the grindstones; shutting off means for shutting off one pocket of the first grindstone to be dressed for a period of time prior to its dressing; and dressing means for dressing the first grindstone to be dressed when its calculated degree of sharpness reaches a determined value.

Claim 27

Apparatus for controlling the operation of a wood pulp grinding machine of the type which has two grindstones mounted on a single motor shaft, each grindstone being provided with at least two pockets, the grinding in each pocket being done so that the grinding pressure in each pocket is adjusted for a constant feed rate or constant specific energy consumption and the two grindstones are dressed alternately, comprising first generating means for automatically generating a signal in response to the power produced by the motor; second generating means for automatically generating a signal in response to the feed rates of the pockets; calculating means for automatically calculating the degrees of sharpness of the grindstones from the signals generated by said first generating means and said second generating means; determining means for determining a first grindstone to be dressed as a function of the calculated degrees of sharpness of the grindstones; shutting off means for shutting off one pocket of the first grindstone to be dressed for a period of time prior to its dressing; and dressing means for dressing the first grindstone to be dressed when its calculated degree of sharpness reaches a determined value.

Claim 28

Apparatus according to claim 23, wherein said first generating means includes a wattmeter electrically connected to the motor.

Claim 29

Apparatus according to claim 23, wherein said second generating means includes a plurality of potentiometers, each of which is connected mechanically to a plunger of a corresponding one of the pockets.

Claim 30

Apparatus according to claim 23, wherein said calculating means is a computer.

Claim 31

A method according to claim 10, further comprising the steps of shutting off one pocket of the second grindstone to be dressed for a period of time prior to its dressing and dressing the second grindstone to be dressed when its calculated degree of sharpness reaches a determined value.

Claim 32

Apparatus according to claim 23, wherein said shutting off means shuts off one pocket of the second grindstone to be dressed for a period of time prior to its dressing and said dressing means dresses the second grindstone to be dressed when its degree of sharpness reaches a determined value.