GB2030287A - Determining the energy expended in grinding - Google Patents
Determining the energy expended in grinding Download PDFInfo
- Publication number
- GB2030287A GB2030287A GB7925737A GB7925737A GB2030287A GB 2030287 A GB2030287 A GB 2030287A GB 7925737 A GB7925737 A GB 7925737A GB 7925737 A GB7925737 A GB 7925737A GB 2030287 A GB2030287 A GB 2030287A
- Authority
- GB
- United Kingdom
- Prior art keywords
- grinding
- members
- sample
- grinding members
- speed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/02—Food
- G01N33/10—Starch-containing substances, e.g. dough
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- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Medicinal Chemistry (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Sampling And Sample Adjustment (AREA)
- Crushing And Grinding (AREA)
Abstract
A method of automatically providing an indication of the milling energy required to grind a predetermined amount of a sample of material, e.g. a barley cultivar, in a grinding mill having grinding members rotatable within a grinding chamber comprises obtaining first and second electrical signals representative of the rotational speeds of the grinding members at two instants of time, a known period of time apart, in the grinding operation. The speed of the grinding members is measured by a photoelectric displacement encoder 8, 9, monitoring the passage of holes in a flywheel 6 driven with the grinding mill. The slowing down of the flywheel due to friction is first measured without a sample. Subsequently, the slowing down due to friction and energy for grinding is measured with a sample present. A microprocessor performs the required calculations. <IMAGE>
Description
SPECIFICATION
Apparatus and method for obtaining an indication of the energy expended in grinding a sample of material
This invention relates to a method of, and apparatus for, automatically providing an indication of the milling energy required to grind a predetermined amount of material in a grinding mill. In particular, but not exclusively, the inventior may be employed in testing different samples of barley cultivars, the indications of the milling energy required to grind the different samples being used to predict the malting quality of the different samples of barley cultivars.
According to one aspect of the invention, a method of automatically providing an indication of the milling energy required to grind a predetermined amount of material in a grinding mill having grinding members rotatable within a grinding chamber, comprises bringing the grinding members to an appropriate rotational speed, introducing a predetermined amount of material to the grinding chamber, obtaining first and second electrical signals representative of the rotational speeds of the grinding members respectively at two instants of time a known period apart in the grinding operation, feeding said electrical signals to electric logic means and obtaining directly from said logic means an electrical signal representative of the energy expended in grinding the sample during said period.
Suitably the first electric signal is obtained when the grinding members rotate at a predetermined speed.
Preferably inertia means, e.g. a flywheel, is associated with the grinding members and provides the energy required to maintain rotation of said grinding members during said period.
Typically the inertia means is coupled to a shaft extending externally of the mill and to which the grinding members are connected. Suitably the speed of rotation of the inertia means (flywheel) is sensed directly for providing said first and second electric signals, the speed of rotation of the inertia means being representative of the speed of rotation of the grinding members.
Preferably, the grinding members and, when provided, the inertia means are accelerated to said appropriate speed with the aid of a motor, e.g. an a.c. commutator motor. Suitably, the drive provided by said motor is automatically disconnected from the grinding members when the latter are rotating at a predetermined uniform speed.
Although the predetermined amount of material may be introduced into the grinding chamber immediately prior to said period, it is preferred that the material is introduced into the grinding chamber during the said period or at the beginning of the said period (i.e. at the same time as the first electric signal is being obtained).
In order to account for frictional losses occurring in the grinding mill it is preferable, as an initial step in the method according to the
invention, to ascertain the frictional losses occurring in the grinding mill when the grinding members are rotated with no material in the grinding chamber. This initial step comprises bringing the grinding members to said appropriate rotational speed, obtaining third and fourth electric signals representative of the rotational speeds of the grinding members at two instants of time the said known period apart, and feeding the third and fourth electrical signals to said electric logic means. The said first electrical signal is subsequently obtained when the grinding members rotate at the same speed as when the said third electrical signal was obtained.
One or more further electrical signals representative of the rotational speed(s) of the grinding members may be obtained after the end of, and at a predetermined time after the commencement of, the said known period, the one or more said further electrical signals being supplied to the logic means for obtaining one or more further electrical signals representative of the energy expended in grinding the sample in one or more periods subsequent to the said known period.
The logic means, which typically comprises a micro-processor, may be programmed to indicate a fault in the apparatus if the grinding members do not attain said appropriate rotational speed. When an initial step is performed for ascertaining frictional losses in the apparatus, a fault may also be indicated if the frictional losses are greater than a predetermined value.
Conveniently, the logic means may be programmed to identify specific types of material on the basis of the energy expended in grinding a particular sample.
Suitably the grinding chamber is cleaned out, e.g. by passing compressed air through, after the grinding of a sample and prior to the introduction of a further sample into, the grinding chamber.
Conveniently the grinding mill is a microhammer mill comprising a cylindrical housing, lined with an abrasive liner, and hammers connected to a shaft mounted centrally within said housing, the hammers being flailed within the housing on rotation of the shaft. Suitably an automatically operated sample release is provided for introducing the material into the grinding chamber.
According to another aspect of the invention, an apparatus for automatically providing an indication of the milling energy required to grind a predetermined amount of a sample of material, comprises a grinding mill having a grinding chamber, grinding members rotatable within the grinding chamber, and means for delivering the sample of material to be ground to the grinding chamber, means for rotating the grinding members, means for sensing, and providing first and second electrical signals representative of, the rotational speeds of the grinding members at two instants of time a known period apart in the grinding operation, and electric logic means having an input connected to said sensing means
and an output for providing an electrical signal
representative of the energy expended in grinding
a sample of material during the said known period.
The invention will now be described by way of
example with reference to the accompanying
drawings, in which: Figure 1 is a schematic side view of apparatus
for grinding material in a grinding mill, and
Figure 2 is an electrical block diagram for
controlling the apparatus shown in Figure 1.
Figure 1 shows a microhammer mill 1 comprising a cylindrical housing 2 internally lined with an abrasive liner (not shown) and defining a grinding chamber. Flailing hammers (not shown) are mounted on a central drive shaft 3.
The mill 1 is provided with a delivery hopper 4 for supplying a predetermined weight of
material, e.g. barley or other grain samples, automatically and as quickly as possible to the centre of the grinding chamber, and an outlet b having a removable gna (not shown) fixed therein through which the resulting ground material is passed. Such a microhammer mill 1 can be purchased from Glen Creston
Company Limited.
The drive shaft 3 has a flywheel 6 coupled thereto and is driven by an a.c. commutator motor 7 designed to operate at a speed of 5,600 revolutions per minute. The flywheel 6 has a plurality of holes (not shown) equaily spaced apart and located at an equal distance from the axis cf the shaft 3. These hoies form part of an optical sensing system, comprising a light source 8 and light sensor 9, for sensing the speed of rotation of the flywheel 6 and providing gating pulses to a crystal clock (not shown).
The apparatus shown in Figure 1 is automatically controlled by a digital microprocessor 10 (see Figure 2).
In operation, the microprocessor 10 controls the operation of the apparatus shown in Figure 1 as follows:- 1. The motor 7 is energised and runs up to speed causing the flywheel 6, the shaft 3 and the flailing hammers to rotate at a speed of 5,600
RPM.
2. The power to the motor is automatically switched off either when the motor is running at full speed - in which case the speed of rotation , of the flywheel 6 is then sensed by the optical sensing system - or when the optical sensing system senses that the flywheel 6 is rotating at a predetermined speed cl)1. The speed c91 is stored in the memory of the microprocessor 1 0.
3. The flywheel 6 slows down due to friction losses in the apparatus.
4. After a time t, has elapsed from the switching off of the motor 7, the speed of rotation bt)2 of the flywheei 6 is sensed by the optical sensing system and stored in the memory of the microprocessor 10.
5. The motor 7 is then re-energised and runs up to speed (5600 RPM).
6. When the motor 7 is running at full speed or when the optical sensing system senses that the flywheel 6 is rotating at a predetermined speed the following events occur simultaneously or in
quick succession in any order: a) The motor 7 is switched off,
b) A predetermined weight of sample material is automatically supplied to the grinding chamber of the mill 1, and c) The speed of rotation w3 of the flywheel 6 is sensed by the optical sensing system and is stored in the memory of the microprocessor 10.
7. The flywheel 6 slows down due to frictional losses in the apparatus and due to the energy required to grind the sample of material in the mill.
8. After time t, has elapsed from switching off the motor 7 (step 6a), the speed of rotation 4 of the flywheel is sensed by the optical sensing system and stored in the memory of the microprocessor 10 (typically eo4 is 5080% of a)3).
9. The milling energy, M, required to mill the material in the mill is processed in the microprocessor from the formula M=-21K[(32-w42)-(w12-22)]' where K is the moment of inertia of the flywheel 6 (which is known or can be calculated).
10. The milling energy calculated in the microprocessor 10 is stored in the memory and/or displayed on a screen (not shown), printed on a printer 20 (see Figure 2), recorded on a recorder (not shown), or transmitted to external means for processing, recording or display.
In the process just described the microprocessor 10 gives an indication of the energy required to grind a sample of material over a single time period t,. In other embodiments of the invention it is possible to measure or give an indication of the energy required to grind further a sample of material in one or more further time periods after the time period t,. The first time period measurement is intended to indicate the main energy parameter which provides the basis for inter-sample comparisons and the second or subsequent time period(s) is (are) used over the 'ta77-otf' period of the measurement and is intended to show any additional unique sample characteristics. Typically the time period(s) can be adjustably set from 1 to 10 seconds.
It should be realised that the predetermined period(s) and predetermined rotational speeds of the flywheel 6 can be simply adjusted by altering manually inputs to the microprocessor 1 0.
Furthermore it should be realised that it is not essential to perform all the steps of the process outlined above. For example it is possible to perform the process without measuring the frictional loss of the apparatus (frictional losses could be estimated or ignored completely).
It is also feasible to provide a sample recognition feature for the apparatus. With this feature the processor is able to recognise a sampled material on the basis of the known grinding characteristic of the material which is previously manually fed into the memory of the microprocessor 10.
In Figure 2 there is shown a block diagram showing generally how the apparatus shown in
Figure 1 is controlled. In Figure 2 the elements 11, 12, 13, 14 and 15 are peripheral interface adaptors, element 1 6 represents circuitry for indicating any fault in the apparatus (e.g.
predetermined speeds of rotation of flywheel not attained or friction too great) and for controlling the energising of the motor 7, elements 1 7 and 18 represents clocks for timing two measuring periods (these periods being adjustable), element 1 9 represents an arithmetic unit (a so-called "number cruncher"), element 20 represents a printer for printing out results calculated by the microprocessor 10, element 21 represents switches for feeding in information pertaining to a particular material for enabling sample recognition, elements 22 and 23 represent elements of the optical speed sensing system, and element 24 represents a buffer enabling the input and output of information to and from the microprocessor 1 0.
Finally further features of the invention enable the microprocessor 10 to control compressed air cleaning of the mill to clear away remnants of material left in the mill prior to arrival of a new sample of material in the mill.
It should also be realised that the invention is not limited to the testing of barley cultivars. The invention may be applied generally in materials study where the accuracy and speed of measuring the energy required to degrade a material may produce further valuable correlations.
Claims (34)
1. A method of automatically providing an indication of the milling energy required to grind a predetermined amount of a sample of material in a grinding mill having grinding members rotatable within a grinding chamber, comprises bringing the grinding members to an appropriate rotational speed, introducing a predetermined amount of the sample of material to the grinding chamber, obtaining first and second electrical signals representative of the rotational speeds of the grinding members respectively at two instants of time a known period apart in the grinding operation, feeding said electrical signals to electric logic means and obtaining directly from said logic means an electrical signal representative of the energy expended in grinding the sample during said period.
2. A method according to claim 1, in which the first electric signal is obtained when the grinding members rotate at a predetermined speed.
3. A method according to claim 1 or 2, in which the energy required to maintain rotation of said grinding members during the said period is provided at least partly by inertia means, e.g. a flywheel, associated with the grinding members.
4. A method according to claim 3, in which the inertia means is coupled to the grinding members and the speed of rotation of the inertia means (flywheel) is sensed directly for providing said first and second electric signals, the speed of rotation of the inertia means being representative of the speed of rotation of the grinding members.
5. A method according to claim 4, in which the speed of rotation of the inertia means is sensed by a photoelectric system.
6. A method according to any of the preceding claims, in which the grinding members are accelerated to said appropriate speed with the aid of a motor.
7. A method according to claim 6, in which the logic means provides a control signal for automatically disconnecting the drive between the motor and the grinding members when the latter are rotating at a predetermined uniform speed.
8. A method according to any of the preceding claims, in which the predetermined amount of the sample of material is introduced into the grinding chamber immediately prior to the said period.
9. A method according to any of claims 1 to 7, in which the said predetermined amount of said sample of material is introduced into the grinding chamber during the said period or at the beginning of the said period (i.e. at the same time as the first electric signal is being obtained).
1 0. A method according to any of the preceding claims, comprising, as an initial step, ascertaining the frictional losses occurring in the grinding mill when the grinding members are rotated with no material in the grinding chamber.
11. A method according to claim 10, in which the said frictional losses are ascertained by bringing the grinding members to said appropriate rotational speed, obtaining third and fourth electric signals representative of the rotational speeds of the grinding members at two instants of time the said known period apart, and feeding the third and fourth electrical signals to said electric logic means, the said first electrical signal subsequently being obtained when the grinding members rotate at the same speed as when the said third electrical signal was obtained.
12. A method according to any of the preceding claims, comprising obtaining one or more further electrical signals representative of the rotational speed(s) of the grinding members after the end of, and at a predetermined time after the commencement of, the said known period, the one or more said further electrical signals being supplied to the logic means for obtaining one or more further electrical signals representative of the energy expended in grinding the sample in one or more periods subsequent to the said known period.
13. A method according to any of the preceding claims, in which the logic means is programmed to indicate a fault in the apparatus if the grinding members do not attain said appropriate rotational speed.
14. A method according to claim 10 or 1 1,or claim 12 or 13 when dependent on claim 10 or 11, in which the logic means is programmed to indicate a fault if the said frictional losses are greater than a predetermined value.
1 5. A method according to any of the preceding claims in which the logic means is programmed to identify specific types of material on the basis of the energy expended in grinding a particular sample.
16. A method according to any of the preceding claims, in which the grinding chamber is cleaned out, prior to the introduction therein of a sample of material, preferably under the control of said logic means.
17. A method according to claim 16, in which the grinding chamber is cleaned out by passing compressed air therethrough.
18. A method according to any of the preceding claims, in which the predetermined amount of material is automatically charged into the grinding chamber under the control of said logic means.
1 9. A method according to any of the preceding claims, in which the said sample of material introduced into the grinding chamber is a barley cultivar.
20. A method according to any of the preceding claims, in which the electrical signal obtained from the logic means is supplied to a printing device, a temporary display device, a recording device and/or a processing device.
21. A method according to any of the preceding claims, in which the said period is from 1 to 10 seconds.
22. A method according to any of the preceding claims in which the said period is such that the rotational speed of the grinding members at the later of the said two instants of time is from 50 to 80% of the rotational speed of the grinding members at the earlier of the said two instants of time.
23. A method according to any of the preceding claims, in which the said period is adjustable.
24. A method according to any of the preceding claims, in which the said appropriate rotational speed of the grinding members is adjustable.
25. An apparatus for automatically providing an indication of the milling energy required to grind a predetermined amount of a sample of material, comprises a grinding mill having a grinding chamber, grinding members rotatable within the grinding chamber, and means for delivering the sample of material to be ground to the grinding chamber, means for rotating the grinding members, means for sensing, and providing first and second electrical signals representative of, the rotational speeds of the grinding members at two instants of time a known period apart in the grinding operation, and electric logic means having an input connected to said sensing means and an output for providing an electrical signal representative of the energy expended in grinding a sample of material during the said known period.
26. An apparatus according to claim 25, including inertia means associated with the grinding members for providing the energy required to maintain rotation of said grinding members during the said period.
27. An apparatus according to claim 26, in which the inertia means is coupled to a shaft extending externally of the mill and to which the grinding members are connected.
28. An apparatus according to claim 27, in which the inertia means is a flywheel.
29. An apparatus according to claim 28, in which the said sensing means comprises photoelectric means for sensing the speed of rotation of the flywheel.
30. An apparatus according to claim 29, in which said photoelectric means comprises a plurality of openings provided in the flywheel and equally spaced apart on the circumference of a circle coaxial with the rotational axis of the flywheel, and a light source and a light sensor arranged on opposite sides of the flywheel, the light sensor being arranged to receive only light emitted from the light source and passing through any of the said openings so that in use, when the flywheel rotates, the light sensor is adapted to receive light from the source in the form of light pulses, the light sensor including means for converting the light pulses into electrical pulses.
31. An apparatus according to any of claims 25 to 30, in which the means for rotating the grinding members is an electric motor, e.g. an a.c.
commutator motor
32. An apparatus according to any of claims 25 to 31, in which the logic means is a microprocessor.
33. An apparatus according to any of claims 25 to 32, in which the grinding mill is a microhammer mill having a cylindrical grinding chamber lined with an abrasive liner, the grinding members being in the form of hammers which are mounted on a rotatable shaft mounted axially within the grinding chamber.
34. An apparatus for automatically providing an indication of the milling energy required to grind a predetermined amount of material, the apparatus being constructed and arranged substantially as herein described with reference to, and as illustrated in, Figures 1 and 2 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7925737A GB2030287A (en) | 1978-07-25 | 1979-07-24 | Determining the energy expended in grinding |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7831009 | 1978-07-25 | ||
| GB7925737A GB2030287A (en) | 1978-07-25 | 1979-07-24 | Determining the energy expended in grinding |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2030287A true GB2030287A (en) | 1980-04-02 |
Family
ID=26268333
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7925737A Withdrawn GB2030287A (en) | 1978-07-25 | 1979-07-24 | Determining the energy expended in grinding |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2030287A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5907018A (en) * | 1991-03-20 | 1999-05-25 | Minnesota Mining And Manufacturing Company | Radiation-curable acrylate/silicone pressure-sensitive adhesive coated tapes adherable to paint coated substrates |
| US7559495B2 (en) * | 2004-12-27 | 2009-07-14 | Leonard Coble | Soft start, high inertia flywheel for tub grinders |
| CN103949323A (en) * | 2014-04-18 | 2014-07-30 | 钟俊良 | Energy-saving starting device of crusher |
| CN104455281A (en) * | 2014-11-25 | 2015-03-25 | 广西贺州弘任机械节能科技有限公司 | Balance weight inertia energy saving speed reducer and crusher of balance weight inertia energy saving speed reducer |
-
1979
- 1979-07-24 GB GB7925737A patent/GB2030287A/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5907018A (en) * | 1991-03-20 | 1999-05-25 | Minnesota Mining And Manufacturing Company | Radiation-curable acrylate/silicone pressure-sensitive adhesive coated tapes adherable to paint coated substrates |
| US7559495B2 (en) * | 2004-12-27 | 2009-07-14 | Leonard Coble | Soft start, high inertia flywheel for tub grinders |
| CN103949323A (en) * | 2014-04-18 | 2014-07-30 | 钟俊良 | Energy-saving starting device of crusher |
| CN104455281A (en) * | 2014-11-25 | 2015-03-25 | 广西贺州弘任机械节能科技有限公司 | Balance weight inertia energy saving speed reducer and crusher of balance weight inertia energy saving speed reducer |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |