GB2052675A

GB2052675A - A Machine for Refining Raw Materials for Making Chocolate

Info

Publication number: GB2052675A
Application number: GB8014720A
Authority: GB
Original assignee: Low & Duff Ltd
Current assignee: Low & Duff Ltd
Priority date: 1979-05-03
Filing date: 1980-05-02
Publication date: 1981-01-28
Also published as: GB2052675B

Abstract

A stationary drum for the material to be refined contains a rotor carrying a series of grinding bars for cooperating with fixed bars on the interior of the peripheral wall of the drum to effect refining, and a toggle device operated by axial movement of a control shaft 10 effects radial adjustment of the grinding bars to increase or decrease the pressure exerted on the material between the two series of bars. In such a machine, adjustment of the toggle device is effected, when required, by means of a reversible auxiliary electric motor which drives a gearbox 14, 15 which, in turn drives a captive nut 18 which engages screw-threads on a non- rotatable thrust shaft 19 to effect axial movement of the latter and, through a coupling 23 and the shaft 10, adjustment of the toggle device. Operation of the auxiliary motor may be effected automatically via an electrical bridge circuit. <IMAGE>

Description

SPECIFICATION A Machine for Refining Raw Materials for Making Chocolate This invention relates to a machine for refining substances, especially raw materials for making chocolate, chocolate compounds and substitutes.

Such machines are known, and consist generally of a substantially horizontal, stationary drum for the material to be refined, a drive shaft driven by an electric motor and projecting axially into the drum and carrying therein a rotor which has a series of radial arms each carrying at its free end a grinding bar extending axially of the drum.

The interior wall of the drumsupports a series of peripherally spaced, axially extending lining bars, and, in use, the grinding bars co-operate with lining bars to refine the material between them as the rotor rotates. The rotor is provided with a toggle device which can be operated to move the grinding bars radially nearer to or farther from the lining bars in order to increase or decrease the pressure exerted on the material between the two series of bars. Such a machine will be referred to hereinafter as a machine of the kind aforesaid.

At present, in a machine of the kind aforesaid, the toggle device is adjustable by an axially movable control shaft which, at one end, is connected to the toggle device and rotates with it.

The shaft has a screw-threaded portion which engages in an internally screw-threaded sleeve.

The sleeve can rotate with the shaft, or can be held against rotation by engagement of a dog clutch or brake to permit the control shaft to rotate relative to the sleeve and thus move axially to adjust the toggle device to effect an increase in the pressure between the grinding and lining bars.

The clutch has to be held in its engaged condition by manually pushing-in a hand wheel.

In order to move the shaft in the opposite direction to reduce the pressure between the bars, it is necessary for the operator to engage the clutch and turn the handwheel in the same direction of rotation as the drive shaft but faster than the speed at which the drive shaft is rotating.

A disadvantage of machines of the kind aforesaid is that it involves a considerable amount of time and labour on the part of personnel to monitor and adjust the pressure aforesaid, especially as there is usually a considerable number of such machines in a chocolate refinery.

An object of the present invention is to provide a machine of the kind aforesaid, in which said disadvantage is obviated or mitigated.

According to the present invention there is provided a machine of the kind aforesaid, in which the said drive shaft carrying the rotor has an axial bore in which said axially movable control shaft is slideably located, the end of the control shaft remote from the toggle device projecting into a gearbox and being coupled to the adjacent end of a non-rotatable thrust shaft which carries a captive gear wheel in screw-threaded engagement therewith, and said gear wheel being driveable, when required, selectively in either direction by a motor via a second gear wheel to effect axial displacement of the thrust shaft and the control shaft, and consequently adjustment of the toggle device and the pressure between the lining bars and the grinding bars.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a sectional view of a machine according to the present invention, the gearbox or pressure adjusting device being shown diagrammatically; Fig. 2 is a iongitudinal sectional view of the gearbox; Fig. 3 is a cross sectional view of the gearbox; Fig. 4 is an end view of the machine, and Fig. 5 is an electrical control circuit diagram.

Referring to the drawings, a machine for refining raw materials for making chocolate consists of a drum 1 for the material; a drive shaft 2 projecting axially into the drum and carrying therein a rotor 3 which has a series of radial arms 4 each carrying at its free end a grinding bar 5 extending axially of the drum 1; a series of peripherally spaced lining bars 6 on the interior face of the peripheral wall of the drum; a toggle device 7 which can be operated to move the grinding bars 5 nearer to or farther from the lining bars 6; an electric motor 8 in driving connection with the shaft 2 via gearing 9; a control shaft 10 for effecting adjustment of the toggle device 7; and control mechanism 11 for the shaft 10.

The drive shaft 2 is hollow, and the control shaft 10 is slideably located within and relative to the drive shaft 2. The inner end of the control shaft 10 is operatively connected to the toggle device 7, and the outer end of the control shaft is operatively connected to the control mechanism 11.

The control mechanism will now be described with reference especially to Figs. 2 and 3.

The control mechanism comprises a speed reduction gearbox 12 and an electric motor 13 mounted thereon. The gearbox has a wormshaft 14 which meshes with a wormwheel 15, is supported on taper roller bearings 16, and is connected at one end by a rigid coupling 17 to the shaft 1 3A of the motor 13. The latter may be a 1.5 h.p. motor, and the speed reduction may be from 1400 r.p.m. to 38 r.p.m., i.e. a ratio of 37 to 1.

The wormwheel 1 5 has opposed axial spigots 1 5A by which it is supported in the gearbox by taper roller bearings 17, and the bore of the wormwheel has a phosphor-bronze sleeve or bush 1 8 secured therein. The wormwheel 1 5 is carried by a shaft 1 9 which passes through the bush 18, and the shaft 19 and the bust 18 have interengaging square threads indicated by chaindotted lines in Fig. 2. An outer end portion of the shaft 1 9 has secured to it a key -1 9A which is a sliding fit in a keyway provided in bronze guide bush 20 which is fixedly located in a tubular holder 21 bolted to a housing 22 secured to the gearbox 12.The inner end of the shaft 19 is connected to the adjacent end of the control shaft 10 by a two-way thrust coupling 23, which consists of a housing 24, thrust bearings 25, 26 and a thrust plate 27 within the housing 24, and a lock plate 28.

In use, the motor 8 drives the shaft 2 to effect the refining action by the bars 5 and 6, and the pressure between these bars can be adjusted by operating the motor 13. When this happens, the motor 13 drives the wormshaft 14 which drives the wormwheel 1 5 and thus the threaded bush 15A. As the wormwheel 1 5 cannot be displaced axially because of the bearings 17, and the thrust shaft 19 cannot rotate because of the key 20, the rotation of the bush 1 8 causes axial displacement of the shaft 1 9 in one direction or the other dependent upon which direction of drive for the motor 1 3 is selected. The axial movement of the shaft 1 9 is transmitted to the control shaft 10 via the coupling 23, and adjustment of the toggle device 7 is thus effected.It will be understood that the control shaft 10 rotates with the shaft 2, but relative to the shaft 19.

The pressure applied between the lining and grinding bars is directly related to the axial position of the thrust shaft 19, and for a predetermined axial movement of the shaft 1 9 there is a proportionate increase or decrease in the pressure being applied between the lining bars and the grinding bars. The total axial movement of the shaft 19 is 60 mm, thus providing pressure adjustment from zero to full pressure, plus an allowance for wear which may take place in the bars 4,6.

The actual axial position of the shaft 1 9 may be indicated by means of an indicator rod (not shown) which is attached to the outer end of the shaft 19 and protrudes through a slot in the end wall of the tubular holder 21, and may be provided with an appropriate scale. Alternatively, the indicator rod may carry an index finger which can be viewed through a window presenting a scale, the window being provided in a control panel 138 (Fig. 4) for the motor 13.

On the control panel 1 3B, there is a push button for the increase pressure direction and a push button for the decrease pressure direction.

The motor 13 only operates when one of the push buttons is held depressed, and stops immediately it is released, or, when the limit of travel is reached in each direction, it stops due to the action of a limit switch, the limit switches being actuated by the pressure indicator rod aforesaid.

In order to attain maximum efficiency of the refining operation, it is desirable that the main motor 8 be kept running under full load. An ammeter is therefore provided, and is electrically connected to the main motor 8 so as to indicate the amount of current being used by the motor during a refining operation. The ammeter is located on or adjacent the control panel 13B so that the operator can easily see if the main motor is operating under full load. If it is operating below full load, the operator depresses the increase pressure button on the control panel, until the ammeter indicates that the motor is again operating under full load. It will normally be necessary for the decrease pressure button to be used only for initial factory adjustment, or at the start of an operation in a refinery.

With a view to simplifying refining operations further, provision is made for automatically operating the motor 13 to increase the pressure between the grinding and lining bars if the main motor 8 runs below full load. Thus, there is provided a bridge circuit as shown diagrammatically in Fig. 4 connecting the main motor 8 with the pressure adjustment motor 13.

During a refining operation, if the main motor 8 is operating under full load, the bridge circuit is balanced, and no current flows to the motor 1 3 via the output terminals 30 of the bridge circuit. If, however, the motor 8 operates at less than full load, i.e. consumes less than full load current, the bridge circuit is unbalanced and current flows to motor 13 so that it is driven to increase pressure between the grinding and lining bars until the main motor 8 again operates at full load. When this happens, the bridge circuit is again balanced, and the motor 1 3 ceases to operate. It is to be understood that the manual control can be used to override the automatic control, though this wouid normally not be necessary except for initially adjusting the pressure between the bars to the minimum required at the start of a refining operation.

In chocolate systems in which there is a group of such refining machines, the controls of the machines can be brought together to a master control desk.

In Fig. 1, the numeral 31 indicates input openings to the drum 1,32 indicates a closeable discharge opening, 33 indicates a water jacket for the drum and 34 indicates an immersion heater, and, in Fig. 4, 35 indicates a flexible coupling between the shaft of the main motor 8 and the worm shaft 9A (Fig. 1) of the gearing 9.

Claims

1. A machine of the kind aforesaid, in which the said drive shaft carrying the rotor has an axial bore in which said axially movable control shaft is slideably located, the end of the control shaft remote from the toggle device projecting into a gearbox and being coupled to the adjacent end of a non-rotatable thrust shaft which carries a captive gear wheel in screw-threaded engagement therewith, and said gear wheel being driveable, when required, selectively in either direction by an auxiliary motor via a second gear wheel to effect axial displacement of the thrust shaft and the control shaft, and consequently adjustment of the toggle device and the pressure between the lining bars and the grinding bars.

2. A machine as claimed in Claim 1, in which a control panel for the auxiliary motor is provided, the control panel having two control buttons which can be held depressed selectively to effect operation of the auxiliary motor in opposite directions of drive.

3. A machine as claimed in Claim 2, in which the main motor for driving said drive shaft is electrically connected to an ammeter for indicating the amount of current being consumed by the main motor, whereby, if the motor is not operating, as is desirable, at full load, this can be seen from the ammeter and the operator can depress the appropriate control button to drive the auxiliary motor to increase the pressure between the grinding and lining bars until the main motor operates at full load.

4. A machine as claimed in Claim 1 or 2 or 3, in which means is provided for automatically effecting operation of said auxiliary motor to effect an increase in pressure between the grinding and lining bars, if the main motor operates below full load, said means comprising a bridge circuit electrically connecting the main motor to the auxiliary motor, the bridge circuit being balanced when the main motor operates at full load so that no current flows to the auxiliary motor, and being unbalanced if the main motor operates below full load so that current flows to the auxiliary motor and the latter is driven to .effect increase in the pressure between the grinding and lining bars until the main motor operates at full load and the bridge circuit is again balanced.

5. A machine as claimed in Claim 1 substantially as hereinbefore described with reference to the accompanying drawings.