GB2029049A

GB2029049A - Electrical Kneading and Mixing Machine

Info

Publication number: GB2029049A
Application number: GB7924798A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-08-23
Filing date: 1979-07-17
Publication date: 1980-03-12
Also published as: BE878375A; IT1121646B; DE2836757A1; NL7905062A; IT7909514A0; GB2029049B

Abstract

An electrically powered kneading and mixing machine operable at various speed settings has a guard which, if raised while the machine is in operation, switches off the machine, and an electronic control system enabling the machine to be programmed to work at different speed settings for different periods of time. The control units for the different speed settings are coupled such that after operation at a lower speed setting for a desired length of time the control unit for the next higher speed setting is automatically actuated. A timing relay may be connected in series with the control unit or units for the or each of the higher speed settings enabling the machine to be run for a predetermined short time at the lowest speed setting if the machine is re-started after being brought to a stand-still whilst working at a higher speed setting. The electronic control system of the described machine provides digital displays of the time for which the machine has been programmed to work at each speed setting and the actual time for which the machine has been working at each setting. Data may be entered by means of a central input keyboard provided with an input memory. Desirably the units of the electronic timing system comprise plug-in modules enabling the control units for various speed settings to be controlled from a central processor.

Description

SPECIFICATION Electrical Kneading and Mixing Machine The invention concerns electrical kneading and mixing machine-sharing various speed settings and which are fitted with guards which, when raised, switch the machines off.

Electically driven kneading and mixing machines with various speed settings are known, German Auslegeschrift No. 1178 803 discloses a bakery machine having two speed settings. A requirement of this type of machine is that the motor be switched off when a guard is raised, and that when the guard is lowered the machine restarts at its lower speed setting so that the maximum possible torque is obtained. The restarting of the kneading and mixing machine in its lower speed setting also necessary to ensure that the starting currents do not exceed certain levels so as to save the electricity supply system from undue exception loads. If this known machine is stopped, by opening the guard, while running at its lower speed, it may be restarted in this speed setting simply by closing the guard.But if the machine is switched off, by opening the guard, while running at its higher speed the guard must be closed and in addition a cam pole reverser must be turned through one switching position to restart the machine. A particular disadvantage of this is that the position of the cam pole reverser has first to be determined and an extra switching operation needs to be completed before the machine can be set in motion.

Kneading and mixing machines are known in which the work cycle may be pre-programmed so that individual working operations, at different speeds, may be switched on and off automatically-as long as the working operations are not interrupted. If the working operations are interrupted, the steps to be taken to restart the machine depend on whether the machine was stopped whilst in its lower or the higher speed setting.

To pre-programme kneading and mixing machines, moreover, mechanical timers are known which have the significant disadvantage that they continue running when the working cycle is interrupted for example by raising the guard so that the interrupted programme cannot immediately be continued.

Since the elapsed time of the programme is not indicated with such timers, there is a risk that a batch interrupted in this way may not be completed in accordance with the planned requirements.

Electrically driven kneading and mixing machines are known which are fitted with two electric timers, the first timer being designed so that a higher speed can be switched on after a programmed working time has elapsed, operation in this higher speed setting being controlled by the second timer. When starting this type of machine after it has stopped in the lower speed setting, the remaining time of the pre programmed working period is used and once the programmed time for lower speed operation has elapsed, the machine switches automatically to the higher speed setting. When this type of machine is switched off, all the programmed times and the real state are unchanged. But if the machine is switched off, whilst running at its higher speed, it may only be restarted by operating other switches in the lower speed setting.This is done, for example, by resetting the timer for the lower speed back so that after this time has elapsed once again the machine automatically switches to the higher speed setting running for the remaining time at this speed setting. This method changes the pre programmed time for the lower speed operation so that before another batch is done, the working programme has to be reset. Another disadvantage is that an undefined period of working time is added so that the end-product of such a batch may differ from other batches.

With another known type of kneading machine, stoppage in the higher speed requires that, when restarting, the whole of the lower speed operation period be worked again.

An object of the invention is to alleviate or overcome these disadvantages and to provide a kneading and mixing machine which may be restarted, after stopping in a higher speed setting, takes place automatically with a brief initial phase, of preset duration, in the lower speed setting without the pre-programmed settings of the timing system needing to be changed. A further object of the invention is to provide a timing system which enables the use of a kneading and mixing machine in an integrated system, in a large installation, in which control may be effected from a central control panel without requiring major machine conversion.

Another object is to provide a timing system which is readily serviceable.

According to the invention there is provided an electrically powered kneading and mixing machine operable at various speed settings and fitted with a guard which, when raised, switches off the machine, the machine being fitted with a timing system for programming the working times at the different speed settings where in for each speed level that can be set a electronic timing system has a digital real-time and nominal-time display with a working memory and a control unit which is directable from a central input keyboard provided with an input memory.

The use of an electronic timing system makes it possible to use a modular system in which the modules are interlinked via a plug-in system known per se. This sort of system simpler to service as only a defective module need to be replaced should it fail. The use of an electronic timing system also makes it possible to use the treading and mixing machine as an integrated working unit of a centrally controlled large installation when either the input memory-with its input keyboard-isbridged so that the input and operation of the working memory and control units may be effected from the central control panel; or when the input memory-with the input keyboard-is removed as a unit and replaced by the input memory and the input keyboard of the central panel.

The control units of the different speed levels are desireably coupled together such that after the time for the lowr speed level has elapsed, the control unit of the next higher speed level can be activated. This measure results in automatic switchover from the lower speed level to the next higher speed level when the pre-programmed time for the lower speed has elapsed. A timing relay may be connected in series with the control unit for the higher speed level when this is actuated directly when the machine is at a standstill such that there is always a brief run-up for a fixed time in the lowest speed setting.This means that the machine may be stopped in the higher speed setting without disadvantage since a timing relay is triggered which ensures that the machine always starts up in its low speed setting and switches up to the higher speed after a brief fixed cycle time. The chosen time for this starting phase is such that no excessive current peaks occur so that the electrical supply system is not placed under exceptional loads and, moreover, the proportion of the running time in the low speed, relative to the total running time of the low speed, is so small a percentage that the product to be processed is unaffected.

The electronic timing system may take the form of a plug-in modular system such that the working memory and the control units for the different speed levels can be directed from a central processor.

An embodiment of the invention will now be explained with reference to the accompanying drawings, in which: Fig. 1 shows a side view of an electrically powered kneading and mixing machine embodying the invention; Fig. 2 diagrammatically illustrates the controls and dispiays located on the top of the machine of figure 1; Fig. 3 illustrates the circuit diagram of the driving motors in the machine of figure 1; Fig. 4 illustrates the curcuit diagram of the control system in the machine of figure 1, and Fig. 5 illustrates the wiring of connecting blocks L1 and L2 shown in the diagrams of figures 3 and 4.

Figure 1 shows a rotatable vat 1 fixed on a mobile transmission or machine casing 2.

Kneading tools 3 are carried by a mixer head 4 located on the transmission or machine casing 2 to extend into vat 1. A guard 5 is mounted to pivot about a pivot axis 6 and is linked mechanically within the casing to a switch. The machines controls are located on the front face 7 of the mixer head and are described in detail with reference to figure 2.

Figure 2 shows the front face 7 of the mixer head 4 and depicts a display and control panel 8.

This panel comprises two groups of elements:- a digital display and a group of keys and switches.

Numeral 9 denotes an input keyboard with the digits 0-9 with the aid of which a programme may automatically be stored in a memory. A key 10 serves to set a programme time I and a key 11 to set a programme time 11. By pressing the key 12 automatic operation is preset. The unit may be switched to manual operation with key 1 3. The.

values stored in the memory may be erased by pressing a reset key 14. The transfer of the values keyed in to the appropriate display and to the associated working memory is effected by pressing a transfer key 1 5.

Key 1 6 is operable to set the vat of the kneading and mixing machine in motion brieflyat its slowest speed setting-while the key is depressed-independently of the set programme.

Key 1 6 is shown by at B3 in figure 4B.

A stop key 17 may be used to bring the unit to a standstill independently of the programme. The stop key 17 corresponds to key B0 in figure 4A.

The machine is switched on with the aid of start key 1 8 and the kneading tool then runs at speed level I. With the aid of a key 19, the kneading tool can be brought up to speed level ll irrespective of the set programm.

The numerical digital display comprises the REAL time display 20 for operation at speed level I whilst display 21 this reproduces the NOMINAL time for the same speed level operation. Numeral 22 denotes a light-emitting diode L.E.D. the illumination of which indicates to a user that the kneading and mixing machine is working in the first speed level I. An L.E.D. 23 serves similarly to indicate operation at speed level II. The NOMINAL time display for speed level II operation is denoted by 24 whereas figures 25 denotes the REAL time for speed level II operation.

The circuit diagrams shown in figures 3, 4 and 5 are marked in accordance with DIN requirements so these will be understandable to the expert without further explanation.

Figure 3 shows the curcuit diagrams for the vat drive and the drive for the helical kneading tool and their connection to phases R, S2T. Figure 3a shows the vat drive with a 3-phase motor. 1e1-3 denotes fuses generally used and L1 a connector block for a reversing switch whose contacts 712 are shown in detail in figure 5a. Indicia 1 c1 and 1 c2 denote the corresponding motor contactors.

Figure 3b shows the curcuit for the kneadingtools drive in which it can be seen that the motor M can be run at two different speeds. Connection is to phases R, S and T via fuses 2e1 -3. Indicia 2c1, 2c2 and 2c3 denote corresponding motor contactors.

Figures 4c and 4c depict the circuitry linked the individual operating controls. Here the curcuit lies between phase T and Mp and has a fuse e5 and thermal time-lag trips 1 e4, 1 e5, 2e4 and 2e5 connected in series. Contact points L2.1 to L2.17 are shown in detail in figure 5b.

B0 denotes the main switch already mentioned in connection with the description of figure 2 and item 1 7. Switching from manual to automatic operation is effected with switch B5 whose breaker 1, 2 is mechanically connected to breaker 3, 4 (See figure 4a and figure 4b). Switch B4 is linked to the guard and serves as a curcuit breaker. Switch B2 corresponds to the pushbutton 19 in figure 2 and serves to switch in the second speed level II. The timing element rl is a thyristor and delays switch-on by approx. 100,u sec. as an aid to the contactors used to obtain reciprocal interlocking. This measure serves to improve the switchover operation and prevents the contacts sticking. Reference d netotes relays among which relay d5 has particuiar significance.

Relay d5 is an adjustable timing relay which can be set to give a delay of up to 10 secs.

If the kneading tool is switched off in speed level II and is to be restarted in this speed setting afterwards, timing relay d5 becomes effective in that it lets the kneading tool start up in speed level I before switching automatically to speed level II after a preset time (3 secs for example).

This prevents overloading of the electrical mains and of the mechanical components including the tools.

The timing circuitry is activated through contacts L2.1 5, L2.16 and L2.17 as shown in figure 4b. At the same time reference should also be made to figure 5b in which the digital timing system is shown with preselector and erasure keys. This consists of an integrated semiconductor curcuit.

The mains power to the timing system is supplied through contacts L2.13 and L2.14.

The present invention results in a fully automatic kneading-time control system in which both the mixing time and the time for kneading alone are freely selectable independently of one another by appropriate pre-programming using tha keyboard 9 and transfer of the set programme by means of key 1 5 to the corresponding memories. Automatic switchover from one operation to the next is achieved so that through this the entire process is automated in a simple manner. Use of a digital timing system with preselector and erasure keys also gives the possibility, noted at the start, of controlling the kneading the mixing machine centrally from a central panel in a large installation.

Claims

1. An electrically powered kneading and mixing machine operable at various speed settings and fitted with a guard which, when raised, switches off the machine, the machine being fitted with a timing system for programming the working times at the different speed settings where in for each speed level that can be set a electronic timing system has a digital real-time and nominal-time display with a working memory and a control unit which is directable from a central input keyboard provided with an input memory.

2. A machine as claimed in claim 1, wherein control units for different speed level settings are coupled such that after the time for the lower speed setting operation has elapsed the control unit for the next higher speed level is actuable.

3. A machine as claimed in Claim 1 or Claim 2, wherein a timing relay is connected in series with the control unit controlling a higher speed setting, and when this unit is actuated whilst the machine is at a standstill said relay causes the machine to run a fixed time in the lowest speed setting.

4. A machine as claimed in any one of Claims 1, 2 and 3, wherein the electronic timing system comprises a system of plug-in modules enabling the working memories and the control units for the various speed settings to be directed from a central processor.

5. An electrically powered kneading and mixing machine substantially a herein described with reference to the accompanying drawings.