Vibration systems are conventionally used in manufacturing to correctly orientate and deliver small items such as plastic covers to assembly lines. Such systems typically include a vibratory bowl, the vibration of which is controlled by a controller.

Conventional systems have a number of associated problems. Firstly, the controllers of the system are typically on/off switches which do not allow for the system to be fine-tuned for specific applications.

Second, the adjustment of the vibration parameters of the vibratory system is typically achieved by manual adjustment of the vibratory blocks themselves. These blocks are typically located underneath the vibratory bowl or the like and thus are often difficult to access, making fine adjustments a time consuming and difficult task.

According to a first aspect of the present invention, there is provided vibratory apparatus comprising a

vibration means, a support for the vibration means, and at least one spring, characterised in that said spring comprises a composite material.

The vibratory apparatus typically includes at least two springs. The spring is typically a leaf spring, and optionally a flat, leaf spring. The composite material typically comprises a plurality of glass filaments.

Preferably, 85-90% of the filaments are orientated in the bending or primary direction, and 10-15% of the filaments are orientated perpendicular to the primary direction.

The support typically comprises a pair of end plates, the spring being coupled between the end plates.

In certain embodiments, at least one spring is attached at an upper edge of each end plate, and at least one spring is attached at a lower edge of each end plate.

The vibration means typically comprises an electromagnet. The electromagnet typically comprises an armature and a coil.

According to a second aspect of the present invention, there is provided a controller for a vibration system, the controller having an adjustment function for varying one or more of the vibration parameters of the vibration system.

The adjustment function typically allows the amplitude of the vibration of the system to be controlled. This allows a user to accurately set and control the vibration system. Alternatively, or additionally, the adjustment function allows the frequency of the

vibration of the system to be controlled.

The adjustment function preferably allows step-wise increase and/or decrease of the vibration parameters.

The increase and/or decrease in the vibration parameters is typically small values. This allows the vibration system to be finely tuned for a specific application.

The adjustment function typically includes a pulse means for generating electrical digital pulses. The pulse means typically includes an increment button for increasing and/or decreasing the amplitude. The increment button typically comprises a push button switch. The increment button typically generates an electrical digital pulse for each activation of the button.

The pulse means typically further includes an up/down button for selecting whether the amplitude is increased or decreased. The up/down button typically comprises a push button switch. The up/down button typically generates an electrical digital pulse for each activation of the button.

The controller typically controllably converts the electrical digital pulse signals into either a step- wise increasing or decreasing DC voltage level.

The controller is typically coupled to at least one vibratory block, and the controller increases or decreases the amplitude of vibration thereof in response to the respective step-wise increasing or decreasing DC voltage level generated by the controller.

Preferably, the adjustment function includes a feedback system. This allows for automatic adjustment of the vibration parameters to maintain a constant output.

The feedback system typically includes a transducer, the transducer being coupled to the vibration system to measure the amplitude and/or frequency of vibration.

The transducer is preferably a solid state transducer.

This reduces the possibility of failure as there are no moving parts, thus increasing the lifecycle and reliability of the controller.

The controller typically includes a save function to save the vibration parameters. The controller typically includes a save button for actuating the save function. Thus, when the system is powered down (ie switched off) the current parameters are stored for subsequent retrieval when the system is power up (ie switched on).

Optionally, the controller includes a display for displaying the vibration parameters. The display is typically a digital display. This allows for more accurate readings and aids the user in setting up the vibration system.

Optionally, the controller further includes indicia for indicating the status of the controller.

Optionally, a remote controller is coupled to the controller to remotely control the functions of the controller. The remote controller is typically provided with an increment button, an up/down button and a save button. The remote controller optionally includes a display for displaying the vibration parameters. Optionally, the remote controller includes indicia for indicating the current status of

the controller. The remote controller is typically coupled to the controller via at least one opto- isolator.

The controller typically includes fault detection means for determining whether a mechanical resonance frequency of the vibratory block has decreased below a predetermined value.

The resonance frequency of the vibratory block is preferably slightly above the AC line signal frequency powering the vibratory system. The fault detection means typically includes a comparator for comparing the frequency of the vibratory block with the frequency of the AC line signal. The resonance frequency of the vibratory block is typically approximately one to two cycles per second above that of the AC line signal.

The controller optionally includes comparison means coupled to the controller and to be coupled to a vibratory feeder for comparing the rate of article movement along the vibratory feeder relative to the rate of article discharge off of the vibratory feeder for adjusting the amplitude of the vibratory block to match the rate of article movement to that of article discharge. The comparison means typically includes a first photocell for detecting article feed rate along the vibratory feeder, and a second photocell for detecting the article consumption or rate of article discharge off of the vibratory feeder.

The controller typically includes a digital potentiometer.

Embodiments of the present invention shall now be described, by way of example only, with reference to

the accompanying drawings in which: Fig. 1 is a schematic circuit diagram of a logic board for use with the controller of the first aspect of the present invention; Fig. 2 is a schematic circuit diagram of a power board for use with the controller of Fig. 1; Fig. 3 is a front view of a housing for the controller of Figs 1 and 2; Fig. 4 is a plurality of views of the housing of Fig. 3; Fig. 5 is an exploded view of a vibratory block according to the second aspect of the present invention; and Fig. 6 is a plurality of views of the vibratory block of Fig. 5.

Referring to the drawings, Fig. 1 shows a schematic circuit diagram of a logic board which forms part of the controller of the first aspect of the present invention. The logic board includes circuitry for implementing the various functions of the controller.

Fig. 2 shows a schematic circuit diagram of a power board which forms part of the controller of the first aspect of the present invention. The power board includes circuitry for selecting between various input voltages (ie for selecting either 115 and 230 volts alternating current (AC)).

Referring to Fig. 1, a feature of the logic board is a digitally controlled potentiometer 10, which also functions as an erasable-programmable-read-only-memory (EPROM). To control the vibrating system (of which the logic and power boards illustrated in Figs 1 and 2 form part), the amplitude of a sine wave applied through a silicon controlled rectifier (SCR) 12 (Fig. 2) to a vibrating block (not shown) may be varied. This change

in amplitude in the sine wave results in an increase in the amplitude of vibrations at the vibratory block.

A first push button switch 16 (increment) allows the amplitude of the sine wave to be increased, typically by transmitting a digital pulse to the potentiometer 10 each time the first push button 16 is depressed. When the first push button switch 16 is depressed, pin 1 of the digitally controlled potentiometer goes low, causing the output of an operational amplifier 18 to increase. This increase in output voltage at the operational amplifier 18 increases the current through a transistor 20, the output of which is coupled to the gate of the SCR 12, such that the SCR 12 is triggered earlier on in the firing cycle. The increase in current to the gate of the SCR 12 causes an increase in the voltage across the vibratory block (not shown) which is connected to the terminals H1 and H2 on a junction 22 (Fig. 2), thus causing the amplitude of the vibrations at the vibratory block to increase.

Repeated depression of the first push button 16 causes the amplitude of the vibration to be increased by an incremental amount for each depression of the first push button switch 16.

A second push button switch 24 (up/down) is used to control the function of the first push button switch 16, typically by sending a second digital pulse to the potentiometer 10. If the first push button switch 16 is depressed alone, then the vibrations at the vibratory block will incrementally increase for each depression of the first push button switch 16 as described above. If the second push button switch 24 is pushed and held depressed, then the amplitude of the vibrations at the vibratory block will decrease by an decremental amount for each depression of the first

push button switch 16 whilst the second pushed button switch 24 is held depressed. It should be noted that the second push button 24 may be held down constantly, whilst the first push button is depressed a number of discrete times to facilitate fine tuning of the amplitude of the vibrations.

When the first and second push button switches 16,24 are depressed simultaneously, or when the second push button switch 24 is held depressed and the first push button switch 16 depressed once or repeatedly, the inputs to pins 1 and 3 of the digitally controlled potentiometer go low. Consequently, the output voltage at pin 5 of the potentiometer reduces, causing the current through the transistor 20 to decrease. This reduces the voltage at the gate of the SCR 12, thus reducing the potential across the vibratory block and the amplitude of the vibrations.

A single depress of the first push button switch 16 typically changes the current to the gate of the SCR 12 by, for example, between 0.125 and 0.2 Amps. This change in current results in an increase of amplitude of about twenty thousandths of an inch (approximately 0.58mm). A similar reduction in current and amplitude result when the first and second push button switches 16,24 are depressed simultaneously.

To avoid having to reset the amplitude of the vibrations after power to the controller is switched off, a third push button switch 26 may be used to store the current settings of the digitally controlled potentiometer 10 in the EPROM which forms a part of the potentiometer 10. Thus, when the controller is switched off and then switched back on, it will automatically re-initialise to the vibration amplitude

level previously set before the third push button 26 was depressed.

Optionally, a display screen such as a liquid crystal display (LCD) 28 may be used to monitor the amplitude level. Thus, when an increase or decrease in amplitude is desired, the first and second push button switches 16,24 are depressed accordingly and the amplitude of the vibrations is displayed on the LCD 28. This allows the level of amplitude to be monitored and set more accurately. Conventional controllers use an analogue scale to set the amplitude which is less accurate and relies on a user correctly interpreting the value from an analogue display.

Optionally, a solid state accelerometer or transducer (not shown) may be coupled to the vibrating block. The transducer is used as part of a feedback loop for automatic control of the vibratory system, and typically produces an AC sine wave which is proportional to the vibrations at the vibratory block.

The AC peak voltage is converted to a direct current (DC) voltage by a convertor circuit, generally designated 44 in Fig. 1. The DC voltage is used as a reference voltage for servo control, the DC voltage being applied to the operational amplifier 18 which is configured in comparator mode. Thus, the controller will automatically keep the amplitude of vibration substantially constant.

Conventional systems use a photoelectric interrupter transducer (not shown) which typically comprise a light emitting diode (LED) and a phototransistor which face one another across a slot. A pin or the like is mounted to the vibratory block wherein movement of the block moves the pin in and out of the slot, thus

interrupting the beam between the LED and the phototransistor. As the vibrator oscillates, the phototransistor is alternatively light and dark which provides an amplitude dependent signal to the controller.

These mechanical transducers are not as reliable as solid state transducers as they have moving parts and are prone to failure. In addition, the amplitude dependent signal from the mechanical transducers is not always accurate.

In order to increase the accuracy and lifetime of the transducer, a solid state transducer (not shown) may be used. The transducer is coupled to a junction 46 on the power board (Fig. 2). Unlike the conventional filtered transducer signal which is often slow, or the use of sample and hold circuits with fixed duration and trigger times, the solid state transducers are more tolerant of electrical noise and phase shift. Thus, more reliable automatic control of the system can be achieved in harsh industrial environments.

In addition, the transducer allows the mechanical condition of the vibratory block to be monitored, even from a remote location, using, for example, an intelligent controller such as a programmable logic controller (PLC). One indication of impending failure of a vibratory block is a decrease in the mechanical resonant frequency. It has been found that a vibratory block works at peak performance when its resonance frequency is tuned slightly above the frequency of the AC line voltage powering the block. For example, an optimal frequency of resonance is about 61.5 Hz to about 62.0 Hz for an AC line frequency of 60 Hz. As the vibratory block begins to wear, the frequency of

vibration begins to approach the line frequency and then becomes lower than the line frequency.

The controller can be used to determine when the frequency of vibration falls below the AC line voltage frequency by indicating a fault condition by means of fault circuitry, generally designated by numeral 34.

The fault circuitry 34 compares the AC line signal and the sinusoidal signal derived from the transducer or accelerometer coupled to the vibratory block. The AC line signal is modified for phase comparison with the transducer signal by being sent through a zero-crossing detector, generally designated 35 in Fig. 1. The modified line signal is then delayed 90° at a delay stage, generally designated 37 in Fig. 1. The modified line signal is then translated into a signal having a slope at a ramp stage, generally designated 39 in Fig.

1. The slope, which is a function of the number of digital pulses generated by the push button switch 16 or a remote controller is compared to a DC level signal from the transducer. The lower the voltage of the signal from the transducer, the earlier in the cycle the SCR 12 will be triggered based on a predetermined setting of the digital potentiometer 10. The phase angle of the signal from the transducer can be compared with the phase angle of the AC line voltage. A transducer lagging phase angle indicates that maintenance of the vibratory block may be required.

To monitor the status of the controller, two light emitting diodes (LEDs) 30,32 are provided. LED 30 is typically a green LED and indicates that the vibratory block is running. LED 32 is typically a red LED and indicates that there is a fault in the system, typically resulting from a lowered frequency of vibration. The fault circuitry 34 includes a timer

circuit which controls the operation of the LEDs 30, 32, causing them to pulse rather than light continuously to conserve power.

Operation of the controller may be controlled remotely by an intelligent controller (not shown) which is coupled to a junction 36 on the power board (Fig. 2).

The intelligent controller may be in the form of a programmable logic controller (PLC) and typically allows a user to increase or decrease the amplitude of the vibrations remotely. The status of the controller may also be displayed on the intelligent controller by using similar LEDs to the LEDs 30,32. Optionally, the amplitude of the vibrations may be displayed on an LCD on the remote controller. The circuitry of the intelligent controller is isolated from the circuitry of the controller using opto-isolators 38,40,42 (Fig.

2). The opto-isolators 38,40,42 isolate the increment and up/down switches on the intelligent controller and also the status LEDs. Note that the intelligent controller may be used without digital to analogue conversion, thus reducing the over-all cost and complexity of the controller. The digital pulses generated by the intelligent controller (eg a PLC) can simulate a more complex and expensive analogue circuitry which would otherwise be required to adjust the amplitude of vibration from a remote location.

Relay outputs on junction 50 (Figs 1 and 2) indicate that the vibratory block is vibrating and can be used to control other equipment, such as line feeders, vibrating lines or the like, and/or may be used to signal the intelligent controller.

Input to the controller is typically single phase line neutral and earth ground. Output from the controller

is typically single phase half wave. A feature of the controller is a transformer circuit generally designated 48 in Fig. 2. The transformer circuit allows the controller to be operated from 115 or 230 volts AC. The input voltage is selected using jumpers.

This provides a more versatile controller.

Figs 3 and 4 show a plurality of views of a typical housing for the controller of the present invention.

Fig. 3 is a front view of the housing, showing the LCD display 28, the status LEDs 30,32 and also the push buttons 16,24 and 26. Fig. 4 is a plurality of views of the external faces of the housing.

Referring now to Figs 5 and 6 there is shown a vibratory block 100 according to a second aspect of the present invention. The vibratory block 100 comprises a pair of heavy end plates 102a, 102b which are coupled together by at least one pair of composite leaf springs 104a, 104b. The springs are separated from the end plates 102a, 102b (and from each other if more than one pair is used) by a pair of spacers 106.

One of the end plates 102a has an encapsulated coil and iron core, generally designated 108, coupled thereto, which forms part of an electromagnet. The opposite end plate 102b has an armature 110 coupled thereto.

The air gap between the encapsulated coil and iron core 108 and the armature 110 is typically adjustable. The springs 104a, 104b and spacers 106a, 106b are mounted to the end plates 102a, 102b using clamp bars 112 and mounting screws 114.

One or more pairs of springs 104a, 104b are used, depending upon the weight of the vibratory equipment which the vibratory block 100 is to drive. The spacers

106a, 106b between the end plates 102a, 102b and the springs 104a, 104b are used to reduce friction and to prevent fretting corrosion at the clamped end.

The composite springs 104a, 104b are preferably manufactured from continuous glass filaments which are orientated in a particular manner. Approximately 85- 90% of the filaments are orientated longitudinally in the bending or primary direction. However, 10-15% of the filaments are positioned just under the surface and are orientated to be approximately perpendicular to the longitudinal filaments. This increases the strength of the spring 104a, 104b in the"cross"direction.

Composite springs 104a, 104b provide a number of advantages. Firstly, the springs 104a, 104b give improved pressure distribution. Secondly, the springs 104a, 104b have a longer lifetime. Thirdly, composite springs 104a, 104b can move further; that is, conventional steel springs can flex approximately one quarter of an inch (approximately 6.25mm), whereas the composite springs 104a, 104b can flex by about 0.32 inches (about 8mm). This amplitude difference is advantageous in vibratory equipment, and gives a wider range of vibration. In addition, composite springs 104a, 104b can store more energy and thus reduces the amount of current required to drive the vibratory system, making the system more efficient.

Thus, there is provided a controller for vibration system which, in certain embodiments, is more versatile and offers many advantages over conventional systems.

The controller in certain embodiments may be used to set the amplitude of vibration, which may then be stored for subsequent retrieval. Other features include the possibility of remote control.

There is also provided an improved vibratory block for use with vibration systems. The vibratory block uses composite springs which provide many advantages over conventional steel springs.

Modifications and improvements may be made to the foregoing without departing from the scope of the present invention.