CA1048606A - Apparatus for automatic adjustment of frequency of mechanical resonators - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Apparatus for the automatic adjustment of the resonant frequency of magnetic mechanical resonators, in which conveyor means are provided to feed a plurality of resonators step by step through a demagnet-ization station and a magnetization station to a final measurement and processing station in which the resonant frequency is monitored whilst material is removed by bombardment with a laser beam, the final output of the conveyor being to a selected ejection stage determined by the tuning accuracy achieved in each case.

Description

10~ 6 The invention relates to apparatus for the automatic adjust- -ment of the actual frequency of mechanical resonators of a magnetic material, which aro provided with pin-like holding elements, the adjustment bringing the resonator frequency to a given theoretical frequency by the removal of resonator material using laser radiation controlled in dependence upon a difference frequency obtained from a comparison of the theoretical and actual frequencies.
On account of their high oscillatory quality and their small space requirement, mechanical resonators enjoy wide-spread use, for example as frequency standards or in mechanical filters. In virtually all cases of -use it is of importance that the resonance frequency of such a mechanical resonator should occur at a predetermined frequency that is set as accurately as possible. As a result of the unavoidable requirement to allow production tolerances in the production of the resonators, generally this requirement is not sufficiently fulfilled, so that it is necessary to adjust the final resonance frequency of such a resonator following its produc~ion. It is known to carry out this process which is known as "adjustment" or "balancing"
by removing resonator material with the aid of a grinding process, or by . sand blasting, or by the use of laser beams. In this connection a process --for the frequency adjustment of mechanical resonators is described in the German Patent Specification No. 1,929,994 of Siemens AG, issued October 21, 1971 in which the setting of the given resonance frequency takes place by a controlled vaporization of resonator material with a laser beam. In the process described in this patent, the resonators are excited to mechanical oscillations which are converted into electric oscillations corresponding to the actual frequency of the resonators, and then amplified. The amplified electric oscillations are subjected to comparison with ' ,. ~

- 2 -, 1~)486~6 a theoretical value, and the vaporization of resonator material by means of a laser beam is controlled by the resultant difference fre-quency. In order to achieve uniformly good results wi~h this process however, it is necessary to use uniformly bias-magnetized resonators, as these are excited via a drive magnet to oscillations whose freque-ncy is to be measured. Therefore it is necessary~ for the resonators, having been pre-adjusted by a grinding process, to be de-magnetized prior to the actual magnetization.
Following the actual adjustment process, the resonators must be checked to establish whether their resonance frequency lies within the given tolerance - frequency range, and if this is not so, , i.e, when a particular resonator is not capable of oscillation as re-quired, that particular resonator must be selectively rejected.
~hus both prior to and following the actual adjustment pro-cess, additional operating sequences are required, with special asso- ~ ~ -ciated devices. This inevitably gives rise to long transport times between the individual operating sequences and conveyance times for the individual devices, and likewise increased outlay in personnel for the operation, and in the conveyance and servicing of these de-~i 20 vices. Because of the different natures of the individual operating sequences, and the associated devices, it is difficult to fully a~o-mate such an adj~stment process.
One object of the present invention is to provide an ap~
; paratus for the frequency adjustment of mechanical resonators, in which all the above-described operating sequences may take place fully automatically in one relatively economical device.
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The resonators which are to be adjusted are automatically conveyed to the consecutive processing stations and can remain in the , : .............................. . .

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10~86(~6 guide rail or the holders of the rotary indexing table whilst thereon during all the processing. This obviates the need for manpower for the conveyance and transportation of the resonators between individual processing devices.
Another advantage consists in the fact that a separate measurement of the resonance frequency, which is normally required for con-ventional sorting of the resonators ~ollowing the adjustment process, is rendered unnecessary as the respective measurement which concludes the sand blasting adjustment for any resonator is stored and used to selectively control the individual ejection stations for routing that resonator.
The combination of the various operating sequences required for the adjustment of the resonators within one single device produces the particularly advantageous possibility of a simple, central control of these operating sequences.
Thus, in accordance with the present invention, there is provided apparatus for the automatic adjustment of the actual frequency of ,~
,;` mechanical resonators of magnetic material and provided with pin-like holding lements, in which laser means are provided for the removal of resonator , material by controlled radiation to adjust the frequency to a given theoretical value in dependence upon a difference frequency obtained by comparison of , 20 the theoretical frequency and a value representing the actual frequency as determined by a measuring device, means being provided to convey the resonators to a guide rail, along which are positioned a demagnetization station a stop means pivotable into the guide rail at a magnetization station an end stop being provided at the termination of the guide rail, where the pin-like ` holding elements of each incoming resonator are gripped by an oppositely located, closing holder which conveys that resonator to a laser adjustment device where the frequency is measured by said means and material removed as necessary, the final measurement of the resonance frequency at the termination of the laser adjustment process being stored and compared with a given toler-, 30 ance frequency range, and used to selectively control ejection of that reson-;- ator from a selected one of a plurality of ejection station in accordance ., ~486(~6 with the measured resonance frequency for that resonator.
The invention will now be described with reference to the drawings, in which:-Figure 1 is a schematic side view of one exemplary embodimentof apparatus constructed in accordance with the invention;
Figure 2 is a plan view of the apparatus shown in Figure l;
Figure 3 shows details of a separating station in the apparatus;
. Figure 3a is a perspective view of the separating station in . detail;
Figure 4 is a section through a magnetization station in the apparatus;
. Figure 5 is a plan view of a holder in the apparatus;
Figure 5a is a side view of the holder shown in Figure 5; -:

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- 4a -''' 11~)486~6 Figure 5b is a section through the holder'shown in Figure 5; and , Figure 6 schematically illustrates an ejection station operated bv means of a lifting magnet in the apparatus.
, The adjusting device shown in Figure 1 consists of a plurality '' 5 of assemblies which are mounted on a common base plate 1. Arranged ,, in the centre, for the transport of resonators to an actual adjustm-ent station 3 is a pneumatic rotary indexing turn-table 2 of the type ' commercially available under the reference ST-270 from the Vesto co-mpany, this being provided with twelve indexing positions. For the support of the resonators, the rotary indexing table possesses a nu-' mber of holders 4, which in number conform to the number of indexing ,' positions, and which are arranged concentrically to its axis of rot-ation and at equal intervals. The resonators are conveyed to the ro-~; tary indexing table by means of a feed device which is secured to the base plate and which contains a vibrator device 5 and a guide rail 6 which is connected to the output of the vibrator device to receive and feed the resonators along. In the represented exemplary embodi-;~ ment, the vibrator device 5 is a conveying and sorting device comme-rcially available under the name "Sortimat", which is set up for the resonators which are to be adjusted, and comprises a vibrator base with an electromagnetic vibrator, a sorting trough and a separatel~
'' arranged indexing device, via which the feed speed of the resonators can be controlled.

The resonators, emerging in a row from the vibrator device 5, Co~ ; ~ 25 are eeR~erte~ to the guide rail 6, which is initially horizontal and then slants downwards, and on passing along said guide rail they fi-rst pass through a demagnetization station 7, which is in the form of a coil, and then pass through two light opto-electric detector moni-, . . .

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10486(~6 : toring points 8 which serve to monitor the continuous transport of the resonators and control the switching on and off of the vibrator .~ device. The resonators subsequently enter a vertical part of the gu-ide rail, to reach a separating station 9 in which they are held sta-S tionary and magnetized by a magnetization means 10. The magnetized resonators are then fed from the separating station 9 in accordance ` with a pulse train produced in a control device and pass individually .. from the separating station to a lifting station 12 which is arranged at the end of the guide rail and i5 provided with an end stop 11. An incoming magnetized resonator 13 is shown in the station 12, with its end against the end stop 11, to rest with its pin-like holding elem-ents between the open clamping jaws of an oppositely located holder - 4 on the pneumatic rotary indexing turn-table 2, and its pin-like ho-lding elements are subsequently gripped by the holder 4. The rotary 15 indexing turn-table 2 then conveys the resonator, arranged in the ho-lder, to a laser adjusting device which is combin~d with a measuring device and a first ejection station. At this point, the resonance frequency of the resonator 14 is alternately measured and then adju-sted by working its end face by radiation from the laser to remove ~0 material until the actual resonant frequency is within two cycles ~jCQ/

: ~ per second of the theorcc-t~-ca~ frequency. In order that the resona-; nce frequency can be measured, the resonator 14 is set in oscillation by means of a coil 15, and its inherent frequency is determined via . a microphone 16. The measurement result is compared with a given to-lerance-frequency range by an electronic control device and if the : resonator is not capable of oscillation it is deposited, via a chute, into a container 17 forming part of the first ejection station, or if the measured frequency is two high it is ejected following further , .' ' ' ~

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1~4~06 steps of the rotary indexinq turn-table at an ejection station prov-ided for resonators which have become resonant abPve the tolerance :: range upper limit, whilst if it is within tolerance it is ejected at ; another ejection station, provided for correctly adjusted resonators.
For reasons of clarity, the horizontal and oblique parts of the guide rail 6, which run tangentially to the rotary indexing table as . shown in Figure 2, is shown in Figure 1 as extending in radial dire-ction relative to indexing turn-table. As mentioned above, in the present exemplary embodiment, the laser adjusting device and the fir-rst ejection station for non-oscillatory resonators are combined to ; form one station, together with a measuring device.
Figure 2 is a plan view of the apparatus shown in Figure 1, in which the tangential course of the guide rail 6, and the arrangement of the holders 4 on the indexing turn-table 2-can be clearly seen, 15 together with details of a lifting magnet 18 which is secured to the guide rail construction and serves to close the particular holder 4 arranged opposite the lifting station, a microphone 16 and coil 15 which serve to measure the resonance frequency of that resonator 14 20 arranged in the adjusting station, two ejection station containers 17 with ~ection means operated by associated lifting magnets l9, and provided respectively for non-oscillatory and mal-adjusted ~ resonators, and also a further ejection station which is operated by , a rotatable roller 20 and which serves to feed resonators that are I,.. .
~5 adjusted within theresonance frequency range into an associated con-tainer 17. The liftirgmagnets 21 and 22 which are secured to a sup-por~ for the guide rail 6 are assigned to the magnetization station . 10 and the separating station 9.
Figure 3 illustrates details of the end zone of the guide rail ,~ .
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-10486~6 6 with its separating station 9, magnetization station 10, lifting station 12 and end stop means 11. The separating station 9 consists of a rod-shaped upper lever 23 and a rod-shaped lower lever 24 arran-ged in parallel to the former, both of which are mounted to be pivot-able about a common axis of rotation 25, running parallel to the cen-tral axis of the guide rail 6, in a fixing rail 26, the two levers being rigidly connected together via braced link 27. That end of the lower lever 24 which lies remote from the axis of ro~ation 25 is ta-pered and provided as stop means 24' to engage any resonators such as the resonator 30 which is shown in the position required for it to be magnetized. The upper lever 23 has its end remote from the axis of rotation 25 connected to an extension in the form of a leaf spring ~; 23'. The guide tail 6 possesses a slot-like recess in each case at . . .
the level of that end of the lower lever 24 which forms the stop me-ans 24', and at the level of the leaf spring 23' thus facilitating , the engagement of the stop means 24' and of the leaf spring 23' into the conveyor area of the guide rail. By virtue of the deflection of an armature 28 belonging to a lifting magnet 22 (Figure 5) and acting ' on the centre of the braced link 27, both levers can be commonly mo-ved against the force of a helical tension spring 29 acting on the braced link 27.
When the armature 28 is in the rest position, the stop means 24' i is pivoted inside the conveyor space of the guide rail, which bears ~:, ' the resonators, and the leaf spring is at the same time located out-side the conveyor space. In this position the resonator 30, abutting against the stop means 24' can be magnetized by the magnetization st-ation 10. Then, with a continuous movement of the armature 28 again-, st the tension of the helical spring 29, a position is passed through -~ .

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~6)486~6 in which the stop means 24' is still pivoted inside the conveyor spa-ce, but the resonator which follows the magnetized resonator 30 is g-ripped by the leaf spring 23' on its rear, which lies opposite its h-; olding elements, and is thus pressed against the guide rail. When the armature 28 then moves on into its operative position, the stopmeans 24' is pivoted out of the conveyor space, whilst the clamped r-esonator is still held by the leaf spring 23'. The magnetized reson-ator 30 then falls against the end stop 11 of the lifting station 12.
With the following, reverse movement of the armature 28 back to its rest position, the stop means 24' is pivoted into the conveyor space of the guide rail and the clamping of the next resonator is terminat-ed, so that said resonator can move to the stop means 24' and a furt-- her resonator come to the level of the leaf spring.
Figure 3a gives a perspective view of the mobile elements of the separating station, in which, for reasons of clarity, both the guide rail 6 and the securing rail-26 have been omitted, but the resonators contained within the guide rail have been represented.
Figure 4 is a section through the magnetization station 10, whi-i ch possesses a fixed contact 31 connected to an earth point, and a mobile contact 33, which is insulated by means of insultators 32 andis operated via the armature of a lif~ing magnet 21. The resonator 30, here shown is that one resting against the stop means 24' (Figure

3) in the separating station 9, and is magnetized by means of a surge of current flowing between the fixed contact 31 and the mobile cont-i~. .
act 33 from a source (not shown). Following the magnetization, the mobile contact 33 is removed from the resonator via the armature of the lifting magnet 21. The magnetized resonator is now able to move when the pulse train from the control device provides a control pulse ~9_ ':. - ' .
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104~6 and is conveyed through the separating station to the lifting station 12.
Figures 5 and 5a illustrate one of the holders 4 mounted on the periphery of the rotary indexing table 2, in a plan view and a side view respectively. As in each of these illustratio~sonly a part of the holders are visible, Figures 5 and 5a will be commonly described in the following.
The holder 4 contains a rod-shaped first clamping jaw 34 which is rigidly connected to the indexing turn-table and is combined with two fixing plates secured to its lateral faces to form a unit 34' of U-shaped cross-section, and also possesses a second rod-shaped clam-ping jaw 35 whi~h lies in parallel opposite the first clamping jaw, and which is mounted in the fixing plates to be pivotable about a perpendicular axis of rotation 36. Both of the clamping jaws 34 and 35 are a~igned radially to the indexing turn-table, and are provided at their ends facing the processing stations wi~h-opposed vertical clamping faces 37 whilst their other ends are connected to one ano-ther via a helical pressure spring 46 (Figure 5b).
In the present exemplary embodiment, the second clamping jaw 35 is divided by a horizontal sectional plane into two halves 35', '~ which on their sides facing away from the first clamping jaws are rigidly connected to one another via a 90 elbow 38, at a distance which ensures that in each case one of the pin-like holding elements of the resonator 39 is clamped by in each case one half of the sec-ond clamping jaw. Each holding element is thus individually clamp-i ed by a respective one half, and thus the clamping reliability is considerably improved. The 90 elbow 38, whose free flank extends ' upwards is used to cause the closed clamping jaw to be opened, in - ~
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1~;J48~;~6 that its free flank is deflected in the direction of the arrow 40. me holder also contains a prismatic elbow 41 which at its one end is-mounted to be pivotable between the fixing plates, and which is mechanically biased by a spiral spring 42 towards those ends of the halves of the second clamping jaw 351 which face away from the processing stations, and serves to lock the open clamping jaws in position. This locking is ensured in that the ends of the halves of the second clamping jaw 35' are accommodated in a matching recess 47 (Figure 5b) in the locking component 41, when the holder is open. At its end which lies opposite the axis of rotation, the prismatic locking component 10 41 is extended vertically upwards by an arm 43 which branches off at right ; angles. A deflection of this arm 43 in the direction of arrow 44 causes the locking of the clamping jaws in the open position to be discontinued~ and the clamping jaws then close as a result of the pressure of the hellcal spring 46 located between the clamping jaws. me deflection is carried out in the lifting station 12 by means of the armature of the lifting magnet 18 (Figure 2) which latter is secured to the guide rail support.
Figure 5b shows a sub-longitudinal section, in the horizontal direction, through an open holder, revealing the helical spring 46, inserted in a bore 45 in the first clamping jaw 34 and pressed against the second 20 clamping jaw. mose ends of the open, second clamping jaw halves 35' which are remote from the clamping surfaces 37, are here accommodated in the form fitting recess 47 in the locking component 41, which is biased by the spiral spring 42 towards these ends.
Figure 6 schematically illustrates details of that ejection station provided for resonators which have been adjusted to a frequency out- ~
; side the given tolerance frequency range and are therefore to be rejected. ;
It contains a lifting magnet 19 (see also Figure 2), which is secured to the base plate, and has an armature 19' that is aligned such that its longitudinal axis extends radially relative to the indexing turn-table 2. The lifting ; -11- -.

1~;1486Q6 magnet 19 is secured at a sufficient height above the indexing turn-table to ensure that when the table rotates, ~he holders move passed underneath its armature 19'. m e holder is opened by deflecting the rectangularly upwards-extended part of the free flank of the 90 elbow 38 in the direction of arrow 40 with the aid of the armature 19' of the lifting magnet.
In the last ejection station, which is provided to receive correct- -ly adjusted resonators, the free flank of the 90 elbow 38 is deflected by a roller 20 (Figure 2) which is rotatable about a vertical axis and the holder is thus opened. On the further rotation of the rotary indexing table, the holder remains open until it is again turned to the station lying opposite the lifting station 12.

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Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Apparatus for the automatic adjustment of the actual frequency of mechanical resonators of magnetic material and provided with pin-like holding elements, in which laser means are provided for the removal of resonator material by controlled radiation to adjust the frequency to a given theore-tical value in dependence upon a difference frequency obtained by comparison of the theoretical frequency and a value representing the actual frequency as determined by a measuring device, means being provided to convey the resonators to a guide rail, along which are positioned a demagnetization sta-tion a stop means pivotable into the guide rail at a magnetization station an end stop being provided at the termination of the guide rail, where the pinlike holding elements of each incoming resonator are gripped by an op-positely located, closing holder which conveys that resonator to a laser ad-justment device where the frequency is measured by said means and material removed as necessary, the final measurement of the resonance frequency at the termination of the laser adjustment process being stored and compared with a given tolerance frequency range, and used to selectively control ejection of that resonator from a selected one of a plurality of ejection station in accordance with the measured resonance frequency for that resonator.

2. Apparatus as claimed in Claim 1 in which a rotary indexing turn-table is arranged on said base plate to support and move said holders which are arranged concentrically to the axis of rotation of said table and spaced at equal intervals about its periphery, a feed device frequency processing station and ejection stations being positioned about said table to lie opposite respective holders when the turn-table is stationary at any indexed position, said means for conveying resonators to said guide rail which is connected to the output of a vibrator device comprises at least one light sensitive monitoring position to detect the passage of resonators, and said guide rail being sharply curved or vertical adjacent its end remote from the vibrator device, where said end stop is provided, any resonator abutting against the end stop having its pin-like holding elements between the open clamping jaws of an oppositely located holder.

3. Apparatus as claimed in Claim 2, in which said magnetization sta-tion incorporates a separating station with a rod-shaped upper lever and lower lever aligned in parallel, both levers being rotatable about a common axis of rotation running parallel to the central axis of the guide rail and being rigidly connected to one another via a braced link so that end of the lower lever which lies opposite the axis of rotation serves as stop means the upper lever being provided with a leaf spring, both levers being commonly rotated as a result of the deflection of a lifting magnet armature acting upon the braced link against the force of a helical tension spring both levers occupying a position during the rest position of the armature in which the armature is located within the conveyor space of the guide rail bearing the resonators, whereas said leaf spring lies outside of said space so that a first resonator is held stationary against the stop means, and at the follow-ing position of the levers the stop means and the leap spring assume a posi-tion in which the stop means still lies within the conveyor space, and a second resonator which follows the first resonator is clamped by the leaf spring in the guide rail and that in the position of the levers which occurs when the armature is in the operative position the second resonator remains clamped whereas the stop means is pivoted out of the conveyor space.

4. Apparatus as claimed in Claim 3, in which said magnetization sta-tion serves to magnetize a resonator abutting against said stop means using a fixed first contact which is connected to earth, and an insulated second contact which is movably operated by the armature of a second lifting magnet and that the magnetization is effected by a controlled passage of current be-tween the contact points to the resonator whilst clamped between said con-tacts.

5. Apparatus as claimed in Claim 3, in which each said holder possesses a rod-shaped first clamping jaw which is rigidly connected to said indexing turn-table and radially aligned thereto, together with an oppositely located, rod-shaped second clamping jaw rotatable about a vertical axis of rotation, both clamping jaws being provided at their ends facing the processing stations with vertical clamping surfaces which lie opposite one another, and at their remote ends connected to one another via a helical pressure spring, the first clamping jaw being provided with two horizontal fixing plates which are se-cured to its ends and extend at least to the axis of rotation, which axis of rotation is in the form of a pin conducted through the second clamping jaw and mounted in the fixing plates, and a 90°elbow being connected by one flank rigidly to that side of the second clamping jaw facing away from the first clamping jaw, the clamping jaw being held opened by virtue of the de-flection of the rectangularly upwards-extended free flank of the 90° elbow to bring a prismatic locking component into a position which locks the open clamping joint which at its one end is mounted to be rotatable between the fixing plates and at its other end is provided with an arm branching off at right angles in the upwards direction, the locking component being mechanical-ly biased by a spiral spring towards that end of the second clamping jaw re-mote from the processing stations, such that when the clamping jaws are held open this end side is accommodated in a matching recess in the locking com-ponent.

6. Apparatus as claimed in Claim 5, in which said first clamping jaw is combined with fixing plates to form a unit of U-shaped cross-section, said second clamping jaw being divided in a horizontal plane into two halves rigidly connected together via said 90° elbow at a distance whereby in each case one holding element is clamped by one half of the second clamping jaw.

7. Apparatus as claimed in any one of Claims 2, 5 and 6, in which at least one of said ejection station possesses a lifting magnet whose armature has its longitudinal axis aligned radially to said indexing turn-table, and serves to open the associated one of said holders by deflection of the free flank of the 90° elbow.

8. Apparatus as claimed in any one of the Claims 2, 5 or 6, in which the last ejection station, considered in the direction of rotation of the indexing turn-table, includes a roller which is rotatable about a vertical axis, and which serves to open the associated holder by deflection of the free flank of said 90° elbow.