for the purposes of promoting an understanding of the principles of the invention , reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same . it will nevertheless be understood that no limitation of the scope of the invention is thereby intended , such alterations and further modifications in the illustrated device , and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates . referring to fig1 there is illustrated an autoclave cassette 20 for dental instruments and appliances . the cassette 20 includes a pair of drawn , generally rectangular trays 21 and 22 which are in effect tray halves and are identical in size , shape and hole patterns . the only difference between the two tray halves relates to the two - piece latch 23 where the slide portion 24 is riveted to the front wall of tray 22 and the retainer portion 25 is riveted to the front wall of tray 21 . however , trays 21 and 22 are still machined in an identical fashion such that the slide portion 24 and the retainer portion 25 can be attached to the front wall of either tray , interchangeably . the slide portion 24 has a split bayonet design with a narrow slit extending into an enlarged opening . the retainer portion 25 has a shouldered pin having an enlarged head which is received within and anchored by the slide portion 24 . riveted in place to the base or bottom surface of each tray is a three - sided , part - rectangular instrument retainer frame 28 configured with opposite end walls 29 and 30 each of which are contoured with seven curved recesses 31 . the curved recesses 31 in each end wall are aligned with the opposite wall so as to in effect provide a straight channel which is used to support and retain dental instruments and appliances , see fig2 . retainer 32 which is disposed only in tray 22 serves to hold the dental instruments in both tray halves ( i . e ., in retainer frames 28 ) when the cassette is closed . retainer 32 is received at one end by pivot block 33 and at the opposite end by slotted bracket 34 . retainer 32 will typically be partially covered by a resilient , flexible sleeve ( noted by the broken line 32a ) which serves as a resilient cushion against the dental instruments which are loaded into the two frames 28 . the sleeve is preferably constructed from an extruded silicone material . the resilient member , though typically a sleeve , may alternatively be a flexible , resilient member such as a tube or rod which is wedged into opening 32b to provide the cushioned compression on the dental instruments . in this manner the retainer 32 is designed to securely hold down the dental instruments and appliances which are loaded into frame 28 of tray 22 . by placing tray 21 on a horizontal surface , the instruments in frame 28 of tray 21 will be held in position by gravity . retainer 32 must still clamp the instruments in tray 22 while the tray 22 opens as the cassette lid . when the lid ( tray 22 ) is closed for autoclaving the retainer acts on both sets of dental instruments concurrently . retainer 32 includes a generally planar main body portion which is constructed with two substantially parallel arms 32c and 32d which provide two spaced - apart pressure points on each instrument so as to prevent rocking or tilting of the instruments as might occur with only a single pressure point . examples of the types of dental instruments or appliances which may be retained in frame 28 include dental mirrors and picks . each of these devices is elongate and typically has a length dimension such that it will extend beyond the end walls 29 and 30 of frame 28 . for this reason each frame is inset from the side walls of the corresponding tray leaving clearance spaces 29a and 30a at each end . since the dental devices can be oriented in either direction in the recesses 31 of frame 28 , it may be either the handle portion or the tip portion of each device which extends beyond the frame into the clearance spaces . it is also possible to orient these instruments in an alternating or reverse direction depending on the preferences of the dentist or dental assistant . the area left between the front wall of each frame and the front wall of the corresponding tray half may be used for other dental instruments and appliances which are either too large to fit within the aligned recesses 31 of frame 28 or which may be too small to be received in that they will not extend that distance . for small items a wire screen or mesh container may be used for storage during autoclaving . such container or containers are sized to fit in the clearance area between the front wall of the frame and the front wall of the tray half . however , for larger items and for any small article containers , the clearance depth of both trays would likely be required as contrasted with items retained in the retainer frame 28 . consequently , two frames can be used due to the article height enabling a total of 14 instruments or appliances to be retained in the frames of each individual cassette in addition to whatever larger articles or smaller items may be placed in the front clearance area . pivot block 33 is riveted in place to the front wall 35 of retainer frame 28 in tray 22 . the slotted bracket 34 is riveted in place to the rear wall 36 of tray 22 . as illustrated the rivet which attaches the slotted bracket 34 to the rear wall 36 actually extends through one flange of the hinge such that the center rivet actually secures the slotted bracket and one flange of the hinge and the rear wall 36 of tray 22 all together . in use , one end 37 of retainer 32 is pivotably retained in block 33 and the opposite end 38 of the retainer 32 fits within in slot 39 . block 33 includes a cylindrical bore into which a bearing sleeve 33a is placed and end 37 is axially retained in the sleeve . screw 33b extends over the edge of the sleeve 33a so that the sleeve cannot be withdrawn from the cylindrical bore without first removing the screw 33b . when a dental instrument or appliance is to be removed from the frame , the opposite end 38 is pulled out of slot 39 . this motion is permitted by the pivotal connection of end 37 within block 33 . with retainer 32 pivoted out of the way , after tray 22 is placed in a fully opened condition on a horizontal surface , all of the instruments or appliances loaded in frame 28 of the tray 22 then become accessible and can be easily lifted out of the aligned recesses . the instruments in frame 28 of tray 21 become accessible once tray 22 is opened as this lifts retainer 32 off of these instruments . the front wall 35 of each retainer frame 28 is offset with a raised portion 42 and a lower portion 43 . the pivot block 33 fits within a relief notch 42a ( not visible in fig2 see the lower retainer frame in fig1 ) and is riveted to the raised portion of frame 28 in tray 22 . pivot block 33 is mounted near the geometric center of the retainer frame 28 between the opposite end walls 29 and 30 . it is to be noted that the two retainer frames are positioned in an identical fashion in their corresponding trays 21 and 22 causing the frame edges to be aligned when the trays are closed together . the two frames are fashioned in an identical manner even though only one receives retainer 32 . this identical construction permits the use of a single frame style regardless of the tray to which it is assembled . this positioning enables the two trays 21 and 22 to close together securely without interference and for a single retainer 32 to be used for clamping both sets of dental instruments . the two trays are hinged together by continuous hinge 44 and the hinge flanges 45 and 46 are bent back relatively to the longitudinal axis of pivot pin 47 to enable the inner edge of the hinge knuckle to be positioned nearly flush with the outer rear surface 48 of each tray . the hinge knuckle is mounted with minimum clearance , just enough to permit the tray halves to be fully opened and lay flat on the same horizontal surface . flange 45 is riveted to the rear wall 36 of tray 21 and flange 46 is riveted to the rear wall of tray 22 . while the three rivet holes in tray 21 are not symmetrical between the tray ends or side walls , when one tray is turned relative to the other so as to create the clam - shell enclosure , the two sets of rivet holes will be staggered from each other . however , this particular stagger works well with the hinge design as is illustrated and thus the rivet holes in the hinge are provided in an offset manner to match the rivet holes in the two tray halves . it is still to be understood that the two trays are identical and the stagger is created when one is turned relative to the other . the hinge hole stagger also means that the rivet heads will not abut against each other when the cassette is fully opened and flat . this means that both tray halves 21 and 22 can lay flat and will not rock as might be the case if the rivet heads were in contact . trays 21 and 22 are fabricated without any flanges or sharp corners . the smooth , trim and compact nature of cassette 20 is illustrated in fig3 through 7 . these drawing figures also illustrate the number , shape and spacing of steam holes 49 . trays 21 and 22 are fabricated out of an aluminum alloy by a drawing process after which the edges are pinch trimmed . nc milling is used to establish the finished height of each tray . a two - station perforating die is used for the oblong steam holes . horn dies are used to punch the latch holes and rivet holes . the abutting edges 50 and 51 of trays 21 and 22 , respectively , are smooth and flat enabling a tight fit of the two trays when they are hinged and closed together . the drawing process enables the rounded corners for each tray and the use of a hinge precludes the need for a separate or detachable lid . the slide latch precludes the need for any flanges that would typically be used for securing latches or spring clamps . the result of this combination is a very smooth , efficient and compact design which provides maximum appliance or instrument density . while the invention has been illustrated and described in detail in the drawings and foregoing description , the same is to be considered as illustrative and not restrictive in character , it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected .
a metal autoclave cassette for dental instruments and appliances includes a pair of identical tray halves which are free of any outwardly extending flanges and which are provided with rounded corners and corner edges . each tray half includes a retaining frame which is riveted in place and which includes a plurality of aligned recesses in the opposite ends . the recesses are used for the receipt of the elongate dental instrument &# 39 ; s and a hold down mechanism clamps the instruments into position yet is easily moved out of position to provide access to the dental instruments .