Divided milling cutters
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in part of my prior U.S. patent application Ser. No. 455,825, filed Jan. 5, 1983, now U.S. Pat. No. 4,552,496. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to such two-part tools, particularly milling cutters. 
     Divided milling cutters of the type to which this invention relates are utilized particularly in the wood working industry, e.g. for tonguing or grooving or alternatively simultaneous round-planing or bevelling of two opposing edges of boards and the like. 
     When boards of another thickness than previously are to be planed, one will have to change the distance between the first (upper) milling cutter half and the second (lower) milling cutter half. A traditional way of carrying out this operation (so called &#34;setting&#34;) involves inserting or removing of a greater or smaller number of spacing washers, each having a greater or smaller thickness, between the two cutter halves. This setting operation is tedious and time consuming, since a plurality of bolts have to be unscrewed and tightened again, and it can not be carried out without previous removal of the milling cutter head from the cutter spindle. Another drawback resides therein that the distance adjustment can not be made step-less or continous. 
     Such divided milling cutters and similar two-part tools may be removably secured to a rotating spindle either by purely mechanical means or hydraulically. Examples of milling cutters of the first kind are disclosed in the Swedish Pat. No. 19595, the U.S. Pat. No. 987,391  to Mitchell and in my abovementioned U.S. patent application. An apparatus in which tools, such as cutter halves, may be hydraulically clamped to a rotational spindle froms the subject matter of the U.S. Pat. No. 4,244,248 to Adell et al. This apparatus comprises a double walled sleeve which is formed with means for providing a pressure in a recess formed between the outer wall and the inner wall of the sleeve and for releasing the pressure from said recess. One or more cutter halves or similar having center bores fitting the outer dimension of the sleeve are slipped onto the sleeve, whereupon the sleeve together with the tools are slipped onto a rotatable spindle, and a pressure medium inside the recess of the sleeve is pressurized, whereby the two walls of the sleeve are subjected to a radially inwards and outwards directed pressure providing some expansion outwards and inwards respectively of the said walls, whereby the sleeve, the rotatable spindle and the tools are interconnected. The tools are clamped between abutment means on axially opposite sides of the tools, spacers in the shape of distance sleeves being interposed between the tools and also between each tool and its adjacent abutment means. When the mutual distance between the tools has to be changed it is necessary to dismount the whole apparatus and substitute other distance sleeves for the previous ones. This substitution can not be carried out without removing the entire apparatus from the spindle. 
     SUMMARY OF THE INVENTION 
     In view of the above circumstances the principal object of the invention resides in providing a divided milling cutter or similar tool with setting means which permits continous adjustment of the distance between the tool halves while they remain on the spindle, and which in addition hereto is easy to manipulate and to keep clean. 
     This object is attained thanks to the fact that the two-part tool is so designed as is set forth in the specification. 
     Further features and advantages of the tool according to the invention will become apparent from the following detailed description and the annexed drawings which diagrammatically and as non-limiting examples illustrate two preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial, simplified, exploded, longitudinal sectional view of a first embodiment of the invention in which hydraulic locking of the cutter halves is utilized. 
     FIG. 2 is a more detailed view of one of the sleeves comprised in the two-part tool or divided milling cutter according to the invention. 
     FIG. 3 is a perspective view of a divided milling cutter according to a second embodiment of the invention. 
     FIG. 4 is a side view, partly in section, of the embodiment according to FIG. 3. 
     FIG. 5 is an end view of the divided milling cutter according to FIGS. 3-4 as seen from the left in FIG. 4. 
     FIG. 6 is an end view of the divided milling cutter according to FIGS. 3-4 as seen from the right in FIG. 4. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The apparatus shown in FIGS. 1 and 2 of the drawings comprises a first, inner sleeve 1 which is intended to be secured to a milling cutter spindle 9 and is to be rotated together with the spindle. The inner sleeve 1 is a hydraulic sleeve which is double or slotted and comprises two hardened steel sleeve portions 1a, 1b which are united with each other at their ends as shown at 1c  and 1d. The sleeve portions 1a, 1b are separated by an annular slot or chamber 1e which is filled with oil, grease, or the like which acts as a pressure medium. Chamber 1e is provided with an inlet 19 and an outlet 20 for the pressure medium. On the main, cylindrical portion of the sleeve 1 there is mounted a first, exchangeable milling cutter half 2 which is shown only in part and is shown as abutting the upper (in FIG. 1), annular surface 1f of the flange portion 1g of the sleeve 1. The cutter half 2 is slipped on to the inner sleeve 1 which it surrounds with a small clearance, e.g. a slight slip fit. 
     The cutter half 2 carries a first set of cutting edges 4 of which only one is shown. The cutting edges 4 of the first cutting half 2 cooperate with a second set of cutting edges 5 of which only one is shown. The cutting edges 5 are carried by a second milling cutter half 6 which is exchangeably secured to an outer sleeve 8 by means of screws 7 (merely indicated). To make the drawing clearer the outer sleeve 8 is not shown in its operative position but displaced axially upwards, above the sleeve 1. In the illustrated embodiment the sets of cutting edges 4,5, which are angularly staggered or displaced with respect to each other, are intended for the rounding or bevelling of two opposite, longitudinal edges of a board or deal which may be about 25 mm in thickness. This means that the cutting-edges 4,5 are located considerably closer to each other than shown in FIG. 1. 
     The lower end of the sleeve 8 in FIG. 1 has an annular flange which is directed radially inwards and encircles an opening 10 which is coaxial with the sleeve 1 and has an insignificantly larger diameter than the tubular principal portion of the sleeve 1 which penetrates into the sleeve 8 through this opening. 
     On its entire inside the sleeve 8 is provided with an internal thread 11 which has a predetermined lead, e.g. 1 mm. Cooperating with this thread 11 is an external thread 12 on a third, intermediate sleeve which is generally designated 13. The main, tubular portion of the intermediate sleeve 13 has an inner diameter which is insignificantly greater than the outer diameter of the tubular portion of sleeve 1, so that the sleeve 13 may be slipped or threaded on thereto. Sleeve 13 also has an annular flange 14 which is directed radially inwards and defines an opening 15 having a diameter which substantially equals the inner diameter of the inner sleeve 1. In its operative working position sleeve 13 rests upon the end of the sleeve 1 by means of its annular flange 14. This annular end surface 1h constitutes a reference surface. 
     It is obvious that the outer sleeve 8 and accordingly also the second cutter half 6 and its set of cutting edges 5 are displaced axially when the intermediate sleeve 13 is rotated manually or by means of a suitable tool cooperating with a pair of diagrammatically indicated recesses 16 in the upper end surface of the sleeve 13. An axially extending groove only shown in FIG. 2, in which a scale or graduation 17 is provided, is milled or manufactured in another way in the internal thread of the outer sleeve 8. This scale indicates the displacement of the sleeve 8 from a predetermined reference or initial position, e.g. when the upper end surface of the sleeve 8 is located in the same plane as the upper end surface of the intermediate sleeve 13, said plane being perpendicular to the common centre axis of the spindle 9 and the sleeves. This upper surface of the sleeve 13 may be provided with an arrow or another designation which cooperates with a scale of fractions of a revolution on the upper surface of the sleeve 8. With a lead e.g. of 1 mm according to the above, a rotation of 31/4 revolutions of the intermediate sleeve 13 corresponds to an axial displacement of 3.25 mm of the outer sleeve 8 in relation to the inner sleeve 1. 
     When mounting the tool on the spindle 9 the inner sleeve 1, the first cutter half 2 with the first set of cutting edges 4, the outer sleeve 8 with the appurtenant second cutter half 6 and the second set of cutting edges 5, and the intermediate sleeve 13 are pushed or slipped on to the spindle 9. Then, the desired spacing between the cutter halves 2, 6 is set by rotating the intermediate sleeve 13 the proper number of turns and fractions of turns as described above, which is a very simple operation thanks to the present invention. Finally the parts of the tool are clamped or locked to the spindle 9 and centered with respect thereto in their respective, desired position. Such locking is carried out by pressurizing the annular chamber 1e by pressing oil, grease or the like into said chamber through the inlet 19. Hereby the sleeve 1 expands radially, the inner wall 1a being pressed against the spindle 9 and the outer wall being pressed against the sleeves 8 and 13, and the cutter halves 2 and 6. 
     As is apparent from the above, it is also very easy to change the distance between the two sets of cutting edges 4 and 5, respectively, in the apparatus according to the invention, when this is required. Such change or adjustment setting may be carried out even without removal of the divided cutter from its cutting spindle 9, simply by depressurizing the annular chamber 1e by means of the outlet 20 and subsequent rotational displacement of the sleeve 13 and consequent axial displacement of the sleeve 8. 
     A second embodiment of the invention is illustrated in FIGS. 3-6, in which the same reference numerals as in FIGS. 1-2 have been utilized to designate same or similar parts. 
     In this second embodiment the hydraulic sleeve 1 is supplemented with a ring or collar 20 which closely surrounds the cylindrical, main portion of the hydraulic sleeve 1 and is secured to the flange portion of sleeve 1 by means of bolts 21 while leaving a gap or interspace therebetween. In this gap the inturned annular flange 13b of the second sleeve 13 is engaged. This sleeve is an outer sleeve in this embodiment and is accordingly provided with internal threads 12. These threads are in engagement with outer threads on the third sleeve 8 which constitutes the intermediate sleeve in this embodiment. The intermediate sleeve 8 is on one hand non-rotatably connected to the collar 20 by means of locking pins 27 and on the other hand rotatable with respect to the outer sleeve 13. The second cutter half 6 is bolted to the intermediate sleeve 8 by means of bolts 22. The rotational or angular position of the outer sleeve 13 with respect to the inner sleeve 1 as well as the intermediate sleeve 8 and the second cutter half 6 is indicated by a scale 28 (FIG. 5) on the flange 13b and an index 29 cooperating therewith on the flange portion of the inner sleeve 1. 
     The first cutter half 2 is comprised of three individual parts 2a, 2b and 2c in this embodiment. These parts have the same internal diameter and surround the cylindrical portion of the hydraulic sleeve 1 with a minute clearance, e.g. a slight slip fit. The first part 2a, to which the set of cutting edges 4 are secured, is bolted to the second, intermediate part 2b by means of threaded bolts or screws 23. On the other hand the intermediate part 2b is secured to the third, outer part 2c by means of threaded bolts 25 and cooperates with this outer part by means of a common, frusto-conical inter-engagement surface 24. Thanks to their conical surfaces 24 the intermediate part 2b and the outer part 2c act as a locking device for the cutter half 2 even though the chamber 1e of the hydraulic inner sleeve 1 is not pressurized. 
     The embodiments described above and illustrated in the drawings are, of course, to be regarded merely as nonlimiting examples and may as to their details be modified in several ways within the scope of the following claims. In particular, the invention may be applied not only to milling cutters but also to any other two-part tool.