embodiments of the separable rotary tool adapter according to the present invention will now be described with reference to the drawings . as shown in fig1 and 3 , the separable rotary tool adapter consists of a bent low - speed rotary unit a ( or a straight low - speed rotary unit ( not shown )) constituting an adapter body and joined detachably to a head of a machine tool , for example , a turret of a turret lathe , and a high - speed rotary unit b attached interchangeably to the low - speed rotary unit a . first , the bent low - speed rotary unit a will be described . as shown in fig2 a casing for the low - speed rotary unit a consists of a hollow rectangular cross - sectionally square casing member 1 , and a cylindrical casing member 2 formed so as to project from one surface of the casing member 1 , and the hollow interior portions of these casing members communicate with each other . a first rotary shaft 3 is inserted in the cylindrical casing member 2 in the axial direction thereof and is supported rotatably on ball - and - roller bearings 4 , 4 . a second rotary shaft 5 is inserted in the square casing member 1 and supported rotatably on a bearing 6a fitted in an opening at the front end of the hollow interior of the same casing member 1 and a bearing 6b fitted in an opening at the base end of the hollow interior of the same casing member 1 and pressed inwardly by a cover 13 ( which will be referred to later ). a bevel gear 7 mounted fixedly on the front end portion of the first rotary shaft 3 and a bevel gear 8 mounted fixedly on an intermediate portion 5a of the second rotary shaft 5 are meshed with each other . the front end surface of the bearing 6a is set back from that of the square casing member 1 , i . e . a high speed rotary unit mounting surface thereof by a distance m 1 . a description of this feature will be given later . the base end portion of the first rotary shaft 3 projects outward from the cylindrical casing member 2 so as to be joined to a driving shaft in a head of a machine tool . at the front end portion of the second rotary shaft 5 , planetary roller driving members projecting outward from the square casing member 1 , for example , planetary roller driving retainers 9 or planetary roller driving shaft pins 10 , are fixed thereto detachably with a bolt 11 . the retainers 9 or planetary roller driving shaft pins 10 are formed in a projecting manner in parallel with the axis of the second rotary shaft and arranged in the circumferential direction thereof at regular intervals so as to be opposed to planetary rollers , which will be described later , in the high - speed rotary unit b . covers 12 , 13 are attached to assembling openings formed at the portion of the square casing member 1 which is opposed to the inner end surface of the first rotary shaft 3 , and at the portion of the casing member 1 which corresponds to the base end of the second rotary shaft 5 , respectively , and threaded bores 14 , 14 . . . for use in fastening the high - speed rotary unit to this casing member are made in four corner portions of a high - speed rotary unit mounting surface thereof from which the planetary roller driving members project . a straight low - speed rotary unit ( not shown ) will now be described . this low - speed rotary unit has only a cylindrical casing member 2 of a bent low - speed rotary unit a , and a second rotary shaft 5 and bevel gears 7 , 8 are omitted . a first rotary shaft 3 is extended , and planetary roller driving members projecting outward from the cylindrical casing member 2 in the same manner as in a bent low - speed rotary unit are fixed detachably to the front end portion of the first rotary shaft with a bolt 11 . the high - speed rotary unit b will now be described . as shown in fig3 and 4 , a casing 15 for the high - speed rotary unit b has a stepped hollow cylindrical body , and a flange 17 ( for example , a square flange shown in fig5 ) is formed at the end of a larger - diameter portion 16 on the side of the base end thereof . a hollow interior of the casing 15 consists of a larger - diameter bore 18 on the side of the base end thereof , and a smaller - diameter bore 19 on the side of the front end thereof , and a rotary shaft 20 is inserted in the casing 15 in the axial direction thereof and supported rotatably on ball - and - roller bearings 21 , 21 in the smaller - diameter bore 19 . the base end portion of the rotary shaft 20 which is in the larger - diameter bore 18 in the hollow interior of the casing 15 constitutes a sun roller 22 in a planetary roller speed - increasing mechanism , and a socket 23 with which a rotary tool is engaged is formed in the front end portion , which projects from the opening of a cover 38 at the front end of the casing 15 , of the rotary shaft 20 . a suitable number of planetary rollers 25 , 25 . . . , for example , three or four planetary rollers are fitted between the inner circumferential surface , i . e . a raceway surface of a race 24 , which is fitted firmly in concentric relation with the sun roller 22 in the larger - diameter bore 18 in the hollow of the casing , and the outer circumferential surface of the sun roller 22 . the planetary rollers 25 are positioned and restrained in the axial direction thereof between an annular spacer 27 fitted firmly in a stepped bottom portion 26 of the larger - diameter bore 18 in the hollow interior and a roller holding ring 29 fitted firmly in a stepped portion 28 of the opening of the larger - diameter bore 18 or a holding ring 34 fitted in the larger - diameter bore 18 . in the case where the planetary roller driving members in the low - speed rotary unit a consist at least of planetary roller driving pins 10 , the planetary rollers 25 are provided therein with axially extending pin insert bores 30 . ( in the case where the planetary roller driving members consist of planetary roller driving retainers 9 , the pin insert bores 30 may or may not be provided .) in order to join the high - speed rotary unit b to the relative mounting surface of the bent low - speed rotary unit a , the bolts 32 inserted into the bolt holes 31 , 31 as shown in fig3 and 5 , which are made in the flange 17 in the high - speed rotary unit b so as to extend in the axial direction thereof and so as to be spaced at 90 ° intervals in the circumferential direction thereof , are screwed into the threaded bores 14 in the high - speed rotary unit mounting surface , so that the planetary rollers 25 engage the planetary roller driving members . when the planetary roller driving shaft pins 10 are employed , they are inserted in the pin insert bores 30 in the planetary rollers 25 , and when the planetary roller driving retainers 9 are employed , they are inserted in the clearances among the planetary rollers 25 . as a result , the end surface of the flange 17 in the high - speed rotary unit b is opposed to the front end surface of the square casing member 1 in the bent low - speed rotary unit a , i . e . the high - speed rotary unit mounting surface . during the assembling of this structure , the following means are adopted for firmly fitting the race 24 in the larger - diameter bore 18 in the hollow . in the first example , the outer end surface of the race 24 projects slightly from the stepped portion 28 of the opening of the larger - diameter bore 18 and contacts the roller holding ring 29 as shown in fig3 . the outer end surface of the roller holding ring 29 the inner end surface of which contacts the outer end surface of the race 24 projects by a distance m 2 from the end surface of the flange 17 of the casing 15 , and this distance m 2 is larger than the set - back distance m 1 already mentioned of the front end surface of the bearing 6a in the bent low - speed rotary unit a by a holding margin δ . it is necessary that the holding margin δ be set to not lower than a predetermined level so as to fix the race 24 reliably . if , however , the holding margin δ is too large , distortion occurs in the race 24 , and , therefore , it is set to 5 - 40μ . during the combining of the bent low - speed rotary unit a with the high - speed rotary unit b , the bolts 32 are tightened to cause the roller holding ring 29 to be fitted in the opening at the front end of the hollow interior of the square casing member 1 and engage the outer end surface of the outer race of the bearing 6a in the bent low - speed rotary unit a . consequently , the race 24 is pressed by the outer race of the bearing 6a via the roller holding ring 29 by a distance corresponding to the holding margin δ , whereby the race 24 is fixed . in the second example , the stepped portion 28 of the opening is not formed in the larger - diameter bore 18 ; an annular projection 33 coaxial with the opening of the larger - diameter bore is formed on the end surface of the flange 17 as shown in fig4 . the race 24 is fitted in the larger - diameter bore 18 in the condition that the former is held between the annular spacer 27 and holding ring 34 . bolt holes 35 extending axially through the annular spacer 27 , race 24 and holding ring 34 are provided at circumferentially spaced regular intervals , and threaded bores 36 are provided corresponding to these bolt holes in the stepped bottom portion 26 of the larger - diameter bore 18 . the annular spacer 27 , race 24 and holding ring 34 are tightened unitarily with the bolts 37 screwed to the threaded bores 36 , so that the race 24 is fixed . since the depth of the larger - diameter bore 18 is larger than a total thickness of the annular spacer 27 , race 24 and holding ring 34 , the head portions of the bolts 37 do not project from the end surface of the annular projection of the casing 15 . due to the existence of these bolt holes 35 , the surface of the race 24 is deformed at the portions thereof which correspond to the bolt holes while the planetary rollers 25 roll on this surface but , if the number of the bolt holes 35 and threaded bores 36 is set larger or smaller than that of the planetary rollers 25 by an odd number ( 1 , 3 . . . ), an adverse effect occurring when the planetary rollers 25 pass the deformed portions of the surface of the race decreases . during the combining of the bent low - speed rotary unit a with the high - speed rotary unit b , the bolts 32 are tightened to cause the annular projection 33 to be fitted in the opening at the front end of the hollow interior of the square casing member 1 , the front end surface thereof to engage the outer end surface of the outer race of the bearing 6a in the bent low - speed rotary unit a , and the end surface of the flange 17 to be opposed to the high - speed rotary unit mounting surface . there are in practice various types of low - speed rotary units , and the set - back distance m 1 of the front end surface of the bearing 6a of each low - speed rotary unit a is not uniform . therefore , in the first example , the distance m 2 by which the roller holding ring 29 projects is regulated on a job site so as to obtain a predetermined holding margin but , in the second example , this regulating operation is not required . a cover member 38 at the front end of the casing 15 in the high - speed rotary unit b serves as a holding member for the ball - and - roller bearings 21 , 21 . in the first example shown in fig3 the cover member 38 is fastened to the front end surface of the casing 15 with bolts , while , in the second example shown in fig4 the cover member 38 is engaged with a threaded portion 39 at the opened side of the smaller - diameter bore 19 in the casing 15 . in the latter case , the screwing direction of the cover member 38 is set in agreement with the rotational direction of the rotary shaft 20 for preventing the cover member from being loosened while the adapter is in use , and the cover member is ready to be turned in the tightening direction due to a seal contacting the same . the combining of the straight low - speed rotary unit with the high - speed rotary unit b is also done in the same manner as mentioned manner . the separable rotary tool adapter in which the low - speed rotary unit and high - speed rotary unit are combined unitarily is set on a rotary tool mounting portion of a machine tool , for example , such a portion of a turret in a turret lathe . during this time , the first rotary shaft 3 is joined to the driving shaft in the turret , and the base end portion of the cylindrical casing member 2 of the low - speed rotary unit a is fixed to the turret , a suitable rotary tool being engaged with the socket 23 at the front end portion of the second rotary shaft 5 . when the driving shaft in the turret is rotated with a bent low - speed rotary unit a joined to the high - speed rotary unit , the second rotary shaft 5 is rotated via the first rotary shaft 3 and bevel gears 7 , 8 . namely , the planetary roller driving retainers 9 or planetary roller driving shaft pins 10 revolve around the axis of the second rotary shaft 5 , so that the planetary rollers 25 revolve around the same axis as they roll on the inner circumferential surface of the race 24 . owing to the planetary rollers 25 revolving around the axis of the rotary shaft 5 and rotating on their own axes , the sun roller 22 is rotated at an increased speed which is higher than the rotational speed of the second rotary shaft 5 . as a result , the rotary tool is rotated at a speed higher than that of the driving shaft in the turret , and carries out the processing of a workpiece . when the driving shaft in the turret is rotated with a straight low - speed rotary unit joined to the high - speed rotary unit , the first rotary shaft 3 is rotated . namely , the planetary roller driving retainers 9 or planetary roller driving shaft pins 10 revolve around the axis of the first rotary shaft 3 , so that the planetary rollers 25 revolve around the same axis as they roll on the inner circumferential surface of the race 24 . consequently , the rotary tool is rotated at a speed higher than the rotational speed of the driving shaft in the turret and processes a workpiece in the same manner as the rotary tool on the adapter employing the bent low - speed rotary unit a . a turret lathe can be used correspondingly to the direction in which the surface ( outer circumferential surface and an end surface ) to be processed of a workpiece faces , by using the bent low - speed rotary unit a and straight low - speed rotary unit interchangeably with the high - speed rotary unit b used in common . the size of each portion of the high - speed rotary unit b is varied in accordance with the dimensions of the space in the turret and the sizes and rotational speeds of the rotary tools . if such variously - sized high - speed rotary units b are available , they can be used suitably for various dimensions of the space in the turret in a turret lathe and various sizes and rotational speeds of rotary tools by changing one rotary unit b to another and fixing the resultant rotary unit b to a single low speed rotary unit a with the bolts 32 removed from and driven into the rotary units b , a . moreover , if various sizes of planetary roller driving members , i . e . planetary roller driving shaft pins 10 or planetary roller driving retainers 9 are used by changing one type of driving members to another and installing the resultant driving members with the bolts 11 removed from and driven into the rotary shaft 5 , the specifications can be further diversified . the above - described separable rotary tool adapter can be used for any direction in which the surface ( an outer circumferential surface and an end surface ) to be processed of a workpiece in a machine tool , for example , a turret lathe faces , by using the bent low - speed rotary unit and the straight low - speed rotary unit selectively and the high - speed rotary unit in common . the size of each portion of the high - speed rotary unit is varied in accordance with the dimensions of the space in the turret and the sizes and rotational speeds of the rotary tools . if such variously - sized high - speed rotary units are available , they can be used suitably for various dimensions of the space in the turret in a turret lathe and various sizes and rotational speeds of rotary tools by changing one high - speed rotary unit to another and fixing the resultant high - speed rotary unit to a single low - speed rotary unit . therefore , the separable rotary tool adapter according to the present invention can be applied to various types of machine tools and various kinds of high - speed processing operations by a combination of a low - speed rotary unit and a high - speed rotary unit without providing a lot of special rotary tool adapters of various specifications . while the present invention has been described above with respect to a typical preferred embodiment thereof , it should , of course , be understood that it should not be limited only to them but various changes or modifications may be made without departure from the scope of the invention as defined by the appended claims .