NO TOOL DETECTION SYSTEM AND TOOL HOLDER arrow 12 indicating conventional type of reciprocal feed
movement which may be employed and the numeral 13 BACKGROUND OF THE INVENTION designating the direction of rotation of said spindle.
In applicant's earlier issued U.S. Pat. No. 3,381,550 dated Said spindle has a bore 14 and projected there into the radiMay 7, 1968, entitled, "Apparatus For A Tool Failure Detec- 5 al key 15 which registers with a corresponding key-way 16 tion System," there was provided a compensating type of tool within the shank 17 of too1 holdeT 18
holder including a pair of relatively moveable parts. In that Adjusting nut 19 is mounted over said shank and secured in construction, a radioactive element was mounted upon one of desired position by set screw 20.
the relatively movable parts, and a shielding device normally )n Secondary set screw 21 projects radially inward through covering the radioactive element was mounted upon the other 1U said spindle and engages the tapered portion 22 of said shank part. A failure of contemplated function of the tool in the as one means of effectively locking the tool holder shank machine tool was adapted to cause a relative movement within said spindle for rotative drive as desired, between the parts such as would uncover the radioactive ele- The tool holder adjacent one end has a bore 23 terminating ment to activate a radiation detection system for avoiding 15 in a counterbore 24 of slightly smaller diameter adapted to damage to a workpiece, to give an audible or visible signal. It cooperatively receive the shank 25 of the cutting tool adapter was designed to prevent damage to workpieces on a produc- 26.
tion line which might not otherwise be discovered until after a Said adapter is of a generally conventional construction incomplete machining operation with consequent loss and ex- eludes the transverse locking screw 27 and the drive key 28 pense. 20 an(* 's removabty inserted within the tool holder with the
In accordance with the present invention, the same princi- shank 25 projected snugly into the bore 24 and loosely into pie may be employed in a device to detect the presence auto- tne bore 23 as shown in FIG. 1.
matically of "no tool," "a broken tool" or an "improperly set A series of transverse ball receiving bores 29 are formed tool" for taps, drills, reamers, boring tools, counter bores and through the wall of said holder and communicate with bore 23 milling cutters and give an instantaneous signal by which the 25 and are adapted to movably nest the shank retaining balls 30 machine tool or production line may be shut down until a whose inward adjustment for anchoring the shank is limited to proper tool is provided. the positioning shown in FIG. 1.
It is an object of the present invention to provide an im- The shank has an annular locking groove 31 whose outer proved tool holder whereby upon the existence of either "no walls are tapered outwardly and are in retained registry with tool," "a broken tool'? or an "improperly set tool" after a 30 the respective balls 30, of which there are three in the illustrapredetermined feed movement of the tool holder and a shell tive embodiment.
such as would normally be caused by engagement of a One of the tapered surfaces corresponding to said groove 31 properly set tool with respect to the workpiece to activate a is in the nature of a cam 32 adapted to disengage the balls radiation detection system and for automatically shutting from the recess 31 to permit withdrawal of the shank 25 and down the equipment. 35 adapter 26 when the surrounding shell 40 has been moved Ion
It is a further object to incorporate in the present system gitudinally so that its internal annular recess 43 is in registry and in conjunction with such tool holder, an electrical circuit with the balls as hereafter described.
which includes a radiation detection system which circuit is The tool holder at the end of bore 23 has a counterbore 33 normally closed and incorporating a limit switch or the like terminating in an axial threaded aperture into which is prowhich is mechanically or electrically opened upon such nor- 40 jected the threaded end of bolt 34. Said bolt extends axially mal feed movement of the tool holder which with a normal outward within counterbore 33 and terminates in the enlarged tool properly set would otherwise compressively engage the head 35. Coiled compression spring 36 surrounds bolt 34 and workpiece so that relative movement of the workpiece holder bears against a portion of the tool holder at the base of counparts would cause a Shielding of the radioactive element. terbore 33.
The detail of construction for the mounting and protectively 45 The other end of spring 36 bears against the inturned stop enclosing of a radioactive ring upon a tool holder is set forth in flange 37 of the pressure pad 38 with the headed portion of applicant's copending U.S. Pat. application, Ser. No. 489,522 the bolt 34 extending up into the bore 39 of said pressure pad. filed Sept. 23,1965. In the assembled position of the adapter shank 25 within the
It is another object to provide an improved tool holder tool holder, the inner end of said shank is compressively enwhich mounts a radioactive element in a very simple construe- gaged by the pressure pad 38 which is normally biased outtion which includes a shell mounted over the tool holder and wardly by the spring 36 thereby placing tension at all times normally biased so as to expose the radioactive element and upon said shank; said coil spring being in compression with the which upon contact of a tool within the tool holder with a adapter inserted as shown in FIG. 1.
workpiece with the tool properly set will cause such relative ^ Mounted over and surrounding the outer portion of the tool movement of the shell with respect to the tool holder as to holder is a shell 40 which has an annular groove 41 providing a protectively enclose the radioactive element. grip to facilitate retraction of said shell manually.
These and other objects will be seen from the following Said shell includes the bore 42 which snugly and slidably specification and claims in conjunction with the appended receives tool holder 18 and formed within said bore is the andrawing in which: 0q nular counterbore or ring groove 43 by which with the shell
FIG. 1 is a longitudinal section of the present tool holder de- retracted and in registry with the balls 30, outward manual tection device with the power and feed spindle and workpiece forces applied to the shank 25 will cam the balls into the fragmentarily shown. recess 43 and permit withdrawal of the tool adapter 26 and its
FIG. 2 is a schematic diagram of the electrical circuit of the shank 25 from the tool holder, radiation detection system. 65 The interior surfaced of the shell has an elongated addi
nci-Aii m ... tionai counterbore 44 which defines the shoulder 45 at the
DETAILED DESCRIFI ION forward end thereof as shown in the drawing.
The present "no tool," "broken tool" or "improperly set The compression spring 46 is nested within the bore 44 and tool" detection device is generally indicated at 11, FIG. 1 engages the shoulder 45 at one end and at its opposite end, enmounting a cutting tool T such as may be used with taps, drills, 70 gages the washer 48 anchored by the snap ring 47 mounted reamers, boring tools, counterbores, milling cutters and the upon the tool holder.
like. The shell intermediate its ends has an internal shoulder cor
The cutting tool T is shown spaced from the workpiece W, responding to the inner end of the bore 44 by which upon enfragmentarily shown, said tool holder being mounted within a gagement with the ring 47 limits relative outward movement conventional type work driving and feeding spindle S, the 75 of said shell to the position shown in FIG. 1. A central portion