Abstract:
A tool damage detection device which detects the presence or absence of damage, has a contact bar rotatably supported on a casing; a pneumatically operated air drive device operatively connected with a supply of air under pressure; and a linear-to-rotational motion conversion device operatively interconnects the contact bar and the direct-air drive device. A resilient member is interposed between the contact bar and the conversion device.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
   The present invention relates to a tool damage detection device or the like. 
   An example of a conventional tool damage detection device is disclosed in Japanese Patent Publication No. TOKKAI 2001-38512. As shown in  FIG. 6 , this detection device is such that an electric motor  50  is used to detect whether or not a contact bar  51  contacts a body part of a tool  52  which lies within an arc of the contact bar  51 . When the contact bar  51  passes without contacting the body part of the tool  52 , the electric motor  50  senses this as a “damage” situation, and outputs a warning or a stop signal to a machine control section (not shown in the figure). 
   However, the above-mentioned detector is often used under circumstances wherein a great amount of cutting agents (liquid) come into contact with the detector, or a mist of cutting agent is filled in the air. Since the cutting agents contain considerable amounts of surfactant, they exhibit extremely high permeability and causticity characteristics. As a result, it is necessary to improve the waterproofing of a bearing of the detector. To do this, it is necessary to provide increased amounts of waterproofing which include the use of rubber O-rings, packing, V-seals and so on. However, these measures induce a shortcoming that the resulting friction resists the rotation of the contact bar and the torque output is reduced. 
   Also, in the case of the above-mentioned detector, since the cutting agents contain surfactants, they exhibit high levels of permeability and causticity. As a result, the durability of the control motor is significantly reduced due to problems such as failure of the motor coil winding insulation or heat generation due to electric overload. Moreover, an expensive electric control section is required. Additionally, detection of any damage (chipping) due to contact with the edge (slope portion) of the tool which lies within the range of the turning of the contact bar, is almost impossible. 
   The present invention has been proposed in order to solve the above-mentioned problems. The object of the present invention is, therefore, to provide a tool damage detection device which can detect damage of the body part or edge of the tool without problem occurring due to the penetration of the cutting agents or electric overload which result from the provision of waterproofing measures. 
   Further objects and advantages of the invention will be apparent from the following description of the invention. 
   SUMMARY OF INVENTION 
   In order to achieve the above-mentioned purpose, a tool damage detection device according to a first aspect of the present invention detects the presence or absence of damage through the contact of a contact bar which projects in an orthogonal direction from a rotational axis projecting from the main body case, with a tool, and outputs a signal when damage is detected. The rotational axis is rotated by a direct-acting air driving (pneumatically operated) device, so that the durability of the tool damage detection device is not affected by penetration of cutting agents. 
   Also, in the tool damage detection device according to a second aspect of the present invention, a resilient member such as a torsion spring is used to provide an operative drive connection between the rotational member on which the contact bar is supported and the pneumatically powered direct-acting air driving member. This provision enables impact between the tool and the contact bar to be attenuated. 
   In addition, in the tool damage detection device according to a third aspect of the present invention, a plunger type contact sensor which detects damage of an edge of the tool, is provided in an outboard end of an arm bar projecting in an orthogonal direction from the rotational axis projecting from the main body case. The tool damage detection device can detect the damage by the amount the edge of the tool is displaced with respect to a sensor contact face. 
   In the invention according to the first aspect, since the contact bar is rotated by the direct-acting air driving device, there is no need for an electrical control motor. As a result, there is no negative effect due to the penetration of the cutting agents (liquid) containing surfactants or the like. Therefore, the embodiments of the invention can be used without encountering the above mentioned types of problem even in circumstances wherein large amounts of cutting agents (liquid) come into contact with the detector or the detector is exposed to clouds of cutting agents which have been dispersed into the air. 
   Also, with the embodiments according to the second aspect of the invention, the rotational axis rotates with the sensor part detecting the rotational angle of the contact bar through the coil spring from the rotating member rotating by the direct-acting air driving member, and the contact bar contacts a body of the tool. As a result, the force with which the tool is contacted can be maintained at an adequate level while the impact with the tool can be decreased. 
   Moreover, with embodiments of the third aspect of the invention, a plunger type contact sensor provided in the arm bar projecting in the orthogonal direction from the rotational axis projecting from the main body case is rotated and stopped at the position corresponding to the edge of the tool. Therefore, these embodiments can detect the damage according to the amount of displacement which occurs until the edge of the tool contacts the sensor contact face. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional view of a device which in accordance with one embodiment of the present invention is provided with a vertically arranged direct-acting air driving member; 
       FIG. 2  is a perspective view of a rotating cam tube which converts the linear motion of the direct-acting air driving member into rotational motion; 
       FIG. 3  is an exploded perspective view of a device which in accordance with one embodiment of the invention is provided with a horizontally arranged direct-acting air driving member; 
       FIG. 4  is a perspective view showing a rack (and pinion) arrangement which converts linear motion of the direct-acting air driving member into rotational motion; 
       FIG. 5  is a sectional view of a third embodiment of the invention which uses a plunger type contact sensor; and 
       FIG. 6  illustrates a relationship between the rotation of a contact bar of a conventional device and a tool, which was discussed in the opening paragraphs of the instant disclosure. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Next, an embodiment of the present invention will be explained with reference to the drawings.  FIG. 1  is a sectional view of an embodiment of the invention which is provided with what shall be referred to as a vertically or axially acting direct-acting air driving;  FIG. 2  is a perspective view showing a rotating cam tube which converts the linear of movement of the direct-acting air driving member into rotational motion;  FIG. 3  is an exploded perspective view of an embodiment of the invention which is provided with what shall be referred to as a horizontally or laterally acting direct-acting air driving member;  FIG. 4  is a perspective view of a rack and pinion arrangement which converts the linear motion of the laterally acting direct-acting air driving member into rotational motion; and  FIG. 5  is a cross sectional view of the device with a plunger type contact sensor according to the present invention. 
   In  FIG. 1 , the numeral  1  denotes an embodiment of the invention which is provided with a vertically acting direct-acting air driving unit  3  which operates in an axial direction of a main case body or casing  2  and which is disposed below the casing  2 . The direct-acting air driving unit  3  allows a piston  6  to move upward against the bias of a spring  5  in accordance with pressurized air which is supplied through an air hose  4  that is communicated with a source of air under pressure such as an air compressor/valve arrangement (not shown in the figures). When the piston  6  moves upward, a piston or plunger  8  is driven upward via the connecting rod  7 . On the other hand, when there is no pressurized air supplied through the air hose  4 , the plunger  8  returns to its former position under the influence of the bias applied by spring  5 . 
   In  FIGS. 1 and 2 , the plunger  8  is shown to be connected with the piston  6  through the connecting rod  7  and a flexible joint  9  which absorbs any offset between the centers of the piston  6  and the plunger  8 . If offset is not an issue, then the plunger  8  can be connected with the piston  6  without the flexible joint  9 . 
   When the plunger  8  moves upward by actuation of the direct-acting air driving unit  3 , a roller  10  which is axially supported on the plunger  8 , drives a rotating cam tube  12  to rotate about an axis along which the plunger  8  is reciprocal, via engagement with a spiral (helical) cam groove  11  in which the roller  10  is received (slides) and thus functions as a cam follower. The rotation of the rotating cam tube  12  drives a rotatable member  14  to rotate. The rotatable member  14  is united with the rotating cam tube  12  through connecting means  13 . 
   The above-described rotatable member  14  drives a sensor drive shaft  16  to rotate through a connection which is established via a coil spring (torsion coil spring)  15 . The sensor drive shaft  16  projects out through an upper surface of the casing  2 . The upper end of the sensor drive shaft  16  is connected with a contact bar  18  which projects at right angles through a cap member  17  that covers the sensor drive shaft  16 . 
   The contact bar  18  is arranged to contact a body part (side face) of a tool  20  while it is rotating. The contact bar  18  is rotated by way of the torsion which is applied by the coil spring  15 , via the rotation of the rotatable member  14  which is induced by the direct-acting air driving unit  3 . This allows the sensor drive shaft  16  to detect the, rotational angle via the rotation of the contact bar  18  and the generation of contact force between the contact bar and the tool  20 . In this case, the contact bar  18  contacts the body part of the tool  20  with a relatively low contact force and thus reduces shock to the tool  20 . 
   The sensor drive shaft  16  is supported by the casing  2  through a bearing  19 . Also, a hub-like base portion  21  of the sensor drive shaft  16  has a drum-shape and encloses the rotatable member  14 . One end of the coil spring  15  is connected with the drum-like base portion  21 , and the other end is connected with the rotatable member  14  respectively. 
   The rotation of the rotatable member  14  rotated by the actuation of the direct-acting air driving unit  3  is transmitted to the sensor drive shaft  16  through the coil spring  15  as noted above. As a result of this structure, when the contact bar  18  contacts the body part of the tool  20  and stops, the rotatable member  14  continues to rotate only for a predetermined rotational angle with the rotating cam tube  12 . 
   A magnetic switch  22   a  and a magnet  22   b  are arranged to form a non-contact switch between the inner circumference of the casing  2  and the outer circumference of the base portion  21  of the drive shaft  16 . When the contact bar  18  does not contact the body part of the tool  20  in the middle of the rotation, the magnetic switch  22   a  and the magnet  22   b  senses it as “damaged”, and output a “damaged signal”. This signal output circuit is not shown in the drawings. On the contrary, when the contact bar  18  contacts the body part of the tool  20  in the middle of the rotation, the tool is judged as “normal”. 
   Top and bottom end portions of the rotating cam tube  12  are supported on the inner circumference of the casing  2  through bearings  23   a,    23   b,  so that smooth rotation is assured. A tube member  25  with a straight or linear groove  24  is provided on the outside of the rotating cam tube  12  (inner circumferential face of the casing  2 ). The straight groove  24  guides an external roller  10 ′ which has the same axis as the roller  10  axially supported by the plunger  8  in the vertical direction. The straight groove  24  of the tube member  25  may be formed directly on the inner circumferential face of the casing  2 . In addition, the straight line groove  24  is made in order to guide the plunger  8  in a vertical direction with the actuation of the direct-acting air driving unit  3 . However, it may be changed to another structure without departing from the scope of the invention. 
   The rotating cam tube  12  is rotated by moving the plunger  8  up and down with the actuation of the direct-acting air driving unit  3 . However, the rotational angle of the rotating cam tube  12  is determined by the sliding length (stroke) of the piston  6  of the direct-acting air driving unit  3 . The stroke is required to have a certain length because an angle of the spiral or helical groove  11  is increased in order to reduce resistance during the rotation. In this embodiment, the above-mentioned condition is also taken into account. 
   The non-contact switch consisting of a magnetic switch  26   a  and a magnet  26   b  is provided on a tube or sleeve member  25  which forms an outer wall of the rotating cam tube  12  and in which the linear groove  24  is formed. This enables the output of the positional signals representing an original (start) point and ending point of the rotation of the rotating cam tube  12 . In this instance also, the output circuit of the positional signals of the rotating cam tube  12  is not shown in the figure. 
   The direct-acting air driving unit  3  uses pressurized air to rotate the contact bar  18  toward a stop-end from the original point. The contact bar  18  rotates under the influence of the bias provided by the spring  5  between the stop-end and the original point. 
   However, when the direct-acting air driving unit  3  rotates toward the stop-end from the original point, spring force can be used, and air can be used between the stop-end and the original point. Also, the direct-acting air driving member can be replaced with a double-acting air driving machine. 
   A second embodiment of the invention is shown in  FIGS. 3 and 4 . In this second embodiment direct-acting air driving unit  3  is arranged to operate in the horizontal (i.e. lateral) direction with respect to the casing  2  as shown. The direct-acting air driving unit  3  in this embodiment advances a sliding member  27  in the direction of Y against the spring force of the spring  5  shown in  FIG. 4  by the air supplied through the air hose  4  communicated with the air compressor (not shown in the figures). When there is no air supply through the air hose  4 , the sliding member  27  returns to the former position under the bias of spring  5  which has become compressed by the pneumatically induced stroke. 
   When the sliding member  27  advances, the rotatable member  14  is rotated through a rack  28  forming the body part of the sliding member  27  and a pinion  29  which engages with the rack  28 . The rotatable member  14  continuously rotates the drive shaft  16  projecting from the upper surface of the casing  2  through the coil spring  15 . The drive shaft  16 , is connected with the contact bar  18  so that it projects at right angles through the cap member  17  covering the upper end of the drive shaft  16 . As in  FIG. 1 , when the contact bar  18  does not contact the body part of the tool  20  in the middle of the rotation, the contact bar  18  outputs the “damaged” signal. 
   The casing  2  shown in  FIG. 3 , consists of box-shaped upper and lower casing portions  2   a ,  2   b  which are positioned respect to one another by positioning pins  30  and corresponding pin holes (not shown in the figure). The upper and lower portions  2   a ,  2   b  are fixed by screw bars  31  in plural positions. As in  FIG. 1 , the casing  2  allows the contact bar  18  to rotate through the coil spring  15  from the direct-acting air driving unit  3  and generate the necessary contact force when the contact bar rotates to contact the tool  20 . Also, the casing  2  can reduce the shock to the tool quickly. 
   A third embodiment of the invention is shown in  FIG. 5 . In this embodiment, the arm bar is, which by way of example, comprised of a tubular member  33  and a plunger type contact sensor  35 . The arm bar  33  is connected to the sensor drive shaft  16  which projects out of the casing  2 , and projects in an orthogonal direction through a boss unit  32 . The plunger type contact sensor  35  detects the damage of an edge  34  (in this example, the sloping edge represents a cutting portion), by allowing the arm bar  33  to contact the edge  34  of the tool  20 . In addition, the edge (slope=cutting portion)  34  of the tool  20  is not limited to downwardly curving elements in the manner illustrated. 
   The rotational angle of the sensor drive shaft  16  is determined by the spiral or helical angle of the spiral groove  11  of the rotating cam tube  12  which is integrated with the rotational angle of the sensor drive shaft  16 . In other words, when the piston  6  moves up against the spring force of the spring  5  in response to pressurized air being supplied through the air hose  4  wherein the direct-acting air driving unit  3  is communicated with the air compressor (not shown in the figure), the plunger  8  is pushed up by way of the connecting bar  7 . As a result, the rotating cam tube  12  rotates in a horizontal direction through the spiral groove  11  wherein the roller  10  axially supported by the vertical axis  8  fits (slides). Also, the drive shaft  16  integrated with the rotating cam tube  12  rotates (revolves) in the horizontal direction only for a certain angle. 
   However, if the starting and ending points of rotation of the arm bar  33  projecting in the orthogonal direction through the boss unit  32  are predefined in the sensor drive shaft  16  during the actuation of the direct-acting air driving unit  3 , a center of a sensor contact face  35 ′ of the plunger type contact sensor  35  with the arm bar  33  can be precisely stopped directly beneath the edge  34  (corresponding position) of the tool  20 . In this case, the length of the arm bar  33  has to be predefined. 
   The plunger type contact sensor  35  predefines a distance A between the sensor contact face  35 ′ and the edge  34  of the tool  20  at the ending point of the rotation of the arm bar  33 . If the displacement amount of the edge  34  of the tool  20  relative to the sensor contact face  35 ′ is the same as the above-mentioned defined distance during the detection, the plunger type contact sensor  35  senses that it is “normal”. On the other hand, if the displacement amount of the edge  34  of the tool  20  is large, the plunger type contact sensor  35  senses it as “damaged”, and outputs the damaged signal. The output circuit in this case is not illustrated. 
   Next, operation of the device  1  according to this embodiment of the present invention with the direct-acting air driving unit  3  which operates in the vertical or axial direction will be explained. 
   First, air under pressure is supplied from an air compressor or any other suitable source of air under pressure (not shown in the figure) via (for example) a valve or the like. The pressurized air is supplied in the direct-acting air driving unit  3  through the air hose  4  communicated with the pressurized air source (e.g. air compressor). The piston  6  drives the plunger  8  up against the bias of the spring  5 . In an upper movement of the plunger  8 , the rotating cam tube  12  rotates due to the provision of the roller  10  which is supported on the plunger  8 . The rotatable member  14  rotates by this rotation, and the contact bar  18  projecting on the drive shaft  16  rotates via the torque which is applied through the coil spring  15 , and revolves toward the stop-end from the original point. When the contact bar  18  hits the body part of the tool  20  in the middle of the revolution, the contact bar  18  stops. However, the rotatable member  14  still continues to rotate a little further for predetermined rotational angle with the rotating cam tube  12 . 
   As mentioned in the above, when the contact bar  18  contacts the body part of the tool  20  in the middle of the revolution, the device  1  outputs “normal”. When the contact bar  18  passes without contacting the body part of the tool  20 , the device  1  outputs the “damaged” signal by the operation of the magnetic switch  22   a  and the magnet  22   b  provided between the base portion of the sensor drive shaft  16  and the case main body. In addition, in this embodiment of the invention, the magnetic switch is used for the signal output. However, the embodiments of the invention are not limited to the use of this type of magnetic switch, and can take the form of contact switches or the like, provided sufficient waterproofing is provided. Also, in the illustrated embodiments, the contact bar has been shown as rotating clockwise, however, the invention is not so limited and the contact bar can rotate tool counterclockwise if so desired. 
   The embodiments of the invention can be attached to a machine tool such as an automobile, private plane and so on and used as a detection sensor for the damage of the tool or a loss of the edge. Also, since the device  1  of the invention does not use an electric motor, the embodiments of the invention can be used under circumstances wherein a large amounts of cutting agents come in contact with the device and also operate under conditions wherein air is filled with a mist of cutting agents, without difficulty. 
   Although the invention has been described with reference to only a limited number of embodiments the various modifications and variations which are possible without departing from the scope of the present invention, which is limited only the appended claims, will be self-evident to a person of skill in the art to which the present invention pertains or most closely pertains, given the preceding disclosure. 
   The disclosures of Japanese Patent applications No. 2004-32756 filed on Feb. 9, 2004 and No. 2004-347683 filed on Nov. 30, 2004 are incorporated herein.