Abstract: A synthetic grinding stone used for the polishing of a silicon wafer is composed of a structure containing cerium oxide fine particles as abrasive grains, a resin as a binder, a salt as a filler and a nano diamond as an additive. This synthetic grinding stone is characterized in that the purity of the cerium oxide is not less than 60% by weight, the content of the salt as a filler is not less than 1% but not more than 20%, the volume content of the nano diamond as an additive is not less than 0.1% but less than 20% relative to the total volume of the structure, and the porosity as the volume fraction relative to the total volume of the structure is less than 30%.

Abstract: A precision machining method enabling grinding with high accuracy is provided. The method includes a first step of producing an intermediate ground workpiece by roughly grinding a workpiece (a) with a diamond grinding wheel (b), and a second step of producing a final ground workpiece by grinding the intermediate ground workpiece with a grinding wheel for CMG. In the first step, feed of the rotator (6b) and the base (3) is controlled in multiple stages with different feed speeds according to control based on the amount of movement, and in the second step, movement of the rotator (6b) and the base (3) is controlled with a constant pressure or in multiple stages having different constant pressures.

Abstract: A precision machining apparatus is structured such that a feed-screw mechanism and an actuator are mounted on a second mount which supports a rotating device that rotates a wheel, and grinding is performed while appropriately adjusting the amount of movement of the second mount in a rough grinding stage through an ultra-precision grinding stage. A posture control device is interposed between a first mount and a rotating device that rotates a grinding target body. The thickness and evenness of the grinding target body are measured by an optical probe and the measurement results are sent to a computer. A feedback command is then sent to the posture control device to reduce the difference between target values and the measurement values and posture control is performed accordingly.

Abstract: A precision machining apparatus is structured such that a feed-screw mechanism and an actuator are mounted on a second mount which supports a rotating device that rotates a wheel, and grinding is performed while appropriately adjusting the amount of movement of the second mount in a rough grinding stage through an ultra-precision grinding stage. A posture control device is interposed between a first mount and a rotating device that rotates a grinding target body. The thickness and evenness of the grinding target body are measured by an optical probe and the measurement results are sent to a computer. A feedback command is then sent to the posture control device to reduce the difference between target values and the measurement values and posture control is performed accordingly.

Abstract: Disclosed is a synthetic grinding stone used for polishing of silicon wafer, which is composed of a structure comprising cerium oxide fine particles as abrasive grain, a resin as a binder, a salt as a filler and a nano diamond as an additive. This synthetic grinding stone is characterized in that the purity of the cerium oxide is not less than 60% by weight, the content of the salt as a filler is not less than 1% but not more than 20%, the volume content of the nano diamond as an additive is not less than 0.1% but less than 20% relative to the total volume of the structure, and the porosity as the volume fraction relative to the total volume of the structure is less than 30%.

Abstract: In an electric power steering device, the performances of a reduction unit and a rack unit are easily warranted independently of each other, the reduction unit and the rack unit are simply assembled, the degree of freedom for the fastened positions of the reduction unit and a rack housing are raised, and advantage of the layout are taken.

Abstract: A precision machining method enabling grinding with high accuracy is provided. The method includes a first step of producing an intermediate ground workpiece by roughly grinding a workpiece (a) with a diamond grinding wheel (b), and a second step of producing a final ground workpiece by grinding the intermediate ground workpiece with a grinding wheel for CMG. In the first step, feed of the rotator (6b) and the base (3) is controlled in multiple stages with different feed speeds according to control based on the amount of movement, and in the second step, movement of the rotator (6b) and the base (3) is controlled with a constant pressure or in multiple stages having different constant pressures.

Abstract: An electrically driven power steering apparatus is structured such that a large impact on a rack shaft occurs upon an impingement of a steering stopper, and, even when an axial force acting on a ball bearing of a presser member becomes zero, a rotation of the presser member is hindered by caulking c at a thin plate member. Therefore, the presser member does not slacken, and a predetermined axial force can be given again to the ball bearing when the impact dissipates. The thus structured power steering apparatus exhibiting, though the cost is low, an excellent shockproof characteristic and capable of preventing the bearing from coming off a ball screw nut, can be provided.

Abstract: Male splines 21 and 23 formed in both the end parts of a torsion bar 5 are fitted and fixed to female splines 22 and 24 formed in an input shaft 2 and an output shaft 3. Further, the number of irregularities of protruding and recessed shaped stoppers 18 and 19 is the same as the number of irregularities of the male splines 21 and 23 formed on the torsion bar 5. The male splines 21 and 23 of both the end parts of the torsion bar 5 have the same phase. Accordingly, even when the torsion bar 5 and both the shafts 2 and 3 are attached to any phase, an angle regulated by the stoppers 18 and 19 when both the shafts 2 and 3 are distorted is substantially the same angle in right and left with respect to a neutral position.

Abstract: An electric power steering apparatus comprises a rotary shaft member connected to a steering wheel, an elongate member, a rack-and-pinion mechanism, a ball screw mechanism constructed of a screw member, a nut member and a multiplicity of balls interposed between the screw member and the nut member, an electric motor unit, and a meshing type rotation decelerating mechanism including a plurality of meshing components. The meshing components include an output shaft pinion gear, a deceleration gear, and an intermediate gear, interposed between the output shaft pinion gear and the deceleration gear, having a contact portion composed of a synthetic resin.

Abstract: An electrically driven power steering apparatus is structured such that a large impact on a rack shaft occurs upon an impingement of a steering stopper, and, even when an axial force acting on a ball bearing of a presser member becomes zero, a rotation of the presser member is hindered by caulking c at a thin plate member. Therefore, the presser member does not slacken, and a predetermined axial force can be given again to the ball bearing when the impact dissipates. The thus structured power steering apparatus exhibiting, though the cost is low, an excellent shockproof characteristic and capable of preventing the bearing from coming off a ball screw nut, can be provided.

Abstract: In an electric power steering apparatus in which steering torque applied on a steering wheel is detected by a torque sensor, and a steering assist torque is generated by an electric motor in accordance with the detected steering torque and transmitted to an output shaft of a steering mechanism with a speed reduced by a worm gear mechanism, the gear meshing position in the worm gear mechanism and the position of the torque sensor are arranged to be substantially coincide with each other with respect to the axial direction of the output shaft. Alternatively, a worm wheel of the worm gear mechanism is directly supported on a housing in a rotatable manner by means of a bearing. A steering shaft and an input shaft of a power assist section are fixedly connected in close contact attained by plastic deformation.

Abstract: A precision machining apparatus and a precision machining method capable of carrying out grinding with accuracy by performing switching control, for example, on a device for rotating a grinding wheel according to grinding stages through the amount of movement and constant pressure changed stepwise. To a second pedestal 3 supporting a rotary device 6b for rotating a grinding wheel b, an actuator 5 and a feed screw mechanism 4 constituted by at least a feed screw 41 and a nut 42 are attached. In a rough grinding stage, the movement of the rotary device 6b and the second pedestal 3 is adjusted through a predetermined amount of movement of the nut 42. In a super-precision grinding stage, the movement of the rotary device 6b and the second pedestal 3 is adjusted by pressure control using stepwise a plurality of pneumatic actuators 5a, 5b differing in pressure performance. An attitude control device 7 is interposed between a first pedestal 2 and a rotary device 6a for rotating an object a to be ground.

Abstract: An electric power steering apparatus comprises a ball nut rotationally driven by an electric motor through a gear train and having a female thread groove formed in the inner periphery thereof, a rack shaft disposed through the ball nut on the axis thereof and having a male thread groove so formed in its outer periphery as to face to the female thread groove, a ball screw mechanism having a number of circulation balls interposed between the female thread groove and the male thread groove, and a housing for holding the ball nut rotatably through the bearing. An elastic member is interposed between the housing and the ball nut in order to permit the ball nut to make a predetermined displacement.

Abstract: An electrically driven power steering apparatus is structured such that a large impact on a rack shaft (22) occurs upon an impingement of a steering stopper, and, even when an axial force acting on a ball bearing (25) of a presser member (30) becomes zero, a rotation of the presser member (30) is hindered by caulking c at a thin plate member (30b). Therefore, the presser member (30) does not slacken, and a predetermined axial force can be given again to the ball bearing (25) when the impact dissipates. The thus structured power steering apparatus exhibiting, though the cost is low, an excellent shockproof characteristic and capable of preventing the bearing from coming off a ball screw nut, can be provided.

Abstract: An electrically driven power steering apparatus is structured such that a large impact on a rack shaft occurs upon an impingement of a steering stopper, and, even when an axial force acting on a ball bearing of a presser member becomes zero, a rotation of the presser member is hindered by caulking c at a thin plate member. Therefore, the presser member does not slacken, and a predetermined axial force can be given again to the ball bearing when the impact dissipates. The thus structured power steering apparatus exhibiting, though the cost is low, an excellent shockproof characteristic and capable of preventing the bearing from coming off a ball screw nut, can be provided.

Abstract: Provided is an electric power steering apparatus comprising a housing, a motor attached to this housing and transmitting an auxiliary steering force to a rotary shaft through a motor shaft, a worm formed on or fitted on the rotary shaft and having a gear portion formed of a metal or a resin, rolling bearings provided in the housing, disposed respectively in positions on both sides of the worm and rotatably supporting the rotary shaft, an output shaft transmitting a steering force for steering an axle and rotatably supported in a predetermined position of the housing, and a worm wheel formed on or fitted on the output shaft in a way that meshes with the worm and having a gear portion formed of the resin, wherein a pre-load mechanism for applying a pre-load acting towards the worm wheel is provided at a shaft end portion, distal from the motor, of the rotary shaft.

Abstract: In an electric power steering apparatus that generates an auxiliary steering torque by a brushless motor in response to a steering torque applied on a steering wheel and transmits it to an output shaft of a steering mechanism while reducing it by means of a reduction gear, the apparatus comprises a rotor (10) to which a cylindrical permanent magnet for rotational driving (12) and a member to be detected (13) for detection of a rotational angle of the rotor are attached and a cylindrical stator (30) opposed to the rotor in which a laminated core (16) on which a coil is wound, detection means (17) for detecting the rotational angle of the rotor by the member to be detected and a terminal (19) for providing connection to the coil are integrally formed by resin molding. At least one bearing (8, 9) for rotatably supporting the rotor is disposed radially inside the stator and between the permanent magnet for rotational driving and the member to be detected.

Abstract: An attitude control device and a precision machining apparatus capable of accurately controlling the attitude of an object mounted on the attitude control device according to grinding stages. The attitude control device is constituted by a first flat-plate member 21 and a second flat-plate member 22 disposed in parallel with the first flat-plate while being spaced apart from the same by a distance L. A spherical member 3 is interposed between the first and second flat-plate members 21, 22 while fitting its portions in recesses 21a, 22a respectively formed in the first and second flat-plate members 21, 22. A first actuator 4a expandable in a Z-axis direction perpendicular to a plane defined by an X-axis and a Y-axis is interposed between the flat-plate members. Second actuators 4b, 4b expandable in a suitable direction in the plane defined by the X-axis and the Y-axis are connected to the second flat-plate member 22.

Abstract: An attitude control device and a precision machining apparatus capable of accurately controlling the attitude of an object mounted on the attitude control device according to grinding stages. The attitude control device is constituted by a first flat-plate member 21 and a second flat-plate member 22 disposed in parallel with the first flat-plate while being spaced apart from the same by a distance L. A spherical member 3 is interposed between the first and second flat-plate members 21, 22 while fitting its portions in recesses 21a, 22a respectively formed in the first and second flat-plate members 21, 22. A first actuator 4a expandable in a Z-axis direction perpendicular to a plane defined by an X-axis and a Y-axis is interposed between the flat-plate members. Second actuators 4b, 4b expandable in a suitable direction in the plane defined by the X-axis and the Y-axis are connected to the second flat-plate member 22.