Patent Application
20150266156
The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2014-58130, filed Mar. 20, 2014. The contents of this application are incorporated herein by reference in their entirety.
The present invention relates to a working head moving device suitable for use in a working apparatus for performing grinding, super-finishing, and so forth on a spherical body.
In the course of the manufacture of spherical products, heretofore it has been customary to adopt a method involving a step of holding a plurality of workpieces (raw spherical bodies) by two parallel grinding plates in sandwich style and a step of effecting relative parallel movement of the two grinding plates to cause the workpieces to roll (to grind the entire spherical surfaces) for increasing the degree of sphericity.
In this regard the present applicants have developed a working apparatus which is highly adaptable to machining on workpieces of varying spherical diameters and is capable of performing grinding, super-finishing, and so forth with greater grinding precision, and already filed a patent application as to this apparatus (refer to Japanese Unexamined Patent Publication JP-A 2012-71413). As shown in
The paired tapered rollers 103 are placed in a uniaxial arrangement, with their smaller-diameter sides opposed to each other, thereby constituting a structure with a V-shaped groove formed at its outer periphery, like a pulley for V-belt. That is, the workpiece W is placed in straddle fashion over the inclined surfaces of the two tapered rollers 103 so as to be retained at its two points. An advantage of this construction is its capacity to handle variations in the spherical diameter of the workpiece W based on the adjustability to the face-to-face distance between the two tapered rollers 103 (the mutual distance in a direction perpendicular to the direction of drilling through the paper sheet with the drawing printed on it).
The paired tapered rollers 103 can be rotatably driven on an individual basis. For example, by rotating the two tapered rollers 103 at the same speed in the same direction, it is possible to allow the workpiece W to rotate regularly about a horizontal axis. On the other hand, with a difference in rotational speed between the two tapered rollers 103, a tilt is imparted to the axis of rotation of the workpiece W. Moreover, by increasing and decreasing the difference in rotational speed between the two tapered rollers 103, it is possible to tilt the axis of rotation of the workpiece W at various angles. Therefore, by continuing such a control to vary the rotational-speed difference, it is possible to impart complex rotary motion to the workpiece W, so that the entire surface (spherical surface) of the workpiece W can pass thoroughly through a location where machining is carried out by the cup-type grinding wheel 104 (contact location). It can thus be said that the two tapered rollers 103 constitute a spheric-rotation driving section 105 for machining (grinding) the entire surface of the workpiece W thoroughly.
In the following specification, the complex rotary motion caused by tilting the axis of rotation of the workpiece W at various angles to perform thorough machining on the entire surface of the workpiece W will be referred to as “spheric rotation”.
In the working apparatus 100, the support 101 serves as an “underside-abutting portion” which supports the workpiece W, and the tapered roller 103 pair serves as a “side-abutting portion” which abuts on the workpiece W to stop its side-to-side movement. That is, the “underside-abutting portion” and the “side-abutting portion” constitute a work setting section 106 for effecting positioning of the workpiece W. Moreover, the pressing roller 102 serves as a “stopper” for retaining the workpiece W to prevent it from being separated from the “side-abutting portion”. It is desirable to add this “stopper” to the construction in the interest of uniqueness and reliability in the positioning of the workpiece W effected by the work setting section 106.
In the working apparatus 100 thusly constructed, when the workpiece W is attached to and detached from the work setting section 106, there is a need to move the cup-type grinding wheel 104 to a retracted position from the machining position. In light of this, for example, a mechanism for moving the cup-type grinding wheel 104 and its rotatably driving section (not shown in the drawings) as well in a direction along the axis of rotation P was adopted (for example, there is known a mechanism for raising and lowering a grinding tool in a vertical direction as disclosed in Japanese Unexamined Patent Publication JP-A 4-135155 (1992).
In the working apparatus 100 of conventional design, the workpiece W supported on the work setting section 106 becomes smaller and smaller (in diameter) as machining (grinding, super-finishing, and so forth) proceeds. At this time, since the workpiece W is subjected to the action of the pressing roller 102, it follows that both the contact with the support 101 serving as the “underside-abutting portion” and the contact with the tapered rollers 103 serving as the “side-abutting portion” are maintained, and a spherical center S moves in a direction N along a bisector drawn between the two contact locations. That is, as slightly exaggerated for purposes of illustration in
In this case, if only the mechanism for allowing movement along the axis of rotation P is adopted for the cup-type grinding wheel 104, a one-sided contact phenomenon, namely a phenomenon in which the cup-type grinding wheel 104 is only partly (only at its left end as viewed in
Meanwhile, with the aim of solving this problem, for example, let it be assumed that there is adopted a mechanism for moving (raising and lowering) the cup-type grinding wheel 104 while rocking it about a position Q established as a pivotal point at some point above the tapered roller 103 as shown in
The present invention has been devised in view of the circumstances as mentioned supra, and accordingly an object of the present invention is to provide a working head moving device adopted in a working apparatus for performing machining such as grinding and super-finishing on a workpiece supported on a work setting section having an underside-abutting portion and a side-abutting portion, the working head moving device being characterized in that it is capable of maintaining proper machining conditions with adaptability to a decrease in size of the workpiece entailed by proceeding of machining process, is capable of performing machining on the workpiece with high degrees of uniformity and precision, and is capable of moving a working head without causing any damage to the workpiece.
In order to accomplish the above object, the present invention takes the following measures.
That is, a working head moving device pursuant to the present invention comprises: a work setting section for effecting positioning of a workpiece by means of an underside-abutting portion which supports a workpiece, and a side-abutting portion which abuts on the workpiece supported on the underside-abutting portion to stop its side-to-side movement; a working head in which a rotary tool is brought into contact with the workpiece positioned by the work setting section, and the rotary tool is driven to rotate about an axis of rotation perpendicular to a workpiece-contacted surface of the rotary tool; and a head moving system for moving the working head between a working-state position for machining the workpiece positioned by the work setting section by the rotary tool and a retracted-state position for separating the working head from the workpiece. The head moving system is provided with a trunnion support portion which allows the working head to rock about an axis of oscillation perpendicular to the axis of rotation when the working head is pressed against the workpiece positioned by the work setting section in conformity with a decrease in size of the workpiece entailed by proceeding of machining process, thereby maintaining an angle of intersection of the workpiece-contacted surface and the axis of rotation invariant.
The workpiece is a spherical body, and it is advisable that the work setting section is provided with a spheric rotation driving section for imparting a rotative force to the workpiece so that the entire spherical surface of the workpiece can be brought into contact with the rotary tool of the working head.
It is preferable that the head moving system comprises: a rocking lever with the working head disposed at its lever front end; and a rocking base part for rockably holding that part of the rocking lever which is spaced away from the lever front end in a lever length direction, and that the trunnion support portion is situated in a junction of the lever front end of the rocking lever and the working head.
It is preferable that the rocking lever is provided with: a driven link disposed so as to protrude radially with respect to the trunnion support portion for rocking movement together with the working head in unitary relation; a base link disposed so as to protrude radially with respect to the rocking base part, for maintaining an angle of protrusion with respect to the rocking base part constant at least before the rocking lever moves the working head to the retracted-state position; and a transmission link for coupling the base link and the driven link so that they become parallel and equal in length, for constituting a parallel link mechanism.
It is preferable that the parallel link mechanism is provided with an operation switching section for allowing switching between enabling and disabling of oscillating movement of the working head relative to the rocking lever.
It is preferable that the rocking lever is coupled with a rocking unit for imparting a rocking force, and the rocking unit is constructed of: a movement driving section for moving the working head between the working-state position and the retracted-state position relative to the workpiece positioned by the work setting section; and a pressurization driving section for pressing the working head in the working-state position against the workpiece, these driving sections being coupled together in a serial arrangement, and that the movement driving section is constructed of an actuator which is operated with a compressible fluid used as an operation source, and the pressurization driving section is constructed of an actuator which is operated with a compressible fluid used as an input source, and with an incompressible fluid used as an operation source.
According to the present invention, the working head moving device adopted in the working apparatus for performing machining such as grinding and super-finishing on a workpiece supported on the work setting section having the underside-abutting portion and the side-abutting portion is capable of maintaining proper machining conditions with adaptability to a decrease in size of the workpiece entailed by proceeding of machining process, is capable of performing machining on the workpiece with high degrees of uniformity and precision, and is capable of moving the working head without causing any damage to the workpiece.
Hereinafter, embodiments of the present invention will be explained with reference to drawings.
As shown in
The work setting section 3 and the working head 4 are substantially the same as those equipped in the working apparatus as disclosed in JP-A 2012-71413, and will thus be described first.
As shown in
The underside-abutting portion 10 may either be of a shoe type for holding the workpiece W for free sliding motion with less friction as shown in
On the other hand, as shown in
Since the face-to-face distance between the tapered rollers 13 can be varied, by making adjustment to the distance, it is possible to handle variations in the spherical diameter of the workpiece W satisfactorily. As employed herein, the term “spherical diameter variations” refers to, in addition to various sized workpieces W as a matter of course, a decrease in size of the workpiece W entailed by proceeding of machining process. Such an adjustability to the face-to-face distance between the tapered rollers 13 is also useful in, when wear occurs in the tapered roller 13, setting the workpiece W in a predetermined position in accordance with the extent of the wear.
These tapered rollers 13 constituting the side-abutting portion 11 also constitute a spheric rotation driving section 16 for permitting spheric rotation of the workpiece W. That is, each of the tapered rollers 13 is rotatably retained via a bearing portion 17, and is connected with a driving portion 18 capable of highly precise control such as a servomotor for individual drive control, and more specifically the tapered rollers 13 can be rotated either in the same direction or in different directions, as well as either at the same speed or at different speeds. Therefore, through the operation of each of the driving portions 18, it is possible to allow the workpiece W to rotate regularly about a horizontal axis by rotating the tapered rollers 13 at the same speed in the same direction, as well as to permit spheric rotation of the workpiece W by causing a difference in rotational speed between the tapered rollers 13.
The working head 4 has a rotary tool 20 such for example as a cup-type grinding wheel (refer to
As shown in
Next, the head moving system 5 will be explained.
The head moving system 5 is a mechanism for holding the working head 4 so as to be movable between a working-state position and a retracted-state position. That is, through the movement of the working head 4 effected by the head moving system 5, the rotary tool 20 can be brought into contact with the workpiece W positioned by the work setting section 3, and at this time pressure can be applied to the workpiece W as required for machining process, and also the rotary tool 20 can be moved away from the workpiece W.
As shown in
The rocking base part 27 is placed in a position midway between the ends of the rocking lever 26 in the direction of the length of the lever. A rocking shaft 45 for holding the rocking lever 26 for free rocking motion relative to the rocking base part 27 is given a sufficiently large thickness. Moreover, a mechanism to support the rocking shaft 45 by a tapered roller bearing 46 is adopted for use in the rocking base part 27. This makes it possible to support the rocking shaft 45 in a thrust direction (axial direction) and a radial direction rigidly with high stability.
The above-described working head 4 is located relative to one end of the rocking lever 26 spaced away from the position to be held by the rocking base part 27 in the lever length direction (right-hand end as viewed in
As shown in
A trunnion support portion 33 is disposed in a junction of the working head 4 and the lever front end 26a of the rocking lever 26. The trunnion support portion 33 is configured so that uniaxially arranged pivot shafts 34 protruding rightward and leftward from the working head 4 can be rotatably supported by bearing portions arranged on the right and left sides of the working head 4 (although not shown in the drawings, the bearing portion is installed in the lever front end 26a of the rocking lever 26). This allows the working head 4 to rock about an axis of oscillation R perpendicular to the rotation axis P of the rotary tool 20.
In the working head 4 which can be freely rocked by the trunnion support portion 33, even with a gradual decrease of the size of the workpiece W positioned by the work setting section 3 entailed by proceeding of machining process, the angle of intersection of the workpiece W-contacted surface of the rotary tool 20 and the rotation axis P of the rotary tool 20 can be maintained invariant. That is, the rotary tool 20 can be kept in pressure-contact with the workpiece W at a constant intersection angle in the course of machining process.
So long as the rotary tool 20 is a cup-type grinding wheel (having an annular bottom end face) and the workpiece W is a spherical body, the intersection angle as mentioned herein invariably stands at 90 degrees, because the rotation axis P of the rotary tool 20 is set so as to pass through the spherical center of the workpiece W. However, the intersection angle is not always 90 degrees, depending on the form of the rotary tool 20 and the shape of the workpiece W (a part to be machined).
As shown in
As shown in
As shown in
The base shaft 42, while being disposed in coaxial relation to the rocking shaft 45 for holding the rocking lever 26 for free rocking motion relative to the rocking base part 27 (uniaxial arrangement), is not coupled to the rocking shaft 45.
The transmission link 39, which is intended to provide coupling between the tip of the driven link 37 (refer to
Meanwhile, as shown in
The brake drive source 49 is intended to move the clamp rod 48 toward and away from the clamp mount 50 by means of a fluid pressure cylinder, an electromagnet, an electric motor, or otherwise. In this structure, as safety measures against troubles such as a power failure, the clamp rod 48 is normally urged in an advancing direction by a spring 52, and the brake plate 47 is pressed against the clamp mount 50 to produce a braking effect (the condition where this braking effect is produced will hereafter be referred to as a “lock condition” of the brake plate 47). In sum, during the time the brake drive source 49 is in a deactivated state, the brake plate 47 is in the lock condition, and, when the brake drive source 49 is set in motion, the lock condition of the brake plate 47 is released.
In the parallel link mechanism 30 designed to include such an operation switching section 40, in the operation switching section 40, when the brake plate 47 is brought into the lock condition by deactivating the brake drive source 49, a lock is applied so that the base shaft 42 and the base link 38 are restrained against relative rotation, with the consequence that the base link 38 maintains the angle of protrusion with respect to the rocking base part 27 constant (unrotatably locked).
That is, as shown in
On the other hand, the working head 4 is held for free oscillating motion to the rocking lever 26 via the trunnion support portion 33, and, the driven link 37 and the working head 4 are coupled together in unitarily rockable relation. Therefore, when the rocking lever 26 is rocked up and down while defining a rocking path L1 in the form of an arc about the rocking shaft 45 acting as a pivotal point to move the working head 4 upward and contrarily downward, then the base link 38 and the driven link 37 are kept in parallel with each other, and the angular relation between the driven link 37 and the working head 4 is maintained invariant. That is, the rotary tool 20 of the working head 4 moves up and down while defining a rocking path L2 having the same radius of curvature as that of the arcuate rocking path L1 defined by the rocking lever 26, and, its separation from the workpiece W (upward movement) and contact with the workpiece W (downward movement) are effected in accordance with this rocking path L2.
Such an arcuate rocking path is obviously different from the retracting path (in the form of a downwardly convex arc) of the cup-type grinding wheel 104, which has already been described with reference to
On the other hand, in the operation switching section 40, by actuating the brake drive source 49 to release the lock condition of the brake plate 47, the clamp rod 48 is returned to its retracted state against the action of the spring 52, thereby permitting free relative rotation of the base shaft 42 and the base link 38. That is, the base link 38 is held for free rocking motion to the rocking base part 27.
Accordingly, although the rocking lever 26 is non-rockably at rest, the working head 4 is kept in an oscillatable state by the trunnion support portion 33, wherefore the following advantageous effect afforded by the trunnion support portion 33 can be attained: the angle of intersection of the workpiece W-contacted surface of the rotary tool 20 and the rotation axis P of the rotary tool 20 can be maintained invariant even when the workpiece W positioned by the work setting section 3 becomes smaller and smaller (in diameter) as machining process proceeds.
Thus, switching between enabling and disabling of the oscillating movement of the working head 4 relative to the rocking lever 26 can be done by making selection between deactivation and activation of the brake drive source 49 of the operation switching section 40. When it is desired to retract (raise) the rotary tool 20 of the working head 4 to separate it from the workpiece W positioned by the work setting section 3, the brake drive source 49 has to be deactivated to bring the brake plate 47 into the lock condition without fail.
As shown in
The rocking unit 28 is constructed by coupling a movement driving section 53 and a pressurization driving section 54 in a serial arrangement. As employed herein, the term “serial arrangement” refers to an arrangement of both driving sections 53 and 54 such that a driving force exerted by the movement driving section 53 and a driving force exerted by the pressurization driving section 54 are presented in a mutually-connected array form. Accordingly, a plurality of arrangement forms will be considered, i.e. an arrangement wherein the movement driving section 53 and the pressurization driving section 54 are coupled to each other at their tail sides; an arrangement wherein the movement driving section 53 and the pressurization driving section 54 are coupled to each other at their driving sides; and an arrangement wherein the movement driving section 53 and the pressurization driving section 54 are so placed that the tail side of one of them is coupled to the driving side of the other.
It is noted that the arrangement such that a driving force exerted by the movement driving section 53 and a driving force exerted by the pressurization driving section 54 are presented in coaxial relation (uniaxial arrangement) is not a requirement, wherefore an arrangement with some axial deviation is permissible. Accordingly, for example, it is possible to adopt an arrangement such that a plurality of the movement driving sections 53 or the pressurization driving sections 54, or a plurality of both the movement driving sections 53 and the pressurization driving sections 54, are placed in parallel. The movement driving section 53 is constructed of an actuator which is operated with a compressible fluid (air or other gas) used as an operation source. For example, an air cylinder is used for the movement driving section 53. The movement driving section 53 is connected, at its drive control system, to an electromagnetic valve 55, and is also connected to an electropneumatic regulator 56 capable of controlling compressible-fluid supply pressure arbitrarily in proportion to electric signals.
The pressurization driving section 54 is constructed of an actuator which is operated with a compressible fluid (air or other gas) used as an input source, and with an incompressible fluid (water or oil) used as an operation source. For example, an air-hydro cylinder is used for the pressurization driving section 54. The pressurization driving section 54, utilizing a compressible fluid as its input source, is also connected, at its drive control system, to the electromagnetic valve 55 and the electropneumatic regulator 56. In addition, an air-hydro converter 57 is connected to the pressurization driving section 54 which utilizes both a compressible fluid and an incompressible fluid.
In the rocking unit 28 comprising the movement driving section 53 and the pressurization driving section 54, a driving force exerted by the movement driving section 53 is utilized to move the working head 4 between the working-state position and the retracted-state position relative to the workpiece W positioned by the work setting section 3. This makes it possible to accomplish high-speed working head 4 movement, and thereby attain the advantage of shortening an operation cycle.
On the other hand, a driving force exerted by the pressurization driving section 54, or equivalently a pressing force derived from an incompressible fluid, is utilized to press (apply pressure to) the working head 4 in contact with the workpiece W against the workpiece W for machining process. This makes it possible to ensure stable positioning of the working head 4 (rotary tool 20), and thereby attain the advantage of preventing occurrence of machining vibration (chattering), for example. Moreover, the pressurization driving section 54 brings the rotary tool 20 into proper alignment with the workpiece W with a high degree of precision in accordance with the extent of wear in the rotary tool 20. Furthermore, even with the progression of wear in the rotary tool 20 or a decrease in size of the workpiece W entailed by proceeding of machining process, highly accurate following movement can be imparted to the working head 4.
In the rocking unit 28, since the electropneumatic regulator 56 is adopted for each of the movement driving section 53 and the pressurization driving section 54, it is possible to exercise control in a manner such that the driving sections 53 and 54 are subjected to the same supply pressure, and that the supply pressure for one of the driving sections 53 and 54 is slightly higher than that for the other (for example, the supply pressure for the movement driving section 53 is slightly higher than that for the pressurization driving section 54). Therefore, when a load is abruptly applied to the working head 4 in a direction in which it is pressed back by the workpiece W, a damper effect to absorb the load can be obtained from the movement driving section 53. This makes it possible to, for example, move the working head 4 so as to conform to roughness (major irregularities) of the workpiece W in the early stages of machining process, and thereby avoid damage such as a surface flaw to the workpiece W. As another advantage, the working head 4 (rotary tool 20, in particular) can be protected from breakage.
In this embodiment, in the interest of ease in changing of the workpiece W, replacement of the rotary tool 20, and various maintenance operations for the working head 4 and so forth, as shown in
Therefore, as shown in
In this way, changing of the workpiece W can be effected by means of a handling device or otherwise, which is so conducive to energy saving, automation, highly-efficient operation, and so forth.
As is apparent from the foregoing detailed description, in the working head moving device 1 pursuant to the present invention, the workpiece W supported on the work setting section 3 becomes smaller and smaller, while being kept in contact with the underside-abutting portion 10 and the side-abutting portion 11, as machining process proceeds, and, even if a spherical center S (refer to
Moreover, since the working head 4 is moved by the rocking lever 26 provided with the parallel link mechanism 30, it never occurs that the rotary tool 20 interferes with the workpiece W during the retracting movement, wherefore there is no risk of occurrence of a flaw in the workpiece W posed as a problem associated with the conventional art (refer to
As described heretofore, it is possible to maintain proper machining conditions with adaptability to a decrease in size of the workpiece W entailed by proceeding of machining process, and thereby perform machining on the workpiece W with high degrees of uniformity and precision. Moreover, the working head can be moved without causing any damage to the workpiece W.
It should be understood that the present invention is not limited to the embodiments described hereinabove, and therefore various changes and modifications can be made on the basis of the embodiments.
For example, the rotary tool 20 of the working head 4 is not limited to a cup-type grinding wheel, but may be of another component such as grinding wheels of various shapes, for example, a columnar grinding wheel, a grinding wheel shaped like a frustum of a cone, and a ball-like grinding wheel, or a cutting tool such as an end mill.
Although the work setting section 3 is illustrated as being so designed that the paired tapered rollers 13 do double duty; that is, serve as both the side-abutting portion 11 and the spheric rotation driving section 16, this does not suggest any limitation. The side-abutting portion 11 and the spheric rotation driving section 16 can be provided independently of each other. Moreover, the form of each of the underside-abutting portion 10 and the side-abutting portion 11 can be altered as required in accordance with the shape of the workpiece W, and also, the structure of contact between each of the portions 10 and 11 and the workpiece W can be altered.
Although the head moving system 5 is illustrated as having the parallel link mechanism 30, this does not suggest any limitation. For example, a four-link mechanism such as a trapezoidal link (the driven link 37, the base link 38, and the transmission link 39 are designed to have different lengths) can be adopted instead of the parallel link mechanism 30.
The workpiece W is not limited to a spherical body, and therefore, for example, a disk-shaped workpiece, a polyhedron-shaped workpiece, and a prismatic block-shaped workpiece can be a target workpiece.
It is to be understood that although the present invention has been described with regard to preferred embodiments thereof, various other embodiments and variants may occur to those skilled in the art, which are within the scope and spirit of the invention, and such other embodiments and variants are intended to be covered by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-58130 | Mar 2014 | JP | national |
