JP2013215822A - Centerless grinding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centerless grinding device preventing scratch damage generated in an outer peripheral surface of a workpiece due to grinding particles falling down from the surface of a grinding stone and the outer peripheral surface of the workpiece sliding on the supporting surface of a blade.SOLUTION: A centerless grinding device 100 grinding the outer periphery of a charged workpiece 10 has a blade 50 supporting the workpiece 10 from under the same, a grinding stone 20 grinding workpiece 10, and an adjusting wheel 30 located in an oblique opposite side sandwitching the blade 50 viewing from the grinding stone 20. A cutout part 53 extending in a right and left direction is arranged in the supporting surface 51 of the blade 50. Grinding particles falling down from the outer peripheral surface 21 of the grinding stone 20 when the grinding stone 20 grinds the workpiece 10 enter into the cutout part 53 therefore the sliding of the grinding particles and the outer peripheral surface 11 of the workpiece 10 is not generated. Consequently, scratch damage generated in the outer peripheral surface 11 of the workpiece 10 by the sliding with the grinding particles can be prevented.

Description

  The present invention relates to a centerless grinding apparatus for grinding a workpiece by centerless grinding.

  2. Description of the Related Art Conventionally, a glow plug for an automobile uses a round bar-shaped ceramic heater that has a built-in heating element that generates heat when energized and has a tapered end. Such a ceramic heater is formed by sandwiching a heating element and an electrode in a plate-like substrate made of an insulating ceramic having excellent corrosion resistance, pressing the entire body to form it integrally, and after removing the binder from the molded body, firing it. Is done.

  In many cases, a plurality of ceramic heaters are connected side by side until firing, and this is divided into individual ceramic heaters after firing to form a cylindrical ceramic heater. Thereafter, the ceramic heater is set as a workpiece in a centerless grinding apparatus, the ceramic heater is subjected to centerless grinding, and a tip is provided with a taper.

  A conventional centerless grinding apparatus includes a grinding wheel that is rotatably provided, an adjustment wheel that is disposed opposite to the grinding wheel to adjust the position and rotation speed of a workpiece to be ground, and a gap between the two. It has a structure provided with a blade that supports a workpiece from below during grinding. The workpiece whose rotation is adjusted by the adjusting wheel comes into contact with a grinding wheel rotating at a rotation speed different from that of the workpiece, whereby the workpiece is ground. Here, abrasive grains that fall off from the surface of the grinding wheel during grinding enter between the support surface of the blade and the workpiece, and the abrasive grains and the workpiece slide to cause scratches on the surface of the workpiece. There was a problem.

  In order to solve this problem, a grinding apparatus has been proposed in which a blade is a rotatable cylindrical body or columnar body whose own axial direction is substantially parallel to the workpiece axial direction (see, for example, Patent Document 1). In the invention disclosed in Patent Document 1, the blade follows as the workpiece to be ground rotates. For this reason, even if abrasive grains enter between the blade and the workpiece, the sliding frictional force between the abrasive grains and the workpiece is reduced, and the generation of scratches is suppressed. In addition, a grinding wheel having a saw blade shape in which the apex portion is chamfered on the support surface of the blade has been proposed (for example, see Patent Document 2). In the invention disclosed in Patent Document 2, the blade and the workpiece do not contact except at the apex portion. For this reason, the abrasive grains entering between the support surface of the blade and the workpiece do not remain on the support surface, and the generation of scratches is suppressed.

JP-A-9-239648 JP-A-9-239649

  However, in the inventions disclosed in Patent Document 1 and Patent Document 2, since it is impossible to eliminate the sliding itself between the abrasive grains and the workpiece, it is substantially impossible to prevent the above scratches. There was a problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a centerless grinding apparatus that does not cause scratches on the outer periphery of a workpiece in a grinding step of providing a taper on the workpiece.

  According to the centerless grinding apparatus of one aspect of the present invention, the centerless grinding apparatus grinds the outer periphery of the workpiece, and the grinding wheel that grinds the outer periphery of the workpiece and the opposite side of the grinding stone as viewed from the grinding wheel. An adjustment wheel that is disposed on the side and applies thrust to the workpiece toward the grinding wheel side, and is disposed in a gap between the grinding wheel and the adjustment wheel, supports the workpiece, and is an end face that faces the workpiece. There is provided a centerless grinding apparatus provided with a blade having a notch portion extending along a longitudinal direction of the workpiece and allowing abrasive grains falling off the surface of the grinding wheel to escape.

  In this aspect, the abrasive grains falling from the surface of the grinding wheel by grinding enter the notch portion of the blade, so that the sliding between the abrasive grains and the work is suppressed, and scratches generated on the outer periphery of the work can be prevented. it can.

  In the longitudinal direction of the workpiece, the length of the notch may be equal to or less than half the length of the workpiece. Thereby, since half or more of the full length of a workpiece | work is supported by a braid | blade in a workpiece | work longitudinal direction, a braid | blade can support a workpiece | work stably.

  In the cutout portion, the depth recessed in the direction away from the workpiece may be greater than or equal to the grain size of the abrasive grains. As a result, the abrasive grains can completely enter the notch, and contact between the abrasive grains and the workpiece can be prevented, and scratches generated on the outer periphery of the workpiece can be prevented.

  The blade may be separated from the work in a range where the notch is provided. Accordingly, the abrasive grains do not slide with the blade in the range where the notch is provided, and the scratches generated on the outer periphery of the workpiece can be reliably prevented.

  A corner of the end surface on the cutout side may be chamfered. Thereby, even if the workpiece may move in the longitudinal direction of the blade, the workpiece can be stably moved without being caught by the corner of the notch.

1 is a perspective view of a centerless grinding apparatus 100 on which a workpiece 10 is set. FIG. 3 is a perspective view of a blade 50 that supports a workpiece 10. 2 is a right side view of the centerless grinding apparatus 100. FIG. 1 is a plan view of a centerless grinding apparatus 100. FIG. 7 is a perspective view showing a state where the stopper 70 is lowered to the lower end position in the grinding process of the workpiece 10. FIG. 3 is a partially enlarged view of a notch 53 when grinding a workpiece 10. FIG.

  Hereinafter, an embodiment of a centerless grinding apparatus embodying the present invention will be described with reference to the drawings. With reference to FIG. 1, the whole structure of the centerless grinding apparatus 100 as an example is demonstrated. The drawings to be referred to are used for explaining the technical features that can be adopted by the present invention, and the configuration and the like of the centerless grinding apparatus described are not intended to be limited to this, but are merely illustrative examples. It is. In the present embodiment, the right side, left side, upper side, lower side, upper left side, and lower right side of FIG. 1 are defined as the right side, left side, upper side, lower side, back side, and front side of the centerless grinding apparatus 100, respectively. This will be described below.

  The centerless grinding apparatus 100 of the present embodiment is configured to provide a taper on the outer peripheral surface 11 of a round bar-shaped ceramic heater used for a glow plug (not shown) as a workpiece 10 in the manufacturing process. Specifically, the centerless grinding apparatus 100 grinds the outer peripheral surface 11 of the workpiece 10 that has been processed into a cylindrical shape in the previous step over a predetermined range, and provides a taper. A centerless grinding apparatus 100 shown in FIG. 1 includes a blade 50 that supports a workpiece 10, a grinding wheel 20 that grinds the workpiece 10, an adjustment wheel 30 that is diagonally opposite to the blade 50 when viewed from the grinding wheel 20, and an adjustment. The presser roller 60 which opposes on both sides of the vehicle 30 and the blade 50 is provided.

  First, the blade 50 will be described. The blade 50 is disposed on a bed (not shown) provided in the centerless grinding apparatus 100. As shown in FIGS. 1 and 2, the blade 50 has a plate shape having a predetermined thickness, and a planar support surface 51 that is an upper surface extends in the left-right direction. The support surface 51 supports the workpiece 10 from below. A part of the support surface 51 is provided with a notch 53 that is recessed downward from the support surface 51 and extends in the left-right direction. The left end surface 55 of the notch 53 is located on the right side of the left end surface of the blade 50. Further, the right end surface 54 and the left end surface 55 of the notch 53 are substantially parallel to each other. Here, the length in the left-right direction of the notch 53 is configured to be ½ or less of the length in the left-right direction of the workpiece 10, and the depth of the notch 53 constitutes the grinding wheel 20 described later. It is comprised so that it may become more than the maximum particle size of the abrasive grain 23 to do. In the present embodiment, as an example, the maximum grain size of the abrasive grains 23 is about 0.1 mm, the length of the notch 53 is 10 mm, and the depth is 0.2 mm. Thereby, even if the abrasive grains 23 fall off from the outer peripheral surface 21 of the grinding wheel 20 described later, the abrasive grains 23 can completely enter the notch 53. Further, a corner 52 of the support surface 51 on the side of the notch 53 is chamfered. In addition, the depth of the notch part 53 shown in FIGS. 1-3, FIG. 5, and FIG. 6 is deeply illustrated from the actual thing for the sake of visibility of drawing.

  As shown in FIG. 1, a substantially rectangular parallelepiped stopper 70 is provided on the left side of the blade 50. The stopper 70 includes a rectangular parallelepiped column 73 extending in the vertical direction and a protrusion 71 provided on the right end surface of the column 73. The protrusion 71 protrudes substantially horizontally toward the right side on the upper side of the right end surface of the column 73, and the right end portion is formed in a hemispherical shape. The stopper 70 can be lifted up and down by lifting means (not shown). Specifically, the stopper 70 has a substantially same height from the lower end position (see FIG. 5) where the upper surface 72 and the support surface 51 of the blade 50 are substantially the same height. It can be moved up and down to the upper end position (see FIG. 1). At the time of grinding, the stopper 70 is at the upper end position, and after the grinding is finished, the stopper 70 is lowered to the lower end position.

  As shown in FIGS. 1 and 3, a cylindrical grinding wheel 20 in which superabrasive grains such as diamond are held by a binder is supported by a shaft 22. The radius of the circular end surface forming the left and right ends of the grinding wheel 20 is larger than the length of the grinding wheel 20 in the axial direction (the height of the cylinder). Further, the axis of the grinding wheel 20 is on the near side and below the support surface 51. As shown in FIG. 4, the grinding wheel 20 is inclined in a direction away from the blade 50 as its axis 24 moves to the right side. As a result, when viewed in a plan view, in the ridge line 21A forming the end of the outer peripheral surface 21 of the grinding wheel 20 on the blade 50 side, the right side is not in contact with the outer peripheral surface 11 of the workpiece 10, and the left side is the workpiece It is comprised so that the outer peripheral surface 11 of 10 may be contacted. In FIG. 3, the grinding wheel 20 with its own axis 24 parallel to the longitudinal direction of the blade 50 is shown for the sake of easy viewing. The grinding wheel 20 is rotated at a constant speed by a driving means (not shown) clockwise (in the direction of arrow A in FIG. 3) when viewed from the right side. At the time of grinding, the outer peripheral surface 21 of the grinding wheel 20 and the outer peripheral surface 11 of the work 10 come into contact with each other, and the outer peripheral surface 11 of the work 10 is ground.

  As shown in FIGS. 1 and 3, the cylindrical adjustment wheel 30 is arranged on the opposite side and the right side of the grinding wheel 20 with the blade 50 interposed therebetween. The adjustment wheel 30 is supported by a shaft 32. The radius of the circular end surface forming the left and right ends of the adjustment wheel 30 is larger than the length of the adjustment wheel 30 in the axial direction (the height of the cylinder). Further, the axis of the adjustment wheel 30 is on the rear side and the lower side of the support surface 51, and the radius is smaller than that of the grinding wheel 20. The outer peripheral surface 31 of the adjusting wheel 30 has a grip force larger than that of the outer peripheral surface 21 of the grinding wheel 20 in order to brake the rotation of the workpiece 10 during grinding. Further, as shown in FIG. 4, the axis 34 of the adjustment wheel 30 is substantially parallel to the longitudinal direction of the blade 50. Further, as shown in FIG. 1, the adjustment wheel 30 is inclined in a direction in which the left end surface faces slightly downward. In FIGS. 3 and 4, for the sake of easy viewing of the drawings, the adjustment wheel 30 that is not inclined is illustrated. The adjustment wheel 30 is rotated at a constant speed by a driving means (not shown) clockwise (in the direction of arrow B in FIG. 3) when viewed from the right side. The rotational speed of the outer peripheral surface 31 of the adjusting wheel 30 during rotation is adjusted to be slower than the rotational speed of the outer peripheral surface 21 of the grinding wheel 20.

  As shown in FIGS. 1 and 3, the cylindrical presser roller 60 is provided at a position on the right side of the grinding wheel 20 and at a position facing the adjustment wheel 30 and the blade 50. The presser roller 60 is rotatably supported on a shaft 62. Further, the radius of the circular end surface forming the left and right ends of the presser roller 60 is larger than the length of the presser roller 60 in the axial direction (the height of the cylinder). The axis of the presser roller 60 is on the front side and the upper side of the axis of the workpiece 10 to be ground, and the radius is smaller than that of the grinding wheel 20 and the adjusting wheel 30. As shown in FIG. 4, the axis 64 of the presser roller 60 is substantially parallel to the longitudinal direction of the blade 50. Furthermore, as shown in FIG. 3, the presser roller 60 is configured to press the outer peripheral surface 11 of the workpiece 10 to be ground from the front side and the upper side by pressing means not shown. Note that the presser roller 60 is configured to retract to a retracted position that is further on the upper side than the pressing position that presses the outer peripheral surface 11 when the workpiece 10 is supplied. In other words, the presser roller 60 is configured to descend from the retracted position to the pressing position after the workpiece 10 is supplied, and press the outer peripheral surface 11 of the workpiece 10 obliquely from above by pressing means (not shown).

  Next, operation | movement of the centerless grinding apparatus 100 of this Embodiment is demonstrated. The workpiece 10 processed into a columnar shape in the previous step is loaded to a position where the left end surface of the workpiece 10 is on the same plane as the left end surface of the blade 50 by unillustrated loading means. At this time, the stopper 70 is raised to the upper end position by a lifting / lowering means (not shown), so that the axis of the projection 71 and the axis of the workpiece 10 have substantially the same height. Further, the pushing means (not shown) pushes the right end surface of the workpiece 10 to the left, so that the left end surface of the workpiece 10 comes into contact with the right end portion of the protrusion 71. Thereby, the workpiece 10 is positioned in the left-right direction. The workpiece 10 is set in a state where the axis thereof is substantially parallel to the longitudinal direction of the blade 50, and the outer peripheral surface 11 is in contact with the outer peripheral surface 21 of the grinding wheel 20 and the outer peripheral surface 31 of the adjustment wheel 30. Thereafter, the pressing roller 60 is lowered from the retracted position to the pressing position, and the outer peripheral surface 61 of the pressing roller 60 presses the outer peripheral surface 11 of the workpiece 10 by the pressing means (see FIG. 1). Further thereafter, the grinding wheel 20 starts rotating clockwise (in the direction of arrow A in FIG. 3) when viewed from the right side. The adjustment wheel 30 also starts to rotate clockwise as viewed from the right side.

  The outer peripheral surface 61 of the presser roller 60 presses the outer peripheral surface 11 of the work 10 against the outer peripheral surface 31 of the adjustment wheel 30, so that the work 10 is forcibly rotated by the rotation of the adjustment wheel 30. Further, as the work 10 rotates, the presser roller 60 is also driven. The workpiece 10 does not spring up from the support surface 51 of the blade 50 due to the pressing of the presser roller 60, and the outer peripheral surface 11 of the workpiece 10 is continuously in contact with the outer peripheral surface 31 of the adjustment wheel 30. Further, as described above, the adjustment wheel 30 is inclined in the direction in which the left end surface faces slightly downward, so that the workpiece 10 obtains thrust toward the left side by the rotation of the adjustment wheel 30, and its left end surface. Continues to contact the right end of the protrusion 71 of the stopper 70. As a result, the left end portion of the workpiece 10 continues to contact the grinding wheel 20 that rotates at a predetermined rotation speed.

  Here, a process in which the outer peripheral surface 11 of the workpiece 10 is ground to the outer peripheral surface 21 of the grinding wheel 20 will be described. As described above, the outer peripheral surface 21 of the grinding wheel 20 rotates at a faster rotational speed than the outer peripheral surface 31 of the adjustment wheel 30. On the other hand, the outer peripheral surface 31 of the adjusting wheel 30 has a larger gripping force than the outer peripheral surface 21 of the grinding wheel 20, and the outer peripheral surface 11 of the workpiece 10 rotates at the same rotational speed as the outer peripheral surface 31 of the adjusting wheel 30. Try to do. Therefore, the outer peripheral surface 21 of the grinding wheel 20 rotates at a faster rotational speed than the outer peripheral surface 11 of the workpiece 10. A difference in rotational speed between the outer peripheral surface 21 of the grinding wheel 20 and the outer peripheral surface 11 of the workpiece 10 causes a frictional force between the outer peripheral surface 11 and the outer peripheral surface 21 that are in contact with each other, and the outer peripheral surface 11 of the workpiece 10 is ground. Is done.

  As described above, the grinding wheel 20 is inclined in a direction away from the blade 50 as its axis 24 moves to the right side. For this reason, the outer peripheral surface 11 of the workpiece 10 mainly comes into contact with the left portion of the ridge line 21A (see FIG. 4) of the grinding wheel 20 and is ground. As a result, the outer peripheral surface 11 of the work 10 is provided with a taper with a narrow left side.

  After such grinding, as shown in FIG. 5, the stopper 70 is lowered until the upper surface 72 of the stopper 70 becomes the same height as the support surface 51, and the workpiece 10 is removed by the discharging means (not shown) by the blade 50. The support surface 51 passes through the upper surface 72 of the stopper 70 and is discharged to the outside. The centerless grinding apparatus 100 can continuously grind the workpiece 10 by repeating such a series of operations on the workpiece 10 to be input. In addition, the workpiece | work 10 turns into a round bar-shaped ceramic heater which makes the front end side the one end side provided with the taper part through various processes after that, and is attached to a glow plug (not shown).

  Here, the outer peripheral surface 21 of the grinding wheel 20 continuously grinds the outer peripheral surface 11 of the workpiece 10, so that the outer peripheral surface 21 is worn and the abrasive grains 23 constituting the grinding wheel 20 fall off from the outer peripheral surface 21. There is a case. In this case, in the range facing the notch 53 of the blade 50 in the outer peripheral surface 21 of the grinding wheel 20, the abrasive grains 23 falling off from the outer peripheral surface 21 enter the notch 53 as shown in FIG. 6. Here, if the depth of the notch 53 is 0.2 mm, for example, if the maximum particle size of the abrasive grain 23 is about 0.1 mm, the abrasive 23 can completely enter the notch 53. Since the entering abrasive grains 23 fall from the end of the notch 53 on the grinding wheel 20 side or the adjustment wheel 30 side, the abrasive grains 23 do not slide on the outer peripheral surface 11 of the workpiece 10. Therefore, in the range of the outer peripheral surface 11 of the workpiece 10 facing the notch 53 of the blade 50, scratches generated on the outer peripheral surface 11 can be prevented.

  In the range where the outer peripheral surface 11 of the workpiece 10 does not face the notch 53 of the workpiece 10 (that is, the range on the left side of the notch 53), the abrasive grains 23 dropped from the outer peripheral surface 21 of the grinding stone 20 are: Sliding with the outer peripheral surface 11 causes scratches on the outer peripheral surface 11. However, if the cutting depth of the taper provided on the outer peripheral surface 11 of the workpiece 10 is equal to or larger than the maximum particle size of the abrasive grains 23, the scratches disappear as a result of the outer peripheral surface 11 being ground. For this reason, the centerless grinding apparatus 100 can perform taper processing without causing scratches on the outer peripheral surface 11 of the workpiece 10 in the left-right direction.

  Further, in the longitudinal direction of the blade 50, the length of the notch 53 is ½ or less of the entire length of the workpiece 10. Accordingly, since the support surface 51 of the blade 50 supports more than half of the entire length of the workpiece 10, the centerless grinding apparatus 100 can support the workpiece 10 stably.

  In addition, since the corner portion 52 of the blade 50 is rounded, the workpiece 10 is not caught by the corner portion 52 even when the workpiece 10 may move in the left-right direction. Therefore, the workpiece 10 can move stably.

  The present invention can be variously modified. In the above-described embodiment, the centerless grinding apparatus 100 is an infeed type centerless grinding apparatus. However, the centerless grinding apparatus 100 is not limited to this, and the gap between the grinding wheel 20 and the adjustment wheel 30 facing each other in the longitudinal direction of the blade 50 is not limited thereto. May be a through-feed type centerless grinding apparatus provided with a conveying means for conveying the workpiece 10. In this case, the presser roller 60 and the stopper 70 may be omitted. In the case of a through-feed type centerless grinding apparatus, the blade 50 may support the workpiece 10 from the upper side, not from the lower side.

  Regardless of whether it is an in-feed type or a through-feed type, the grinding wheel 20 and the adjustment wheel 30 are not limited to a columnar shape, and may be a cylindrical shape or a shape whose outer periphery is a conical shape. Further, the axis 24 of the grinding wheel 20 and the axis 34 of the adjustment wheel 30 may be parallel or non-parallel to the longitudinal direction of the blade 50. Various combinations of the shapes of the grinding wheel 20 and the adjusting wheel 30 and the directions of the axis 24 and the axis 34 are possible. Further, as long as the support surface 51 of the blade 50 extends in the left-right direction, the support surface 51 may not be horizontal but may be inclined so that the end portion on the adjustment wheel 30 side is lowered. Further, the support surface 51 of the blade 50 may be disposed at a position lower than the axes of the grinding wheel 20 and the adjustment wheel 30. In this case, the workpiece 10 is ground in a gap below the axis of the grinding wheel 20 and the adjustment wheel 30.

  In the present embodiment, the outer peripheral surface 11 corresponds to an “outer periphery”, the outer peripheral surface 21 corresponds to a “surface”, and the support surface 51 corresponds to an “end surface”.

DESCRIPTION OF SYMBOLS 10 Workpiece 11 Outer peripheral surface 20 Grinding wheel 21 Outer peripheral surface 23 Abrasive grain 30 Adjustment wheel 50 Blade 51 Support surface 52 Corner part 53 Notch part 100 Centerless grinding apparatus

Claims (5)

A centerless grinding device for grinding the outer periphery of a workpiece,
A grinding wheel for grinding the outer periphery of the workpiece;
An adjustment wheel that is disposed on the opposite side across the workpiece as viewed from the grinding wheel, and that gives thrust to the workpiece toward the grinding wheel side;
It is arranged in a gap between the grinding wheel and the adjusting wheel, supports the workpiece, extends along a longitudinal direction of the workpiece to a part of an end surface facing the workpiece, and falls off the surface of the grinding wheel. A centerless grinding apparatus comprising a blade having a notch for allowing abrasive grains to escape.   2. The centerless grinding apparatus according to claim 1, wherein in the longitudinal direction of the workpiece, the length of the notch is less than or equal to half of the length of the workpiece.   3. The centerless grinding apparatus according to claim 1, wherein a depth of the notch that is recessed in a direction away from the workpiece is equal to or greater than a grain size of the abrasive grains.   4. The centerless grinding apparatus according to claim 1, wherein the blade is separated from the workpiece in a range where the notch is provided. 5.   The centerless grinding apparatus according to any one of claims 1 to 4, wherein a corner of the end surface on the cutout side is chamfered.

Images