Patent Description:
Patent Document <NUM>, on which the preamble of claims <NUM>, <NUM> is based, discloses a machine tool provided with a dustproof cover device capable of closing a vertical opening of a machine frame where a moving unit travels. The dustproof cover device comprises a base cover secured to the moving unit, an end cover arranged furthest from the moving unit to close an end of the vertical opening, and five intermediate covers arranged therebetween. The end cover and the intermediate covers are respectively formed in an L-shape of a guide and a cover. The guide is above the moving unit and extends in a moving direction. The cover is perpendicular to the guide and spreads over the vertical opening. The base cover, the end cover, and the intermediate covers overlap each other in a slidable manner. <CIT> and <CIT> disclose further prior art.

The conventional L-shape intermediate covers are respectively formed thinner than the base cover and other covers. Such thinner cover has a low resistance to external force caused by chips, lubricant, and dusts caught in a gap between the intermediate covers. That possibly causes deformation of and damage to the intermediate covers.

The present invention discloses a shutter device and a machine tool capable of preventing deformation and damage of a component.

The problem is solved by a shutter device according to claim <NUM> and a shutter device according to claims <NUM>.

According to the structure described above, the plurality of shutter plates of the second shutter respectively has the coupling unit provided in the second plate. The shutter plates coupled by the coupling unit have an improved resistance. Deformation of the shutter plate and damage thereto is thereby prevented.

A machine tool provided with a shutter device of the invention can be regarded as an invention.

The drawings only schematically show an example of the invention. They may have a mismatch in shape or proportion and an omission of illustration. Such mismatch and omission if any does not affect the explanation.

<FIG> simply shows a tool post <NUM> of the embodiment in a perspective view. <FIG> shows part of a lathe <NUM> provided with the tool post <NUM> as seen from front. The lathe <NUM> is an example of the machine tool. Each unit of the lathe <NUM> such as a spindle <NUM> and the tool post <NUM> may be numerically controlled by a not-shown NC (numerical control) apparatus to machine a workpiece W.

The spindle <NUM> holding the bar workpiece W may be rotated on a Z-axis. A tool (not shown) may be attached to the tool post <NUM>. The tool post <NUM> may have a rotating apparatus called a turret <NUM> having a plurality of surfaces where a plurality of tools are attached. The turret <NUM> may be rotated to switch the tools for use in machining the workpiece W.

The spindle <NUM> may be arranged on an S1 side in an X-direction with respect to the tool post <NUM> as shown in <FIG>. The X-direction may be perpendicular to the Z-axis. The tool post <NUM> may move in the X-direction, which may be an example of the predetermined direction. The tool post <NUM> may be an example of the moving unit. The X-direction may be oblique to the horizontal direction in <FIG> and <FIG>. The S1 side in the X-direction may be upper while the other S2 side may be lower.

Part of the tool post <NUM> may be enclosed in a casing <NUM> as shown in <FIG>. The casing <NUM> has a surface <NUM> parallel to the Z-axis where an opening (<NUM> in <FIG>) may be formed, through which the other part of the tool post <NUM> including the turret <NUM> may protrude outside the casing <NUM>. The surface <NUM> may be regarded as a frame for the opening <NUM> if the opening <NUM> is formed in part of the surface <NUM>. If the opening <NUM> is formed substantially entirely over the surface <NUM>, the edges of the plurality of surfaces surrounding the surface <NUM> may be regarded as the frame for the opening <NUM>.

The side that the tool post <NUM> protrudes outside the casing <NUM> may be called a front side for explanation. The direction parallel to the Z-axis may be called a front-back direction. A cover <NUM> may be attached in front of the surface <NUM> of the casing <NUM> to cover the edge of the surface <NUM> (<FIG>). The cover <NUM> is not shown in <FIG>, where the contours of the casing <NUM> as seen from fron is simply represented by a square. The cover <NUM> may be further in front than a shutter device <NUM> described later. In <FIG>, the surfaces of the casing <NUM> except the surface <NUM> are not shown to make part of the tool post <NUM> enclosed in the casing <NUM> visible.

The tool post <NUM> may move or rotate the turret <NUM> under numerical control. The tool post <NUM> may move to the S1 side in the X-direction to approach the spindle <NUM>. The tool post <NUM> may move to the S2 side in the X-direction to leave the spindle <NUM>. When the tool post <NUM> moves in the X-direction, the casing <NUM> may remain stationary. The tool post <NUM> may be movable in a direction perpendicular to the X-direction and the Z-axis. The tool post <NUM> may be movable in the front-back direction together with the casing <NUM>. The lathe <NUM> may include another spindle, another tool post, and a guide bush as required in addition to the configuration shown in <FIG>.

The shutter device <NUM> may have a structure covering the opening <NUM>. The shutter device <NUM> may thereby close the casing <NUM> to prevent invasion of chips scattered from the workpiece W, lubricant applied to the workpiece W, and other dusts (collectively called the chips) into the casing <NUM>. The shutter device <NUM> may cover the whole of the opening <NUM> (except the area occupied by the tool post <NUM> passing the opening <NUM>). The shutter device <NUM> may cooperate with another component to cover the opening <NUM>. The shutter device <NUM> may cover a portion of the opening <NUM> with the other portion remained uncovered.

The shutter device <NUM> may comprise a first shutter <NUM> and a second shutter <NUM>. The first shuter <NUM> may be a plate covering a certain portion of the opening <NUM>, which may be an area around the tool post <NUM> and an area on the S2 side. The first shutter <NUM> may be directly or indirectly secured to the tool post <NUM>.

The second shutter <NUM> may be arranged between the first shutter <NUM> and an end of the opening <NUM> on the S1 side. The second shutter <NUM> may expand and contract in the X-direction as the tool post <NUM> moves. The second shutter <NUM> may comprise a plurality of shutter plates <NUM> overlapping each other. The shutter plate <NUM> may have a first plate <NUM> and a second plate <NUM>. The first plate <NUM> may be longitudinally extended in the X-direction. The second plate <NUM> may be longitudinally extended in a direction perpendicular to the first plate <NUM>. The overlapping direction of the shutter plates <NUM> may be the front-back direction. The shutter plate <NUM> may be an L-shape plate consisting of the first plate <NUM> and the second plate <NUM>. The longitudinal direction of the first plate <NUM> may be generally parallel to the X-direction. The direction may include a direction with an incline within an error range. The longitudinal direction of the second plate <NUM> may be generally perpendicular to the X-direction. The direction may include a direction with an incline within an error range.

<FIG> and <FIG> each shows a sectional view taken along A-A line of <FIG>. The tool post <NUM> and others are easy-to-view without hatching. The cover <NUM> (not shown in <FIG>) is shown in <FIG> and <FIG>, and further in <FIG>, <FIG>, <FIG>, and <FIG>. <FIG> shows the state that the second shutter <NUM> expands or the state that the tool post <NUM> is in a position on the S2 side. <FIG> shows the state that the second shutter <NUM> contracts or the state that the tool post <NUM> is in a position on the S1 side. The first shutter <NUM> may be secured to the tool post <NUM> with a screw <NUM>. The first shutter <NUM> may move in the X-direction in conjunction with movement of the tool post <NUM> in the X-direction.

The second shutter <NUM> may include eight shutter plates <NUM>. The number of shutter plates <NUM> may be more than eight or less than eight. The shutter plate <NUM> closest to the S1 side is denoted by 53a and the other plates are respectively denoted by 53b, 53c, 53d, 53e, 53f, <NUM>, and <NUM> in that order. As shown in <FIG>, the shutter plate 53a closest to the S1 side may be in a frontmost position while the shutter plate <NUM> furthest from the S1 side may be in a backmost position. The first shutter <NUM> may be arranged at the back of the shutter plate <NUM> in the backmost position.

The first plate <NUM> of the shutter plate <NUM> may have a force receiving part <NUM> which receives an X-direction force from the first shutter <NUM>. <FIG> and <FIG> each shows a sectional view taken along B-B line of <FIG> passing the first plate <NUM>. <FIG> shows the state that the second shutter <NUM> expands. <FIG> shows the state that the second shutter <NUM> contracts. The tool post <NUM> is not shown.

As shown in <FIG>, the first plate <NUM> of the shutter plate <NUM> may have a slit penetrating the first plate <NUM> in the front-back direction. The slit may be longitudinally extended in the X-direction. The slit may be an example of the force receiving part <NUM>. The force receiving part <NUM> may be formed in the first plate <NUM> of every and each shutter plate <NUM>. The force receiving parts <NUM> may be formed in positions overlapping each other. In <FIG> and <FIG>, the force receiving part of the shutter plate 53a is denoted by 56a and the other force receiving parts are respectively denoted by 56b, 56c, 56d, 56e, 56f, <NUM> and <NUM> in that order.

The first shutter <NUM> may have a protrusion <NUM> in a position corresponding to the force receiving part <NUM> of the shutter plate <NUM>. The protrusion <NUM> may protrude toward the overlapping shutter plates <NUM>. The protrusion <NUM> protruding to the front may be inserted in the force receiving parts 56a, 56b, 56c, 56d, 56e, 56f, <NUM>, and <NUM>. The protrusion <NUM> may be longitudinal in the X-direction and fastened to the first shutter <NUM> with a screw <NUM> (<FIG> and <FIG>). The protrusion <NUM> as caught in the force receiving parts 56a, 56b, 56c, 56d, 56e, 56f, <NUM>, and <NUM> may move in the X-direction integrally with the first shutter <NUM>. The protrusion <NUM> may be an example of a first protrusion. In <FIG> and <FIG>, the protrusion <NUM> and others are shown without hatching for easy-to see purpose.

The slits (the force receiving parts 56a, 56b, 56c, 56d, 56e, 56f, <NUM>, and <NUM>) may be different in length in the X-direction (<FIG> and <FIG>). Particularly, the force receiving part <NUM> of the shutter plate <NUM> closer to the end of the opening <NUM> on the S1 side is longer in the X-direction. Specifically, the force receiving part 56a of the shutter plate 53a may be the longest while the force receiving part <NUM> of the shutter plate <NUM> may be the shortest.

When the tool post <NUM> with the first shutter <NUM> moves from the S2 side to the S1 side, the end of the protrusion <NUM> on the S1 side may sequentially hit the end of each force receving part <NUM> on the S1 side from <NUM> to 56a in that order. Each of the shutter plates <NUM> may receive pushing force toward the S1 side and thereby sequentially start to move toward the S1 side from <NUM> to 53a in that order. As the result, the shutter plates 53a to <NUM> may overlap each other in a position on the S1 side to bring the second shutter <NUM> into a contracted state as shown in <FIG> and <FIG>. Finally, the second plates <NUM> of the shutter plates 53a, 53b, 53c, 53d, 53e, 53f, <NUM>, and <NUM> may almost entirely overlap each other when contration of the second shutter <NUM> is complete as shown in <FIG>.

When the tool post <NUM> with the first shutter <NUM> moves from the S1 side to the S2 side, the end of the protrusion <NUM> on the S2 side may sequentially hit the end of each force receving part <NUM> on the S2 side from <NUM> to 56a in that order. Each of the shutter plates <NUM> may receive pushing force toward the S2 side and thereby sequentially start to move toward the S2 side from <NUM> to 53a in order. As the result, the second shutter <NUM> is brought into an expanded state.

As described above, the second shutter <NUM> may expand and contract in the X-direction when the first plate <NUM> of the shutter plates <NUM> of the second shutter <NUM> receives the X-direction force from the first shutter <NUM> through the force receiving part <NUM>. Even in the state that expansion of the second shutter <NUM> is complete, part of the shutter plate <NUM> may still overlap part of the shutter plate <NUM> adjacent to in the front-back direction (<FIG>, <FIG>). A plate 41a as shown in <FIG> and <FIG> may be part of the surface <NUM> of the casing <NUM> where the opening <NUM> is not formed. The plate 41a may be in a position on the S2 side with respect to the tool post <NUM> to overlap at the back of the first shutter <NUM>. Even when the tool post <NUM> with the first shutter <NUM> moves to the S1 side, part of the opening <NUM> on the S2 side of the tool post <NUM> can be prevented from exposure by the plate 41a provided behind the first shutter <NUM> (<FIG>). The shutter device <NUM> of the invention keeps the opening <NUM> closed regardless of movement of the tool post <NUM> to whichever side in the X-direction.

The second plate <NUM> of the shutter plate <NUM> of the second shutter <NUM> may be provided with a coupling unit <NUM>. The coupling unit <NUM> may couple the shutter plates <NUM> mutually overlapping in the front-back direction movably in the X-direction relative to each other.

<FIG> is a perspective view showing end portions <NUM> of the second plates <NUM> of overlapping two shutter plates <NUM> as seen from the back. The end portion <NUM> of the second plate <NUM> may be opposite the other end portion of the second plate <NUM> to be connected to the first plate <NUM>. The two shutter plates <NUM> in <FIG> may be the shutter plates 53b and 53c.

<FIG> is a perspective view taken along C-C line of <FIG>, which passes the end portion <NUM> of the second plate <NUM> of the shutter plate <NUM>. <FIG> is a perspective view taken along D-D line of <FIG>, which passes the end portion <NUM> of the second plate <NUM> of the shutter plate <NUM>. The C-C line and the D-D line are also shown in <FIG>. They are deviated with respect to the longitudinal direction of the second plate <NUM> as shown in <FIG> and <FIG>.

The end portion <NUM> of the shutter plate <NUM> may be provided with a protrusion <NUM> and a recess <NUM>. The protrusion <NUM> may correspond to the second protrusion. A combination of the protrusion <NUM> and the recess <NUM> may be an embodiment of the coupling unit <NUM>. The protrusion <NUM> formed in one shutter plate <NUM> may be inserted in the recess <NUM> formed in another shutter plate <NUM> overlapping at the back. The recess <NUM> formed in one shutter plate <NUM> may receive the protrusion <NUM> formed in another shutter plate <NUM> overlapping at the front as shown in <FIG>, <FIG>, and <FIG>. There may be two types of the end portion <NUM> having different positional relationships of the protrusion <NUM> and the recess <NUM>. The recess <NUM> may be in a predetermined position nearer the first plate <NUM> with respect to the longitudinal direction of the second plate <NUM> than the protrusion <NUM> may be (the end portion <NUM> of the first type). The protrusion <NUM> may be in a predetermined position nearer the first plate <NUM> with respect to the longitudinal direction of the second plate <NUM> than the recess <NUM> may be (the end portion <NUM> of the second type).

The plurality of shutter plates <NUM> may overlap each other in the front-back direction in such manner as the end portion <NUM> of the first type and the end portion <NUM> of the second type are alternately arranged. In <FIG>, the shutter plate 53b at the front may have the end portion <NUM> of the second type while the shutter plate 53c at the back may have the end portion <NUM> of the first type. In <FIG> and <FIG>, the shutter plates 53a, 53c, 53e, and <NUM> respectively may have the end portion <NUM> of the first type while the shutter plates 53b, 53d, 53f, and <NUM> respectively may have the end portion <NUM> of the second type. Accordingly, the protrusion <NUM> of the end portion <NUM> of the first type may be inserted in the recess <NUM> of the end portion <NUM> of the second type of the shutter plate <NUM> overlapping at the back. Then, the protrusion <NUM> of the end portion <NUM> of the second type may be inserted in the recess <NUM> of the end portion <NUM> of the first type of the shutter plate <NUM> overlapping on the further back side. Such engagement may be sequentially repeated for the plurality of shutter plates <NUM> overlapping in the front-back direction.

The recess <NUM> in <FIG> may be a through-hole penetrating the shutter plate <NUM> in the front-back direction. Thickness of the protrusion <NUM> in the front-back direction (a degree of protrusion) may be less than the depth of the recess <NUM> in the front-back direction. Thickness of the shutter plate <NUM> may equal to the depth of the recess <NUM> in <FIG> where the recess <NUM> is a through-hole. The recess <NUM> may not be a through-hole. The recess <NUM> may be a hollow only capable of receiving the protrusion <NUM> of the overlapping shutter plate <NUM>.

A combination of the protrusion <NUM> protruding from one shutter plate <NUM> toward the other overlapping shutter plate <NUM> and the recess <NUM> formed in the other shutter plate <NUM> to receive the protrusion <NUM> may correspond to the coupling unit <NUM> coupling the two shutter plates <NUM>. In <FIG>, the recess <NUM> may be an elongated hole extended in the X-direction. The overlapping two shutter plates <NUM> can move in the range of the length of the recess <NUM> (the elongated hole) in the X-direction relative to each other.

The coupling structure by the coupling unit <NUM> may be applied to the relation between the cover <NUM> and the frontmost shutter plate 53a and to the relation between the backmost shutter plate <NUM> and the first shutter <NUM>. The cover <NUM> facing the end portion <NUM> of the second plate <NUM> of the shutter plate 53a may be provided with the protrusion <NUM> protruding toward the back (<FIG>). The protrusion <NUM> of the cover <NUM> may be inserted in the recess <NUM> of the shutter plate 53a. The first shutter <NUM> facing the end portion <NUM> of the second plate <NUM> of the shutter plate <NUM> may be provided with the recess <NUM>. The recess <NUM> of the first shutter <NUM> may receive the protrusion <NUM> protruding from the shutter plate <NUM> toward the back. Accordingly, the cover <NUM> secured to the casing <NUM>, the plurality of shutter plates <NUM>, and the first shutter <NUM> moving in the X-direction in conjunction with movement of the tool post <NUM> may be continuously coupled by the coupling units <NUM> provided between the mutually overlapping members.

The protrusion <NUM> may protrude to whichever direction. It may protrude to the front side instead of the back side. The protrusion <NUM> of the shutter plate <NUM> protruding forwards may be inserted in the recess <NUM> of the other shutter plate <NUM> overlapping at the front. The recess <NUM> of the shutter plate <NUM> may receive the protrusion <NUM> of the shutter plate <NUM> overlapping at the back.

The structure of the coupling unit <NUM> may have variations. There may be the shutter plate <NUM> provided with two protrusions <NUM>, one protruding forwards and the other protruding backwards. There may be the other shutter plate <NUM> provided with two recesses <NUM> overlapping the shutter plate <NUM> having the two protrusions <NUM>. Particularly, there may be the end portion <NUM> of the third type having the protrusion <NUM> protruding forwards and the protrusion <NUM> protruding backwards. The backward protrusion <NUM> may be in a predetermined position deviated with respect to the forward protrusion <NUM> in the longitudinal direction of the second plate <NUM>. There may be further the end portion <NUM> of the fourth type having the recess <NUM> opened at least forwards and the recess <NUM> opened at least backwards. The backward recess <NUM> may be in a predetermined position deviated with respect to the forward recess <NUM> in the longitudinal direction of the second plate <NUM>. The plurality of shutter plates <NUM> may overlap each other in the front-back direction in such manner as the end portion <NUM> of the third type and the end portion <NUM> of the fourth type are alternately arranged. Accordingly, the backward protrusion <NUM> of the end portion <NUM> of the third type may be inserted in one of the recesses <NUM> of the end portion <NUM> of the fourth type of the shutter plate <NUM> overlapping at the back. Then, the other of the recesses <NUM> of the end portion <NUM> of the fourth type may receive the forward protrusion <NUM> of the end portion <NUM> of the third type of the shutter plate <NUM> overlapping on the further back side. Such engagement may be sequentially repeated for the plurality of shutter plates <NUM> overlapping in the front-back direction.

The width of the end portion <NUM> in the X-direction may be different from that of a longitudinal portion <NUM> of the second plate <NUM> (a portion nearer the first plate <NUM> than the end portion <NUM>) as shown in <FIG> and <FIG>. The longitudinal portion <NUM> may be narrower than the end portion <NUM> in the X-direction. The end portion <NUM> may necessarily have enough width in the X-direction for the protrusion <NUM> and the recess <NUM> serving as the coupling unit <NUM>. The longitudinal portion <NUM> without the coupling unit <NUM> may be formed in a narrower shape.

According to the embodiment, the shutter device <NUM> may move in conjunction with movement of the tool post <NUM> in the predetermined X-direction to close part of the opening <NUM>. The shutter device <NUM> may comprise the first shutter <NUM> moving in the X-direction in conjunction with movement of the tool post <NUM> and the second shutter <NUM> arranged between the end of the opening <NUM> and the first shutter <NUM>. The second shutter <NUM> may expand and contract in the X-direction in conjunction with movement of the tool post <NUM>. The second shutter <NUM> may have the plurality of shutter plates <NUM>. The shutter plate <NUM> may have the first plate <NUM> longitudinally extended in the X-direction and the second plate <NUM> longitudinally extended in a direction perpendicular to the first plate <NUM>. The second plate <NUM> of the shutter plate <NUM> may be provided with the coupling unit <NUM> which couples the overlapping shutter plates <NUM> in a manner that they can move in the predetermined direction relative to each other. The shutter plates <NUM> coupled by the coupling unit <NUM> formed in the second plate <NUM> may have improved resistance to deformation.

<FIG> shows one of the shutter plates <NUM> of the second shutter <NUM> for explanation of a problem to be solved by the embodiment of the invention. The shutter plate <NUM> may move in the X-direction as the tool post <NUM> moves in the X-direction. It is quite possible that smooth movement of the shutter plate <NUM> is hindered by unnecessary external force applied to the shutter plate <NUM> when chips are caught in a gap between the mutually overlapping shutter plates <NUM>. It is being assumed that the chips enter the gap between the end portions <NUM> of the two overlapping shutter plates <NUM>. When the shutter plate <NUM> overlapping at the back starts to move toward the S1 side as the tool post <NUM> starts to move to the S1 side in the X-direction, the second plate <NUM> of the shutter plate <NUM> starting to move may receive the force Q (<FIG>) due to invasion of the chips. It is quite possible that the second plate <NUM> of the shutter plate <NUM> receiving the force Q is deformed toward the S2 side as shown by a broken line.

Deformation of the second plate <NUM> applies great load to a root thereof, which is a place connecting the second plate <NUM> and the first plate <NUM>. Applied load possibly causes a crack in the root and damage to the shutter plate <NUM>. In the embodiment, however, the shutter plates <NUM> can be mutually supported by each other by the coupling unit <NUM> formed in the second plate <NUM> to improve resistance to unnecessary external force. Deformation of the shutter plate <NUM> and damage thereto caused by deformation is thereby prevented.

The coupling unit <NUM> may be formed in the end portion <NUM> opposite the root connecting the second plate <NUM> and the first plate <NUM>. The force Q applied to the end portion <NUM> of the second plate <NUM> distant from the root thereof would increase load applied to the root and thereby easily cause damage to the shutter plate <NUM>. The coupling unit <NUM> formed in the end portion <NUM> could prevent deformation of the shutter plate <NUM> against external force generated due to invasion of chips into the end portion <NUM>. Damage to the shutter plate <NUM> could be thereby prevented.

The coupling unit <NUM> may, however, be formed in another place of the second plate <NUM>. For example, the coupling unit <NUM> may be provided in both the end portion <NUM> and the longitudinal portion <NUM> respectively or only in the longitudinal portion <NUM>.

The longitudinal portion <NUM> of the second plate <NUM> of the shutter plate <NUM> may be of a shape narrower than the end portion <NUM> in width in the X-direction. Such configuration could bring the tool post <NUM> closest to the end of the opening <NUM> to be in a position closest to the spindle <NUM> on the S1 side when contraction of the second shutter <NUM> is complete.

At least part of the longitudinal portion <NUM> may be the same as the end portion <NUM> in width in the X-direction or wider than the end portion <NUM>.

In the embodiment, the coupling unit <NUM> may comprise the second protrusion (the protrusion <NUM>) protruding from one shutter plate <NUM> toward the other shutter plate <NUM> overlapping each other and a hole (the recess <NUM>), whose width in the X-direction is longer than the protrusion <NUM>, formed in the other shutter plate <NUM> to receive the protrusion <NUM>. The adjacent shutter plates <NUM> may be coupled by engagement of the protrusion <NUM> formed in one shutter plate <NUM> and the recess <NUM> formed in the other shutter plate <NUM>. The recess <NUM> may be elongated in the X-direction (<FIG>), which shortens the recess <NUM> in width in the longitudinal direction of the second plate <NUM>. Such configuration could shorten the end portion <NUM> in width in the longitudinal direction of the second plate <NUM> while the end portion <NUM> may have the protrusion <NUM> and the recess <NUM> deviated to each other with respect to the longitudinal direction of the second plate <NUM>.

The shape of the coupling unit <NUM> may not be limited to the protrusion <NUM> and the recess <NUM> as described above. The coupling unit <NUM> may be any device capable of coupling the adjacent overlapping shutter plates <NUM> in a manner that they are relatively movable in the X-direction.

The first plate <NUM> of the shutter plate <NUM> may have the force receiving part <NUM> which receives the X-direction force from the first shutter <NUM>. The shutter plates <NUM> of the second shutter <NUM> may receive the X-direction force from the first shutter <NUM> through the force receiving part <NUM> formed in the first plate <NUM>. The second shutter <NUM> may thereby expand and contract.

The first shutter <NUM> may be provided with the first protrusion (the protrusion <NUM>) protruding toward the overlapping shutter plates. The force receiving part <NUM> formed in the first plate <NUM> of the shutter plate <NUM> may be a slit penetrating through the first plate <NUM> and elongated in the X-direction to receive the protrusion <NUM>. The slit of the shutter plate <NUM> may be longer in the X-direction as the shutter plate <NUM> is closer to the end of the opening <NUM>. The protrusion <NUM> may move inside the slit (the force receiving part <NUM>) of the shutter plate <NUM> in conjunction with movement of the first shutter <NUM>. The shutter plates <NUM> may consecutively move in the X-direction in order, resulting in expansion and contraction of the second shutter <NUM>.

Both the slit (the force receiving part <NUM>) and the protrusion <NUM> inserted in the slit may be of an elongated shape in the X-direction. When the protrusion <NUM> move inside the slit in the X-direction, the X-direction force from the first shutter <NUM> moving in the X-direction may be appropriately conveyed to each shutter plate <NUM> of the second shutter <NUM>. The shutter plate <NUM> is thereby restricted to move in a direction perpendicular to the X-direction. The shutter plate <NUM> can smoothly move without an inclination with respect to the X-direction or with little inclination if any.

The force receiving part <NUM> may be provided in the second plate <NUM> of the shutter plate <NUM>. For example, the force receiving part <NUM> may be formed in the longitudinal portion <NUM> of the second plate <NUM> of the shutter plate <NUM> in the furthest position on the S2 side. The force receiving part <NUM> formed in the second plate <NUM> may receive force toward the S1 side or the S2 side from the first shutter <NUM>. The second shutter <NUM> may expand and contract accordingly.

<FIG> and <FIG> respectively show another embodiment of the coupling unit <NUM>. The drawing shows a rear view of part of the end portions <NUM> of the second plates <NUM> of the shutter plates <NUM> overlapping in the front-back direction. The protrusion <NUM> and the recess <NUM> may be formed in an end portion 551b of the shutter plate 53b. The protrusion <NUM> and the recess <NUM> may be also formed in an end portion 551c of the shutter plate 53c. The protrusion <NUM> of the end portion 551b may be inserted in the recess <NUM> of the end portion 551c.

The protrusion <NUM> in <FIG> may be smaller than that in <FIG>. The protrusion <NUM> in <FIG> may be of such size as not touching an edge of the recess <NUM> when the second shutter <NUM> normally moves in conjunction with movement of the tool post <NUM> with the first shutter <NUM>. Normal movement of the second shutter <NUM> may mean that each shutter plate <NUM> can move in the X-direction without deformation possibly caused by the force Q as described above or other unnecessary external force. The protrusion <NUM> may move within the recess <NUM> in the X-direction by engagement of the protrusion <NUM> of the first shutter <NUM> with the force receiving part <NUM>. The protrusion <NUM> may be of such size as not touching the edge of the recess <NUM> when the second shutter <NUM> normally moves. That prevents constant occurrence of friction between the protrusion <NUM> and the recess <NUM> during movement of the second shutter <NUM>. When the second shutter starts to move, the shutter plate <NUM> may start to deform due to the external force to bring the protrusion <NUM> in <FIG> into contact with the edge of the recess <NUM>. Such engagement of the protrusion <NUM> and the recess <NUM> may bring the shutter plates <NUM> to be in a substantially coupled state by the coupling unit <NUM>. The plurality of shutter plates <NUM> are thereby supported by each other, which prevents deformation of the shutter plate due to the external force.

The coupling unit <NUM> in the embodiment may include a structure always keeping engagement of the shutter plates and further include another structure bringing the engagement only in an abnormal condition caused by, for example, unnecessary external force.

The recess <NUM> may be an elongated hole longer than the protrusion <NUM> in length in the X-direction. The recess <NUM> may not be limited to the hole elongated in the X-direction as in <FIG> and <FIG>. The recess <NUM> may be a circular hole as in <FIG>. The protrusion <NUM> may be still of a size as not touching the edge of the recess <NUM> during normal movement of the second shutter <NUM>.

The X-direction along which the tool post <NUM> moves may be horizontally inclined. The side S1 closer to the spindle <NUM> may be upper while the side S2 further from the spindle <NUM> may be lower. Accordingly, it is quite possible that accumulation of chips is heavier on a surface of the shutter device <NUM> on the S2 side because of gravity than on a surface thereof on the S1 side. In this embodiment, the surface on the S2 side of the shutter device <NUM> may be formed of the first shutter <NUM> of a single plate while the surface on the S1 side may be formed of the plurality of L-shape shutter plates <NUM>. Such configuration can reduce accumulation of chips on the shutter device <NUM> compared to a structure that a plurality of overlapping plates forms the surface on the S2 side. Further in this embodiment, the plurality of shutter plates <NUM> may overlap each other in a manner that the shutter plate <NUM> on the S1 side is at the front while the shutter plate <NUM> on the S2 side is at the back. Such configuration can prevent invasion of chips into between the shutter plates compared to a structure that the shutter plates <NUM> may overlap each other in a manner that the shutter plate <NUM> on the S1 side is at the back while the shutter plate <NUM> on the S2 side is at the front.

Claim 1:
A shutter device (<NUM>) which moves in conjunction with movement of a moving unit in a predetermined direction comprising:
a first shutter (<NUM>) which moves in the predetermined direction in conjuction with movement of the moving unit to cover part of an opening (<NUM>); and
a second shutter (<NUM>) arranged between an end of the opening (<NUM>) and the first shutter (<NUM>) to expand and contract in the predetermined direction in conjunction with movement of the moving unit,
wherein the second shutter (<NUM>) comprises a plurality of shutter plates (<NUM>) overlapping each other, each of which having a first plate (<NUM>) whose longitudinal direction is along the predetermined direction and a second plate (<NUM>) whose longitudinal direction is along a perpendicular direction to the first plate (<NUM>),
the first plate (<NUM>) of the shutter plates (<NUM>) of the second shutter (<NUM>) is provided with a force receiving part (<NUM>) which receives a force toward the predetermined direction from the first shutter (<NUM>),
the shutter device (<NUM>) being characterised in that
the second plate (<NUM>) of the shutter plates (<NUM>) of the second shutter (<NUM>) is provided with a coupling unit (<NUM>) which couples the overlapping shutter plates (<NUM>) in a manner that they can move in the predetermined direction relative to each other,
the first shutter (<NUM>) is provided with a first protrusion (<NUM>) protruding toward the overlapping shutter plates (<NUM>),
the force receiving part (<NUM>) is a slit elongated in the predetermined direction and penetrating the first plate (<NUM>) to receive the first protrusion (<NUM>), and
each slit is longer in the predetermined direction as the shutter plate (<NUM>) is closer to the end of the opening (<NUM>).