A boring device according to one embodiment of the present invention includes: a cutting edge; a drive unit that rotationally drives the cutting edge; a feed flow path through which a cooling liquid is fed to the cutting edge; and a tube pump that forces the cooling liquid in the feed flow path to flow to the cutting edge. The tube pump includes a feed tube constituting a part of the feed flow path and a first pressing mechanism that presses the feed tube, and the first pressing mechanism is driven by the drive unit.

A method for manufacturing a continuous drill ring for a core drill bit is disclosed. The method includes forming at least two green compacts in layers in a direction of formation between a bottom side and a top side by successively applying powder layers containing a powder mixture and diamond layers containing diamond particles that are arranged in a set pattern, shaping the green compacts into ring segments under the effect of pressure, sintering the ring segments under the effect of heat, and combining the sintered ring segments in a circular manner and joining the same in a frictionally engaging or integrally bonding manner at the lateral edges thereof so as to obtain the continuous drill.

A method for manufacturing a continuous drill ring for a core drill bit is disclosed. The method includes forming at least two green compacts in layers in a direction of formation between a bottom side and a top side by successively applying powder layers containing a powder mixture and diamond layers containing diamond particles that are arranged in a set pattern. The green compacts are shaped into ring segments under the effect of pressure. The ring segments are joined in a circular manner and they are sintered under the effect of heat so as to obtain a continuous drill ring.

There is provided a drill bit for cutting tiles comprising a hollow body portion bearing an annular cutting surface at one end and a wax plug located within the hollow body portion, wherein an internal wall of the hollow body portion has at least one region of reduced thickness so as to provide one or more channels along which melted wax can flow to reach cutting surface. The channels can be provided by an offset central passage within body portion, or as elongate grooves around the internal wall of the hollow body portion. The channels can be helical grooves.

A method for producing a twist drill has the following steps. A blank is shaped to form a semi-finished product. The semi-finished product is formed from a core, coaxial with the drill axis, having a radius and a number of webs, arranged on the core, having a height. The semi-finished product has a constant cross section along the drill axis. The webs have a first portion which adjoins the core and in which a width of the web remains constant or decreases in the circumferential direction with increasing radial distance from the drill axis. The webs have a second portion which adjoins the first portion and in which the width of the web increases in the circumferential direction with increasing radial distance from the drill axis. The webs of the semi-finished product are shaped into helical segments using a plurality of rolling tools that annularly enclose the semi-finished product and roll on the webs along the drill axis. The rolling tools have teeth that are inclined with respect to the drill axis. A height of the helical segments is less than the height the webs. Helical segments formed from adjacent webs are in contact with one another in a closing fold. The invention also relates to a twist drill.

A curved cover glass includes a plate-like glass body having a first surface, a second surface facing the first surface and at least one end face. The plate-like glass body has an average thickness of 5 mm or less. Among tangential directions on the first surface at an arbitrary point, when an X-axis is assumed to be a direction in which a first curvature radius R.sub.1 in cross-section of the first surface in an XZ plane is minimum, the first surface has a curvature part in which the surface is bent in the X-axis direction at least at one point on the first surface. The first curvature radius R.sub.1 is 10,000 mm or less. The curvature part includes at least one opening or concave part extending from the first surface to the second surface.

A curved cover glass includes a plate-like glass body having a first surface, a second surface facing the first surface and at least one end face. The plate-like glass body has an average thickness of 5 mm or less. Among tangential directions on the first surface at an arbitrary point, when an X-axis is assumed to be a direction in which a first curvature radius R.sub.1 in cross-section of the first surface in an XZ plane is minimum, the first surface has a curvature part in which the surface is bent in the X-axis direction at least at one point on the first surface. The first curvature radius R.sub.1 is 10,000 mm or less. The curvature part includes at least one opening or concave part extending from the first surface to the second surface.

The present disclosure provides a method for manufacturing a countertop, where a countertop workpiece may be easily secured to a workpiece-mounting device during the machining thereof, leading to good precision and standardization. This may be achieved using a suction of the countertop workpiece via air intake in the mounting device. Further, the present disclosure provides a countertop machining apparatus including a vacuum chamber divided into a multiple of vacuum sub-chambers disposed in a work table, and a suction panel disposed on the chamber. In this configuration, a number of the vacuum sub-chambers to be kept in a vacuum state may be adjusted. This may lead to a reduction of a power consumption required to suction the countertop workpieces.

The present disclosure provides a method for manufacturing a countertop, where a countertop workpiece may be easily secured to a workpiece-mounting device during the machining thereof, leading to good precision and standardization. This may be achieved using a suction of the countertop workpiece via air intake in the mounting device. Further, the present disclosure provides a countertop machining apparatus including a vacuum chamber divided into a multiple of vacuum sub-chambers disposed in a work table, and a suction panel disposed on the chamber. In this configuration, a number of the vacuum sub-chambers to be kept in a vacuum state may be adjusted. This may lead to a reduction of a power consumption required to suction the countertop workpieces.

A synthetic quartz glass substrate is machined by bringing a surface of the synthetic quartz glass substrate as the workpiece into contact with and superposing it on a surface of a protective member made of synthetic quartz glass to effect optical contact bonding of the workpiece and the protective member, and passing a cutting tool through the optical contact bonding surfaces. This machining process is able to effectively prevent the generation of microdefects at the cutting tool entry site and extraction site during a cutting operation. Moreover, a fixing agent is not used to join the workpiece and the protective member, and so productivity is high because there is no need for the application and later removal of a fixing agent.