MACHINE TOOL

Abstract: A machine tool capable of reducing the vibration of a spindle head to enable a high-precision machining, wherein a column (2) is mounted fixedly onto a bed (1), a first saddle (4) forming a square frame body of rectangular cross-section is mounted on the column (2) movably in vertical direction (f1), a second saddle (6) forming a square frame body (6a) smaller in size than the above square frame body is mounted inside the first saddle (4) movably in lateral direction (f2), a horizontal guide frame (6b) of a specified length is mounted on the rear surface of the square frame body (6a) of the second saddle (6) in the state of being crossed at right angle to the rear surface, rail members (5, 7) are laid down on square frame upper and lower prismatic bodies (4b, 4c) of the first saddle (4) and the horizontal guide frame (6b) of the second saddle (6), and concrete is filled sealingly into the square frame body of the first saddle (4) and / or the square frame body of the second saddle (6) and the horizontal guide frame (6b) so as to form a vibration damping structure body.

Description: FIELD OF THE INVENTION The present invention relates to a machine tool that a part of components is made of concrete. BACKGROUND OF THE INVENTION A conventional machine tool that shortens the length of a first saddle, a second saddle or a column in each spindle direction (longitudinal direction), and that accelerates a feed speed of a spindle head in the longitudinal direction, has been already disclosed in a prior art reference, for example, the Japanese Patent Provisional Publication No. 365529 of 1992, according to the preamble of claim 1. As shown therein, the machine tool is defined by the column mounted fixedly onto a bed in the spindle direction, the first saddle guided on the column movably in vertical direction, the second saddle guided on the first saddle movably in lateral direction, and the spindle guided on the second saddle movably in the longitudinal direction. The above first or second saddle is generally made of casting, and therefore the spindle head supported on these saddles sometimes vibrates to such an extent that affects machining precision in machining. DE 19745233 A1 refers to a spindle holding box for machine tools. The spindle holding structure comprises tubular elements forming the sidefaces of the spindle holding box. The tubular elements are filled with concrete. JP 04365529 A which forms the preamble of claim 1, refers to a machine tool comprising a first saddle which is movable in the horizontal direction and a second saddle which is movable in the vertical direction. An object of this invention is to provide a machine tool that reasonably prevents vibrations of the spindle head and the like and enables a high-precision machining. SUMMARY OF THE INVENTION To achieve the above object, a machine tool comprising the features of claim 1 is provided. Accordingly, the first saddle and the second saddle hardly vibrate, thereby effectively reducing vibrations of a spindle head and the like. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing a characteristic region of a machine tool in the present invention. Fig. 2 is a front view of the above characteristic region. Fig. 3 is a side view of the above characteristic region. Fig. 4 is a plane view of the above characteristic region. Fig. 5 shows a part of the above characteristic region, Fig. 5A is a perspective view of the first saddle, and Fig. 5B is a perspective view of the second saddle. PREFERRED EMBODIMENT OF THE PRESENT INVENTION To describe the present invention in detail, this is explained with reference to drawings. A machine tool comprises a bed 1 forming a lowermost part, a column 2 fixed on the upper surface of the bed 1, the first saddle 4 guided free-slidably in vertical direction f1 through a pair of guide rails 3 and 3 for upper and lower sides mounted fixedly onto the front surface of the column 2, the second saddle 6 guided free-slidably in lateral direction f2 through a pair of rail members 5 and 5 for right and left sides mounted fixedly onto the front surface of the first saddle 4, and a spindle head 8 guided free-slidably in longitudinal direction f3 through a pair of rail members 7 and 7 for front and back sides mounted fixedly on the second saddle 6. An explanation follows about the above components. That is, the bed 1 is formed into a box structure out of steel plates, and supporting members 9 and 9 are fixed on the upper surface of the bed 1 in front of the column 2 to fix a not-illustrated work-table. A drop hole 10 is provided at the center of the bed 1 to drop cutting chips and coolant into a specified position. The column 2 has a pair of right and left vertical parts 2a and 2a as well as a pair of upper and lower lateral parts 2b and 2c, and is mainly composed of a square frame body forming a comparative large square hole "a" for front and back sides to the center. A motor table 2d is provided to the upper lateral part 2b, and a servomotor I 1 is fixed thereon to drive vertically the first saddle 4. The first saddle 4, as shown in Fig. 5A and the like, has a pair of right and left vertical single prismatic bodies 4a and 4a of rectangular cross-section as well as a pair of upper and lower lateral single prismatic bodies 4b and 4c of rectangular cross-section, and forms a comparative large square hole "b" for front and back sides to the center. In addition, the first saddle 4 is provided with a vertical square frame body made of steel plates enough to accept in the front surface of the column 2. Interfitting members 12, which are guided by the rail members 3 and 3, are fixed on the rear surface of the square frame. A pair of rail members 5 and 5 are fixed on the front surfaces of the lateral prismatic bodies 4b and 4c so as to guide the second saddle 6. Moreover, a bracket 13 is fixed on the rear surface of the upper lateral prismatic body 4b in an inverse U letter shape at front sight, and a nut body 14 is fixed on the top of the bracket 13. In this case, single prismatic bodies 4a, 4b and 4c may be formed integrally out of a plurality of prismatic members of rectangular cross-section. The lateral prismatic bodies 4b and 4c are respectively filled with concrete "k" so as to be sealed in airtight. Here, the concrete "k" is used in a broad sense such as cement concrete, cement mortar, cement paste, plastics concrete and asphalt concrete. The concrete "k" may be filled over the full or partial length of the prismatic bodies 4a, 4b and 4c. In either case, the concrete "k" is filled over the whole section of a filled portion. The concrete "k" filled into the prismatic bodies 4b and 4c effectively increases rigidity and mass of the square frame body mainly composed of the first saddle 4. The concrete "k" is confined in airtight, thereby preventing water evaporating. Therefore, the concrete "k" is prevented an aged deterioration due to touching with the air. A vertical screw axis 15, which combines with an output axis of the servomotor 11, is screwed into the nut body 14. A servomotor 16 is provided on the upper surface of the upper lateral prismatic body 4b to drive the second saddle 6 in lateral direction. Besides, as shown in Fig. 5A, bearing members 19a and 19b, which support rotatively a lateral screw axis 18 that is combined with an output axis of the servomotor 16, are fixed on a pair of reinforcing plates 17 and 17 that are fixed on the prismatic body 4b. As shown in Fig. 5B and the like, the second saddle 6 forms a square hole "c" for front and back sides enough to contain the spindle head 8 to the center, and is provided with a vertical square frame body 6a enough to accept the front surface of the first saddle 4. Here, a pair of right and left horizontal guide frames 6b and 6b comprising square cylinder members made of steel plates are secured on the rear surface of the square frame body 6a in longitudinal direction, and thereon are fixed a plurality of interfitting members 20 which are guided by the rail members 5 and 5. Moreover, the rail member 7 for front and back sides is mounted fixedly onto the upper surface of each horizontal guide frame 6b, and a horizontal level steel plate 21b connects side surfaces of the horizontal guide frames 6b and 6b. The concrete "k" is filled sealingly into the horizontal guide frames 6b and 6b. In this case, the concrete "k" may be filled over the full or partial length of the horizontal guide frames 6b and 6b. The concrete "k" increases rigidity and mass around the horizontal guide frames 6b and 6b that easily vibrate by weight of the spindle head 8. The concrete "k" is contained in airtight, thereby preventing water evaporating. Therefore, the concrete "k" is prevented the aged deterioration due to touching with the air like the above. A bulging member 23 is provided upwardly oblique back on one side of the upper surface of the upper lateral prismatic body 22 of the square frame body 6a, and an open ring nut supporting member 24 is fixed on the tip of the bulging member 23. The lateral screw axis 18 is screwed into a nut body 25 that is clamped by the nut supporting member 24. Besides, a vertical supporting plate 26 is secured between rear ends of the right and left horizontal guide frames 6b, 6b, and a servomotor 27 is fixed on the rear surface of the supporting plate 26 to displace the spindle head 8 in longitudinal direction f3. The spindle head 8 is provided with a head frame 29 that supports free-rotatively a spindle 28 for front and back sides. Besides, a not-illustrated servomotor is provided inside the head frame 29 to rotate the spindle 28, and a plurality of interfitting members 30 are provided on the lower surface of the head frame 29 so as to be guided by the rail members 7. A not-illustrated screw-nut mechanism is provided between the head frame 29 and the servomotor 27 to displace the head frame 29 in longitudinal direction by rotations of the servomotor 27. In order to form a machining center based on the above characteristics, the following not-illustrated components are added. That is, an automatic tool changer is provided to receive a tool magazine storing many tools or tools of the tool magazine and to insert tightly them into the tip of the spindle 28, or conversely to extract them from the tip of the spindle 28 and to put back them into the tool magazine. Besides, an enclosure is provided at need to cover the whole components on the bed 1. Next, an explanation follows about operations of the above characteristics. The first saddle 4 is displaced in the vertical direction f1 by rotations of the servomotor 11, the second saddle 6 in the lateral direction f2 by the servomotor 16, and the spindle head 8 in the longitudinal direction f3 by the servomotor 27, respectively. Therefore, the spindle 28 is displaced on an optional position of three-axis directions. Hence, a workpiece fixed on the not-illustrated work-table can be machined by means of displacement of the spindle 28 and rotations by the tool drive motor that is attached on the tip of the spindle 28. Since the first saddle 4 increases rigidity and mass by the concrete "k" filled therein, it hardly vibrates, thereby reducing vibrations of the second saddle 6 and the spindle head 8 and the like to enable a high-precision machining. Besides, since the first saddle 4 is mainly composed of the square frame body, the spindle head 8 can be assembled into the square hole "b", thereby compacting the size of the whole machine tool, as well as the vertical length supported by the column 2 is enlarged, thereby stabilizing the supporting force by the front surface of the column 2. Besides, since the horizontal guide frames 6b and 6b of the second saddle 6 increase rigidity and mass by the concrete "k" filled therein as well as the first saddle 4, they hardly vibrate, thereby reducing directly vibrations of the spindle head 8 to enable a high-precision machining. Since the second saddle 6 comprises the square frame body 6a and the horizontal guide frames 6b and 6b, the spindle head 8 can be disposed inside the square hole "c" of the square frame body 6a, thereby assembling compactly the spindle head 8, as well as the guided length of the spindle head 8 in the longitudinal direction f3 is enlarged, thereby increasing the stability of the spindle head 8 to a moment in the longitudinal direction f3 and the moving range of the spindle head 8 in the longitudinal direction f3. Moreover, since in the second saddle 6 the concrete "k" is filled into only the horizontal guide frames 6b and 6b, rigidity and mass necessary for the second saddle 6 can be obtained by a little concrete "k". Besides, since the horizontal guide frame 6b is provided to every rail member 7 and is filled with the concrete "k", the rigidity and the mass of the second saddle 6 can be obtained more rationally.

Claims: A machine tool, comprising: a bed (1); a column (2) of a rectangular frame body forming a large space to its central inside, mounted standingly onto one side of said bed (1) so as to dispose the space to a front side; a pair of guide rails (3, 3) mounted on a front surface of said column (2); a first saddle (4) of a square frame body whose upper and lower side members (4b, 4c) are made of prismatic bodies of rectangular cross-section mounted movably in vertical direction (f1); a second saddle (6) forming a square frame body (6a) and driven by a servomotor (16); a pair of right and left square cylindrical members (6b, 6b) of rectangular cross-section mounted on a lower rear surface of the square frame body (6a) in horizontal direction (f3) in a specified length and crossing the rear surface of the square frame body (6a) at a right angle; rail members (5) laid on the upper and lowerside members (4b, 4c) of the first saddle (4), respectively; and rail members (7) laid on the square cylindrical members (6b, 6b) of the second saddle (6), respectively; characterized in that the pair of guide rails (3, 3) is a pair of right and left guide rails and is mounted on the column (2) in vertical direction; the upper and lower side members (4b, 4c) forming the first saddle are movably mounted through the guide rails (3, 3); the servomotor (16) drives the second saddle (6) laterally (f2) combined with a lateral screw axis (18) provided on an upper surface of an upper side member (4b) of the first saddle (4); the square frame body (6a) formed by the second saddle is smaller in size than the first saddle; a bulging member (23) is provided on an upper surface of the square frame body (6a), and screwed on the lateral screw axis (18) to displace the second saddle in lateral directiow(f2); and of the moving elements concrete (k) is filled sealing only into the prismatic bodies of the upper lower side members (4b, 4c) and into the pair of right and left square cylindrical members (6b, 6b).

Inventors: SEO YOSHIHIDE, SUGATA SHINSUKE, SEO, YOSHIHIDE, SUGATA, SHINSUKE
Applicants: HORKOS CORP
Application year: 2000
Main classification: B23Q1
IPC codes: B23Q1, B23Q11, B23B17, F16F15