Rotary joint device for air chucks

Abstract

By providing a cooling air passage in the rotary joint housing, the amount of heat generated by the rotary joint can be suppressed, enabling an increase in the rotational speed of the air chuck, as well as miniaturization and weight reduction of the rotary joint. [Solution] A rotary joint device for supplying air to an air circulation pipe 4 connected to an air chuck 2 of a machine tool, comprising a housing 22 made of a tubular body having an air supply port connected to an air source, and a sleeve 26 fixed to the air circulation pipe 4 and fitted to the inner diameter of the housing 22 via a bearing 24. An air passage 36 is formed in the pipe wall of the housing 22 by a plurality of elongated holes extending axially and grooves connecting the ends of the elongated holes. One end of the air passage 36 is connected to an air supply port for driving the air chuck, and the other end of the air passage 36 is connected to the gap between the housing 22 and the sleeve 26.

Description

Technical Field

[0001] The present invention relates to a rotary joint device provided in a path for supplying air to an air chuck used in a machine tool such as a NC machine tool.

Background Art

[0002] Diagram type and other types of air chucks used in machine tools such as NC machine tools are configured to be opened and closed (grasping and releasing of workpieces) controlled by air supplied to an internal cylinder from an air supply device (see, for example, Patent Document 1). The air chuck is configured such that its interior is connected to a pipe for air flow of an air supply device on the machine tool main body side, and air for chuck opening and closing is supplied through the pipe. A sleeve is connected to the pipe for air flow, and the sleeve is rotatably supported via a bearing by a tubular housing of a rotary joint on the main body side of the machine tool.

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0003] When holding a workpiece with an air chuck and machining the workpiece, the air chuck, the pipe for air flow, and the sleeve rotate at high speed. When the sleeve side rotates continuously, the bearing of the rotary fitting portion between the sleeve and the housing of the rotary joint generates heat, and the housing expands. As a result, the gap between the housing and the sleeve widens, and air leakage increases, and there is a problem that the rotational speed of the air chuck cannot be further increased. Further, when trying to reduce the influence of heat generation by making the housing of the rotary joint larger, there is a problem that the rotary joint structure becomes large-sized and the cost increases. An object of the present invention is to solve the above problems. [Means for solving the problem]

[0004] To achieve the above objective, the present invention provides a rotary joint device for supplying air to an air circulation pipe 4 connected to an air chuck 2 of a machine tool, comprising a housing 22 made of a tubular body having an air supply port connected to an air source, and a sleeve 26 fixed to the air circulation pipe 4 and fitted to the inner diameter portion of the housing 22 via a bearing 24, wherein an air passage 36 is formed in the pipe wall of the housing 22 by a plurality of elongated holes extending axially and grooves connecting the ends of the elongated holes, one end of the air passage 36 is connected to an air supply port for driving the air chuck, and the other end of the air passage 36 is connected to the gap between the housing 22 and the sleeve 26. Furthermore, the present invention is characterized in that the air passage 36 is formed in a zigzag pattern over a wide area on the pipe wall of the housing 22. [Effects of the Invention]

[0005] As described above, the present invention provides a cooling air passage in the rotary joint housing, thereby suppressing the amount of heat generated by the rotary joint, improving the rotational speed of the air chuck, and enabling miniaturization and weight reduction of the rotary joint. Furthermore, it reduces the amount of air leakage. [Brief explanation of the drawing]

[0006] [Figure 1] This is an explanatory diagram of the external appearance of the housing of the rotary joint device according to the present invention. [Figure 2] This is a diagram illustrating the right side of the housing. [Figure 3] This is a diagram illustrating the left side of the housing. [Figure 4] This is a diagram illustrating the exterior appearance of the housing. [Figure 5] This is an explanatory diagram showing the connection between the rotary joint and the air circulation pipe. [Figure 6]This is an explanatory diagram showing the connection between the rotary joint and the air chuck. [Modes for carrying out the invention]

[0007] The configuration of the present invention will be described in detail below with reference to the attached drawings. First, let's explain the mechanism of the air chuck. In Figure 6, 2 is a diagram-type air chuck, which is detachably fixed to the rotating part of the machine tool body (not shown) by bolts. A triple-layered air circulation pipe 4 is connected to the air chuck 2, and air for opening and closing the chuck is supplied from the rotary joint 6 via the air circulation pipe 4.

[0008] When air is supplied from the air source to the open-side air supply port 8 of the rotary joint 6, the air passes through the air passage of the air circulation pipe 4 and then reaches the air chuck 2. The air that reaches the air chuck 2 pushes the pistons 10 and 12 inside the chuck housing 3 toward the spacer 14, inflating the diaphragm 16. When the diaphragm 16 inflates, the claws 18 attached to the diaphragm 16 are displaced in the diameter expansion direction, and the air chuck 2 opens.

[0009] Furthermore, when air is supplied from an air source (not shown) to the closed-side air supply port 20 of the rotary joint 6, the air is supplied to the air chuck 2 via the air passage of the air circulation pipe 4. When air is supplied to the air chuck 2, the pistons 10 and 12 are pulled back, and the diaphragm 16 is retracted. As the diaphragm 16 is retracted, the claws 18 are displaced in the diameter reduction direction, and the air chuck 2 opens.

[0010] The rotary joint 6 includes a tubular housing 22 fixed to the machine tool body, and the outer surface of a sleeve 26, which is fitted and fixed to the pipe 4, is rotatably fitted to the inner surface of the housing 22 via a bearing 24. Pipe 4 has a triple-pipe structure, with two air passages formed between each pipe. One air passage communicates with the open-side air supply port 8, and the other air passage communicates with the closed-side air supply port 20. As shown in Figure 5, a front cap 30 is screw-fastened to one side of the housing 22 via a sealing packing 28. An end cap 34 is bolted to the other side of the housing 22 via a sealing packing 32.

[0011] Figure 1 shows the cooling air passage 36 formed in the housing 22. The air passage 36 is formed by drilling multiple elongated holes a to i along the axial direction in the pipe wall of the housing 22. The left ends of elongated holes h and i are connected by groove A, the left ends of elongated holes a and b are connected by groove B, the left ends of elongated holes c and d are connected by groove C, and the left ends of elongated holes e and f are connected by groove D. The right ends of elongated holes g and e are connected by groove E, the right ends of elongated holes e and d are connected by groove F, the right ends of elongated holes b and c are connected by groove G, and the right end of elongated hole ai is connected by groove H. These elongated holes a to h and grooves A to H form a zigzag air passage 36 over the entire pipe wall of the housing 22.

[0012] Grooves A to H formed in the pipe wall of the housing 22 are closed by sealing packings 32 and 28. The starting end of the air passage 36 communicates with a closed-side air supply port 20 formed by a joint 38, and air for driving the chuck is supplied to the air passage 36 through this air supply port 20. A connector 40 is provided on the pipe wall of the housing 22, the pipe portion of the connector 40 communicates with the end of the air passage 36, and the end 40a of the connector 40 opens to the inner circumferential surface of the housing 22.

[0013] In this configuration, the cooling air supplied to the air passage 36 is injected through the pipe portion of the connector 40 into the small gap between the housing 22 and the sleeve 26, causing a small amount of air to leak out of the air passage 36 through this gap. In addition, in this embodiment, the start end of the air flow path 36 is configured to communicate with the closed-side air supply port 20. However, the configuration is not particularly limited to this, and the start end of the air flow path 36 may be configured to communicate with the open-side air supply port 8.

Explanation of Signs

[0014] 2 Air chuck 3 Chuck housing 4 Air flow pipe 6 Rotary joint 8 Open-side air supply port 10 Piston 12 Piston 14 Spacer 16 Diagram 18 Claw 20 Closed-side air supply port 22 Housing 24 Bearing 26 Sleeve 28 Sealing packing 30 Front cap 32 Sealing packing 34 End packing 36 Air flow path 38 Joint 40 Connector a~i Long hole A~H Groove

Claims

1. A rotary joint device for supplying air to an air circulation pipe 4 connected to an air chuck 2 of a machine tool, comprising a housing 22 made of a tubular body having an air supply port connected to an air source, and a sleeve 26 fixed to the air circulation pipe 4 and fitted to the inner diameter of the housing 22 via a bearing 24, wherein an air passage 36 is formed in the pipe wall of the housing 22 by a plurality of elongated holes extending axially and grooves connecting the ends of the elongated holes, one end of the air passage 36 is connected to an air supply port for driving the air chuck, and the other end of the air passage 36 is connected to the gap between the housing 22 and the sleeve 26.

2. A rotary joint device for an air chuck, characterized in that the air passage 36 is formed in a zigzag pattern over a wide area on the pipe wall of the housing 22.

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