Spindle device, swing head and machine tool

Abstract

The utility model provides a main shaft device, a swing head and a machine tool. The main shaft device comprises a seat body, a mounting cylinder, a driving part and a rotating shaft, the mounting cylinder is fixedly arranged on the seat body, the mounting cylinder and the seat body are coaxially arranged, and the mounting cylinder is provided with a mounting space penetrating along the axis; the rotating shaft is rotatably arranged in the mounting space, the driving piece is arranged between the mounting cylinder and the rotating shaft, and the driving piece is used for driving the rotating shaft to rotate along the axis; the seat body is a carbon fiber seat body, the mounting cylinder is a carbon fiber cylinder body, and the carbon fiber seat body and the carbon fiber cylinder body are integrally formed. According to the main shaft device provided by the technical scheme of the utility model, the motion inertia of the main shaft device in the swinging head can be reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to processing equipment technical field especially, a kind of spindle device, swing head and machine tool. BACKGROUND

[0002] The existing five-axis machine tool direct-drive double swing head is usually made of ordinary steel material, which has high strength and rigidity. The spindle needs to withstand huge torque, bending moment and complex alternating stress during equipment operation. The spindle steel material has high yield strength and tensile strength, which can maintain the integrity of the structure under heavy load, and is not prone to deformation or fracture. For example, in the application of spindle in large machine tools, the workpiece weighing several tons is driven to rotate at high speed for machining. The high-strength characteristics of the spindle steel ensure the stable operation of the machine tool under long-time and high-load operation, and ensure the machining accuracy and efficiency.

[0003] However, the steel material has high density, resulting in a large overall weight of the double swing head (see patent No. CN208409375U), which increases the machine tool inertia, affecting the dynamic response speed and machining accuracy.

[0004] Therefore, how to reduce the inertia of the spindle device in the swing head is a problem to be solved. SUMMARY

[0005] The utility model provides a kind of spindle device, swing head and machine tool, which can reduce the inertia of the spindle device in the swing head.

[0006] The utility model provides a kind of spindle device in the first aspect, including seat body, installation cylinder, driving part and rotating shaft, the installation cylinder is fixedly arranged on seat body, the installation cylinder is coaxially arranged with the seat body and has installation space along the axis through;The rotating shaft is rotatably arranged in the installation space, the driving part is arranged between the installation cylinder and the rotating shaft, and the driving part is used to drive the rotating shaft to rotate along the axis;

[0007] The seat body is a carbon fiber seat body, the installation cylinder is a carbon fiber cylinder body, and the carbon fiber seat body and the carbon fiber cylinder body are integrally formed.

[0008] In some feasible embodiments, a bearing seat is further included, which is fixed to one end of the installation cylinder away from the seat body, and one end of the rotating shaft away from the seat body is installed in the bearing seat through a bearing. The diameter of the installation cylinder is greater than or equal to the diameter of the bearing seat.

[0009] In some feasible embodiments, the installation cylinder and the bearing seat are fixedly connected through a first fastener and structural adhesive, and the fastening direction of the first fastener is parallel to the axis.

[0010] In some possible implementations, the mounting cylinder is provided with a locking hole near one end of the bearing seat, the locking hole is threadedly connected with the first fastener, and a metal layer is arranged on the hole wall of the locking hole; and / or,

[0011] The rotating shaft is mounted in the bearing seat through the two bearings, and the two bearings are arranged side by side along the axis.

[0012] In some possible implementations, an end cover is further arranged on the side, away from the mounting cylinder, of the bearing seat, the end cover is fixedly connected with the bearing seat through a second fastener, and the fastening direction of the second fastener is parallel to the axis.

[0013] In some possible implementations, at least one of the mounting cylinder, the driving member or the space between the mounting cylinder and the driving member is provided with a flow channel for flowing of cooling liquid or cooling gas.

[0014] The driving member comprises a stator and a rotor arranged on the inner wall of the stator, and the rotor is fixedly connected with the rotating shaft through a connecting member.

[0015] In some possible implementations, the mounting cylinder is provided with a flow channel, the mounting cylinder comprises an inner cylinder, an outer cylinder fixedly sleeved on the outer wall of the inner cylinder and a sealing member arranged between the outer cylinder and the inner cylinder, the flow channel is arranged on the side of the inner cylinder, facing the outer cylinder, and the cross section of the flow channel is rectangular; the inner cylinder and the outer cylinder are fixedly connected through a third fastener and structural glue; and the sealing member is arranged on both sides of the flow channel in the extending direction.

[0016] In some possible implementations, the flow channel comprises a first sub-flow channel surrounding the outer wall of the inner cylinder and close to the seat body and a second sub-flow channel surrounding the outer wall of the inner cylinder and away from the seat body, the first sub-flow channel and the second sub-flow channel are in communication with each other, the average spiral interval of the first sub-flow channel is smaller than that of the second sub-flow channel, or the average cross section area of the first sub-flow channel is larger than that of the second sub-flow channel.

[0017] The utility model discloses a second aspect provides a swing head, including saddle and set up on the saddle of the above -mentioned main shaft device, the main shaft device sets up in the bottom of the saddle, and part structure of the main shaft device is exposed to the outside world from the inside of the saddle.

[0018] The utility model discloses a third aspect provides a machine tool, including saddle and the above -mentioned main shaft device, the main shaft device sets up in the bottom of the saddle, and part structure of the main shaft device is exposed to the outside world from the inside of the saddle, or,

[0019] Including base and the above -mentioned swing head, the swing head sets up on the base.

[0020] The main shaft device is characterized in that: a seat body, a mounting cylinder, a driving element and a rotating shaft are arranged, the mounting cylinder is fixedly arranged on the seat body, the mounting cylinder is coaxially arranged with the seat body and has a mounting space penetrating along the axis, the rotating shaft is rotatably arranged in the mounting space, the driving element is arranged between the mounting cylinder and the rotating shaft, and the driving element is used for driving the rotating shaft to rotate along the axis; the seat body is a carbon fiber seat body, the mounting cylinder is a carbon fiber cylinder body, and the carbon fiber seat body and the carbon fiber cylinder body are integrally formed; compared with the metal material of the existing seat body and mounting cylinder, the weight of the main shaft device can be reduced, the rigidity of the main shaft device can be ensured, a driving element with smaller power and volume can be selected, and the compactness of the main shaft device is improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiment or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained according to the structures shown in these drawings without creative labor.

[0022] Figure 1 The schematic diagram of the main shaft device provided by an embodiment of the present application.

[0023] Figure 2 The sectional view of the main shaft device provided by an embodiment of the present application.

[0024] Figure 3 The assembly schematic diagram of the main shaft device and the ram in the machine tool provided by an embodiment of the present application.

[0025] Element symbol explanation

[0026] 100, seat body; 200, mounting cylinder; 210, inner cylinder; 220, outer cylinder; 230, sealing element; 300, driving element; 310, stator; 320, rotor; 330, connecting element; 400, rotating shaft; Z, axis; J, radial direction; S, mounting space; 500, bearing seat; L, flow channel; L1, first sub-flow channel; L2, second sub-flow channel; 600, ram; 700, end cover; R1, bearing; R2, bidirectional bearing; J1, first fastener; J2, second fastener.

[0027] The implementation, functional characteristics and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0028] In the description of the utility model, it is understood that the directions or positional relations indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the directions or positional relations shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and thus cannot be understood as indicating or implying that the devices or elements indicated must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as limiting the utility model.

[0029] In addition, the terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the utility model, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0030] In the utility model, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For ordinary skilled persons in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0031] In order to have a clearer and more accurate understanding of the content of the utility model, the drawings will be described in detail. The drawings of the specification show examples of embodiments of the utility model, wherein the same reference numerals represent the same elements. It can be understood that the proportions shown in the drawings of the specification are not the proportions actually implemented in the utility model, which are only for the purpose of illustration, and are not drawn according to the original size.

[0032] Please refer to Figure 1 and 2 , the utility model provides a kind of main shaft device, including seat body 100, installation cylinder 200, driving piece 300 and rotating shaft 400.

[0033] Please refer to Figure 2 , seat body 100 and installation cylinder 200 are used to support driving piece 300 and rotating shaft 400. In the embodiment, the installation cylinder 200 is fixedly arranged on the seat body 100, the installation cylinder 200 is coaxially arranged with the seat body 100 and has installation space S through along axis Z. It can be understood that the diameter of the seat body 100 on the side close to the installation cylinder 200 along the axis Z can be less than the diameter of the seat body 100 on the side away from the installation cylinder 200 along the axis Z.

[0034] The rotating shaft 400 is rotatably arranged in the mounting space S, and the end of the rotating shaft 400 away from the mounting cylinder 200 is a clamping end for clamping a tool. The diameter of the clamping end is greater than the diameter of the end of the rotating shaft 400 away from the seat body 100. Therefore, the clamping end is rotatably arranged on the side of the seat body 100 away from the mounting cylinder 200 through the bidirectional bearing R2. The bidirectional bearing R2 can provide support in the axial direction and the radial direction J, thereby ensuring the support between the rotating shaft 400 and the seat body 100 in the axial direction and the radial direction J.

[0035] Please refer to Figure 2 The mounting cylinder 200 is used for mounting the driving member 300. The mounting cylinder 200 is a carbon fiber cylinder body, the seat body 100 is a carbon fiber seat body 100, and the carbon fiber seat body 100 and the carbon fiber cylinder body are integrally formed. Compared with the existing seat body 100 and mounting cylinder 200 made of metal material, the weight of the spindle device can be reduced, the rigidity of the spindle device can be ensured, the driving member 300 with smaller power and volume can be selected, and the compactness of the spindle device can be improved.

[0036] Please refer to Figure 2 The specific structure of the mounting cylinder 200 will be introduced below. The mounting cylinder 200 is provided with a flow channel L. By arranging the flow channel L, the mounting cylinder 200 can be cooled down. The mounting cylinder 200 is connected with the driving member 300, thereby cooling the driving member 300. The position of the flow channel L and the structure design of the flow channel L are described in detail below. In this embodiment, the mounting cylinder 200 includes an inner cylinder 210, an outer cylinder 220 fixedly sleeved on the outer periphery of the inner cylinder 210, and a sealing member 230 located between the outer cylinder 220 and the inner cylinder 210. The flow channel L is arranged on the side of the inner cylinder 210 facing the outer cylinder 220. The cross section of the flow channel L is rectangular. The inner cylinder 210 and the outer cylinder 220 are fixedly connected through a third fastener and structural glue. The sealing member 230 is arranged on both sides of the flow channel L in the extending direction.

[0037] Please refer to Figure 2 The rigidity of the structure provided with the flow channel L is reduced. Therefore, according to the actual situation, the flow channel L for flowing cooling liquid or cooling gas can be arranged on at least one of the mounting cylinder 200, the driving member 300, and the mounting cylinder 200 and the driving member 300. When the driving member 300 generates a large amount of heat, the flow channel L is arranged on the mounting cylinder 200, the driving member 300, and the mounting cylinder 200 and the driving member 300. When the driving member 300 generates a small amount of heat, the flow channel L can be arranged on any one of the mounting cylinder 200, the driving member 300, and the mounting cylinder 200 and the driving member 300, thereby making the design of the flow channel L more flexible.

[0038] Please refer to Figure 2 , the following describes the design of the flow channel L on the mounting cylinder 200, the temperature of the driving member 300 at different positions along the axis Z is different, so that the design of the flow channel L on the mounting cylinder 200 can match the non-uniform heat source on the driving member 300, the flow channel L includes a first sub-flow channel L1 surrounding the outer periphery of the inner cylinder 210 and close to the seat body 100, and a second sub-flow channel L2 surrounding the outer periphery of the inner cylinder 210 and away from the seat body 100, the first sub-flow channel L1 and the second sub-flow channel L2 are in communication with each other, the average helical interval of the first sub-flow channel L1 is smaller than that of the second sub-flow channel L2, or the average cross-sectional area of the first sub-flow channel L1 is larger than that of the second sub-flow channel L2, it can be understood that the position of the driving member 300 along the axis Z which generates more heat corresponds to the position of the first sub-flow channel L1, and the heat dissipation capacity of the first sub-flow channel L1 is stronger than that of the second sub-flow channel L2, so the position of the driving member 300 which generates more heat corresponds to the position of the first sub-flow channel L1, thereby reasonably designing the flow channel L, ensuring the rigidity of the mounting cylinder 200 while achieving heat dissipation of the driving member 300.

[0039] Please refer to Figure 2 , the following describes the specific structure of the driving member 300, the driving member 300 is arranged between the mounting cylinder 200 and the rotating shaft 400, the driving member 300 is used to drive the rotating shaft 400 to rotate along the axis Z, the driving member 300 includes a stator 310 and a rotor 320 arranged on the inner periphery of the stator 310, and the rotor 320 is fixedly connected with the rotating shaft 400 through a connecting member 330. In this embodiment, the stator 310 is in a cylindrical shape, the rotor 320 is also in a cylindrical shape, and the stator 310 is located on the outer periphery of the rotor 320. The connecting member 330 is located at one end of the mounting cylinder 200 close to the seat body 100 along the axis Z, and the connecting member 330 includes an inner ring and an outer ring which are integrally formed, the bottom of the inner ring is flush with the bottom of the outer ring in the radial direction J, wherein the radial direction J is perpendicular to the axis Z in the horizontal direction, and the top of the inner ring is higher than the top of the outer ring. The rotating shaft 400 is provided with a mounting step, the inner ring of the connecting member 330 is locked with the mounting step of the rotating shaft 400 along the axis Z, and the outer ring of the connecting member 330 is locked with one end of the rotor 320 close to the seat body 100 along the axis Z.

[0040] Please refer to Figure 2In order to ensure that the rotating shaft 400 rotates stably in the installation space S, the main shaft device further comprises a bearing seat 500 fixed to the end of the installation cylinder 200 away from the seat body 100, the bearing seat 500 can be annular, and the end of the rotating shaft 400 away from the seat body 100 is installed in the bearing seat 500 through a bearing R1; the diameter of the installation cylinder 200 is greater than or equal to the diameter of the bearing seat 500. Since the rotating shaft 400 has a certain length along the axis Z, by increasing the bearing seat 500, the bearing seat 500 and the seat body 100 are located at both ends of the installation cylinder 200 along the axis Z respectively, the seat body 100 is connected with one end of the rotating shaft 400 through the bearing R1, and the bearing seat 500 is connected with the other end of the rotating shaft 400 through the bearing R1, both ends of the rotating shaft 400 are rotatably connected with the bearing seat 500 and the seat body 100 through at least one bearing R1 respectively, for example, the rotating shaft 400 is installed in the bearing seat 500 through two bearings R1, the two bearings R1 are arranged side by side along the axis Z, and the bearing R1 can at least provide rolling support force in the radial direction J, and the bearing R1 can also provide rolling support force in the radial direction J and the axial direction Z at the same time, thereby improving the stability of the rotating shaft 400 rotating relative to the seat body 100, the installation cylinder 200 and the bearing seat 500.

[0041] Please refer to Figure 2 In the selection of the fastening scheme of the installation cylinder 200 and the bearing seat 500, since the material of the installation cylinder 200 is carbon fiber, as few holes as possible are opened on the installation cylinder 200, in the embodiment, the installation cylinder 200 and the bearing seat 500 are fixedly connected through a first fastener J1 and structural glue, the fastening direction of the first fastener J1 is parallel to the axis Z, and the structural glue is arranged between the installation cylinder 200 and the bearing seat 500 along the axis Z.

[0042] The material of the mounting cylinder 200 is carbon fiber, which is brittle. When drilling or opening holes, stress concentration is easily generated around the holes, resulting in delamination or cracking. When the first fastener J1 is locked with the mounting cylinder 200, the mounting cylinder 200 made of carbon fiber is broken. In order to avoid the breakage of the mounting cylinder 200, specifically, a locking hole is arranged at one end of the mounting cylinder 200 close to the bearing seat 500, which is threadedly connected with the first fastener J1. The hole wall of the locking hole is provided with a metal layer. When the hole wall of the locking hole is not provided with a metal layer, the metal layer can disperse stress and improve the strength and durability of the connection part. In some other embodiments, an epoxy glue can be coated and pressed into a metal ring. It can be understood that the number of the first fasteners J1 can be two, which can reduce the number of holes opened on the mounting cylinder 200 as much as possible. When the hole wall of the locking hole is provided with a metal layer, the number of the first fasteners J1 can be at least three. Since the metal layer is protected, the connection between the mounting cylinder 200 and the bearing seat 500 can be fastened, and the breakage of the first fastener J1 when locked with the mounting cylinder 200 can be avoided.

[0043] Please refer to Figure 2 In order to avoid dust, cutting fluid and mist from the outside into the bearing seat 500 and the mounting cylinder 200, the spindle device further comprises an end cover 700 arranged on the side of the bearing seat 500 away from the mounting cylinder 200. The end cover 700 is fixedly connected with the bearing seat 500 through a second fastener J2. The fastening direction of the second fastener J2 is parallel to the axis Z. The end cover 700 plays a protective role. The end cover 700 comprises an inner ring body and an outer cylinder body. The cross section of the end cover 700 is L-shaped. The inner ring body of the end cover 700 and the rotating shaft 400 can be provided with a labyrinth structure.

[0044] The above-mentioned spindle device is provided with a seat body 100, a mounting cylinder 200, a driving member 300 and a rotating shaft 400. The mounting cylinder 200 is fixedly arranged on the seat body 100. The mounting cylinder 200 and the seat body 100 are coaxially arranged and have a mounting space S penetrating along the axis Z. The rotating shaft 400 is rotatably arranged in the mounting space S. The driving member 300 is arranged between the mounting cylinder 200 and the rotating shaft 400. The driving member 300 is used to drive the rotating shaft 400 to rotate along the axis Z. The seat body 100 is a carbon fiber seat body 100. The mounting cylinder 200 is a carbon fiber cylinder body. The carbon fiber seat body 100 and the carbon fiber cylinder body are integrally formed. The material of the existing seat body 100 and mounting cylinder 200 is metal material. The weight of the spindle device can be reduced, the rigidity of the spindle device can be ensured, and a driving member 300 with smaller power and volume can be selected, so that the compactness of the spindle device is improved.

[0045] Please refer toFigure 2 and 3 The utility model discloses a third aspect provides a machine tool, including the saddle 600 and above -mentioned main shaft device, the main shaft device sets up the bottom of the saddle 600, and the partial structure of the main shaft device is exposed to the outside world from the inside of the saddle 600, or,

[0046] The utility model discloses a third aspect provides a machine tool, including the saddle 600 and above -mentioned main shaft device, the main shaft device sets up the bottom of the saddle 600, and the partial structure of the main shaft device is exposed to the outside world from the inside of the saddle 600, or,

[0047] Including the base and above -mentioned swing head, the swing head sets up on the base.

[0048] Obviously, those skilled in the art can make various modifications and variations to the utility model without departing from the spirit and scope of the utility model. Thus, if these modifications and variations of the utility model fall within the scope of the claims of the utility model and their equivalents, the utility model also intends to include these modifications and variations.

[0049] The above-mentioned is only the preferred embodiment of the utility model, and certainly can not be used to limit the right scope of the utility model, therefore the equivalent change of the utility model claim is still within the range that the utility model covers.

Claims

1. A spindle device, comprising a base (100), a mounting cylinder (200), a driving member (300), and a rotating shaft (400), wherein the mounting cylinder (200) is fixedly disposed on the base (100), the mounting cylinder (200) is coaxially disposed with the base (100) and has a mounting space (S) extending along an axis (Z); the rotating shaft (400) is rotatably disposed within the mounting space (S), and the driving member (300) is disposed between the mounting cylinder (200) and the rotating shaft (400), the driving member (300) being used to drive the rotating shaft (400) to rotate along the axis (Z); characterized in that, The base (100) is a carbon fiber base, and the mounting cylinder (200) is a carbon fiber cylinder, and the carbon fiber base and the carbon fiber cylinder are integrally formed.

2. The spindle device as described in claim 1, characterized in that, It also includes a bearing housing (500), which is fixed to the end of the mounting cylinder (200) away from the seat body (100), and the end of the rotating shaft (400) away from the seat body (100) is mounted in the bearing housing (500) through a bearing (R1); the diameter of the mounting cylinder (200) is greater than or equal to the diameter of the bearing housing (500).

3. The spindle device as described in claim 2, characterized in that, The mounting cylinder (200) and the bearing seat (500) are fixedly connected by a first fastener (J1) and structural adhesive. The fastening direction of the first fastener (J1) is parallel to the axis (Z).

4. The spindle device as described in claim 3, characterized in that, The mounting cylinder (200) has a locking hole at one end near the bearing housing (500), the locking hole being threaded into the first fastener (J1), and the peripheral wall of the locking hole being provided with a metal layer; and / or, The rotating shaft (400) is mounted in the bearing housing (500) by two bearings (R1), which are arranged side by side along the axis (Z).

5. The spindle assembly as described in claim 2, characterized in that, It also includes an end cap (700), which is disposed on the side of the bearing housing (500) away from the mounting cylinder (200). The end cap (700) is fixedly connected to the bearing housing (500) by a second fastener (J2), and the fastening direction of the second fastener (J2) is parallel to the axis (Z).

6. The spindle assembly as described in any one of claims 1-5, characterized in that, At least one of the three components—the mounting cylinder (200), the driving member (300), or the mounting cylinder (200) and the driving member (300)—is provided with a flow channel (L) for the flow of coolant or cooling gas. The drive unit (300) includes a stator (310) and a rotor (320) disposed on the inner circumference of the stator (310). The rotor (320) is fixedly connected to the rotating shaft (400) by a connector (330).

7. The spindle assembly as described in claim 6, characterized in that, The mounting cylinder (200) is provided with a flow channel (L). The mounting cylinder (200) includes an inner cylinder (210), an outer cylinder (220) fixedly sleeved on the outer periphery of the inner cylinder (210), and a sealing element (230) located between the outer cylinder (220) and the inner cylinder (210). The flow channel (L) is located on the side of the inner cylinder (210) facing the outer cylinder (220), and the cross-section of the flow channel (L) is rectangular. The inner cylinder (210) and the outer cylinder (220) are fixedly connected by a third fastener and structural adhesive. The sealing element (230) is provided on both sides along the extension direction of the flow channel (L).

8. The spindle assembly as described in claim 7, characterized in that, The flow channel (L) includes a first sub-flow channel (L1) surrounding the outer periphery of the inner cylinder (210) and close to the seat (100), and a second sub-flow channel (L2) surrounding the outer periphery of the inner cylinder (210) and away from the seat (100). The first sub-flow channel (L1) and the second sub-flow channel (L2) are interconnected. The average spiral interval of the first sub-flow channel (L1) is smaller than the average spiral interval of the second sub-flow channel (L2), or the average cross-sectional area of ​​the first sub-flow channel (L1) is larger than the average cross-sectional area of ​​the second sub-flow channel (L2).

9. A head-swinging mechanism, characterized in that, The device includes a slide (600) and a spindle assembly as described in any one of claims 1-8 disposed on the slide (600), the spindle assembly being disposed at the bottom of the slide (600), and a portion of the structure of the spindle assembly being exposed from the interior of the slide (600) to the outside.

10. A machine tool, characterized in that, Includes a slide (600) and a spindle assembly as described in any one of claims 1-8, the spindle assembly being disposed at the bottom of the slide (600), with a portion of the structure of the spindle assembly exposed from the interior of the slide (600) to the outside; or, It includes a base and a swing head as described in claim 9, wherein the swing head is disposed on the base.

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