Note: Descriptions are shown in the official language in which they were submitted.
RIVETING TOOL FOR HIGH-STRENGTH RING
GROOVE RIVET
Technical Field
The present utility model belongs to the technical field of riveting and
fastening, particularly to the technical field of handheld cordless electric
tool
design and production, and especially relates to a riveting tool for a high-
strength ring groove rivet.
Background
Ring groove rivets are widely used in fields such as new energy, bridges,
and steel structures. If hydraulic or pneumatic tools are used, they are
limited
by on-site operating conditions, such as high altitude and high-voltage power
supply. These tools are often difficult to meet the working conditions. If
cordless charging electric riveting tools can be used for installation, these
problems can be better solved. Currently, the output tension of electric
riveting
tools at home and abroad is below 301N, which cannot meet the installation
requirements of large diameter ring groove rivets.
Summary
The present utility model discloses a riveting tool for a high-strength ring
groove rivet according to the defects of the prior art. The present utility
model
provides a riveting tool that can overcome the defects of existing riveting
tools
in riveting high-strength ring groove rivets, and adopts a movable electric
drive,
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with a maximum riveting force of 701N, and can control different riveting
methods.
The present utility model is implemented by the following technical
solution:
A riveting tool for a high-strength ring groove rivet, comprising a gun
head assembly, a driving mechanism, a transmission mechanism, a power
source and a control module which are arranged in a riveting tool shell,
wherein the gun head assembly comprises a clamping jaw and an anvil
for squeezed riveting of a ring groove rivet;
the power source is a detachable and rechargeable battery;
the driving mechanism comprises a DC motor, a reduction gearbox driven
by the motor, and a driving shaft;
the transmission mechanism is a planetary roller lead screw transmission
mechanism, a planetary roller lead screw shaft of the planetary roller lead
screw transmission mechanism is in coaxial driving connection with the
clamping jaw of the gun head assembly, and the planetary roller lead screw
shaft is in driving connection with the driving shaft of the driving mechanism
through gears installed on the planetary roller lead screw shaft and the
driving
shaft of the driving mechanism respectively.
Furthermore, the planetary roller lead screw shaft is driven parallel to the
driving shaft.
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Furthermore, the transmission mechanism further comprises a planetary
roller lead screw nut which is in driving fit with the planetary roller lead
screw
shaft, and a large gear is sleeved on the periphery of the planetary roller
lead
screw nut; the diameter of a pinion sleeved on the driving shaft of the
driving
mechanism is smaller than that of a large gear, and the pinion sleeved on the
driving shaft is in driving connection with the large gear sleeved on the
planetary roller lead screw nut.
Furthermore, a planar thrust roller bearing is arranged on a front end face
of the planetary roller lead screw nut, a needle roller thrust bearing is
arranged
on a rear end face, and a set of needle roller bearings is arranged before and
behind the periphery respectively.
A set of needle roller bearings is arranged before and behind the periphery
of the driving shaft respectively.
The control module of the present utility model comprises: an STM32
main controller circuit, a current sampling circuit, a brushless DC motor
drive
circuit, a Hall stroke protection circuit, an overcurrent protection circuit,
a Hall
limit circuit, and a blocking protection circuit.
For the riveting tool of the present utility model, the output tension can
reach 701N, and riveting installation of ring groove rivets with the diameter
specification of 12mm can be effectively completed; the present utility model
is provided with a man-machine interaction interface, so that riveting
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installation modes can be selected according to rivets of different
specifications
and models; The torque of the motor can be controlled by adjusting the input
current of the motor, and finally the output tension of the tool is adjusted.
The drive and its transmission structure of the present utility model adopt
the planetary roller lead screw as a component for converting rotary motion
into linear motion; the planetary roller lead screw is used in design of
handheld
lithium battery riveting tools, and the riveting force is adjusted using a
current
control program. Compared to the ball screw used in conventional electric
tools,
the planetary roller lead screw shaft is in line contact with the lead screw
nut,
while the ball screw shaft is in point contact with the lead screw nut. Line
contact has better stress than point contact. For two types of lead screws
with
the same diameter specification, the planetary roller lead screw can
theoretically achieve three times the load capacity and six times the service
life
of ordinary ball screws. So, in the design of high tension electric riveting
tools,
using planetary roller lead screws with smaller diameter specifications can
meet the design requirements and effectively reduce the weight of the entire
machine.
Brief Description of the Drawings
Fig. 1 is a structural diagram of the riveting tool of the present utility
model;
Fig. 2 is a partially enlarged schematic diagram of Fig. 1;
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Figs. 3 to 6 are schematic diagrams of the process of riveting a short tail
type ring groove rivet;
Figs. 7 to 10 are schematic diagrams of the process of riveting a
breakaway type ring groove rivet.
In the figure, 1-clamping jaw, 2-anvil, 3-outer sleeve, 4-connecting shaft,
5-left end cover, 6-base, 7-steel ring, 8-needle roller bearing, 9-large gear,
10-
needle roller bearing, 11-right end cover, 12-needle roller thrust bearing, 13-
motor drive circuit board, 14-cooling fan, 15-steel ring, 16-LCD screen, 17-
key, 18-motor, 19-control circuit board, 20-lithium battery, 21-switch, 22-
reduction gearbox, 23-button battery, 24-pinion, 25-LED light, 26-needle
roller
bearing, 27-planetary roller lead screw nut, 28-planar thrust roller bearing,
29-
planetary roller lead screw shaft, F-tension.
Detailed Description of the Preferred Embodiments
The present utility model will be further described below in conjunction
with the detailed description. The detailed description is a further
explanation
of the principle of the present utility model, and does not limit the present
utility model in any way. The same or similar technology as the present
utility
model does not exceed the scope of protection of the present utility model.
Refer to the figures.
The riveting tool for a high-strength ring groove rivet in the present utility
model is driven by its own battery, comprising a gun head assembly, a driving
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mechanism, a transmission mechanism, a power source, etc.
The gun head assembly comprises a clamping jaw 1 and an anvil 2; the
anvil 2 is fixed with a gun body outer sleeve 3, and the clamping jaw 1 is in
transmission connection with the transmission mechanism. The power source
can be provided by a rechargeable lithium battery 20.
The driving mechanism is a reduction motor 18 driven by the rechargeable
lithium battery 20. The transmission mechanism is a planetary roller lead
screw
transmission mechanism. The reduction motor 18 drives the planetary roller
lead screw nut 27 to rotate through gear transmission, resulting in axial
linear
motion of the planetary roller lead screw shaft 29 to generate tension or
thrust.
The present utility model adopts the planetary roller lead screw as a
component for converting rotary motion into linear motion; the planetary
roller
lead screw is used in design of handheld lithium battery riveting tools, and
the
riveting force is adjusted using a current control program.
Compared to the ball screw drive used in electric tools, the ball screw and
lead screw nut are in point contact; in the riveting tool of the present
utility
model, the planetary roller lead screw shaft 29 is in line contact with the
lead
screw nut 27, and line contact has better stress than point contact; for two
types
of lead screws with the same diameter specification, the planetary roller lead
screw can theoretically achieve three times the load capacity and six times
the
service life of ordinary ball screws. In the design of high tension electric
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riveting tools, using planetary roller lead screws with smaller diameter
specifications in the present utility model can meet the design requirements
and effectively reduce the weight of the entire machine.
The tool is provided with a man-machine interaction interface, so that
riveting parameters can be set through the interface, such as current,
riveting
stroke.
The control module of the present utility model comprises an STM32
main controller circuit, a current sampling circuit, a brushless DC motor
drive
circuit, a Hall stroke protection circuit, an overcurrent protection circuit,
a Hall
limit circuit, and a blocking protection circuit.
The present utility model can achieve riveting control based on the
riveting principles and riveting characteristics of different rivets.
As shown in Figs 3 to 6, in response to the fluctuation and low accuracy
of the current collection circuit during the operation of the motor, as well
as
the riveting characteristics of short tail type ring groove rivets, the
riveting tool
in the present utility model is used to set a current value Ia and a time t in
the
riveting control of short tail type ring groove rivets. For example, for 12mm
rivet riveting, the current value Ia is set to 27A and the time t is 0.8s; the
current
sampling circuit outputs the collected current value lb to the MCU main
controller. When Ia>lb, the motor is controlled to continue running at a
constant power for t time. After the time is reached, the motor starts to
brake
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and reverse, thus achieving precise riveting control. Compared to the direct
control stroke method, the advantage of the riveting tool in the present
utility
model is that: it can determine whether the anvil is too worn based on the
riveting effect, or whether the rivets are qualified.
As shown in Figs. 7 to 10, for the breakaway type ring groove rivets, due
to their different riveting compositions and characteristics, the current
change
curves presented by the breakaway type ring groove rivets are different. The
current is a discrete variation, and when broken away, its current value
decreases instantly. Therefore, based on the change in current value, it can
be
determined whether the rivet is pulled apart, thereby achieving the goal of
quickly controlling the motor brake reversal and achieving automatic reversal
after breaking away.
The working process of the riveting tool in the present utility model is:
after pressing the start switch 21, the motor 18 is powered on and starts
running,
and the torque is increased through the deceleration of the gearbox 22. The
planetary roller lead screw nut 27 is installed with a large gear 9, which is
meshed with the pinion 24 on the gearbox 22 shaft to further reduce the speed
and increase the torque of the lead screw nut 27. The pinion 24 rotates to
drive
the large gear 9 to rotate and drive the planetary roller lead screw nut 27 to
rotate. The rotational motion is converted into a linear motion of the
planetary
roller lead screw shaft 29 through the planetary roller lead screw, resulting
in
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a tension on the clamping jaw 1. This tension acts on the ring groove rivet,
and
the forces act on each other, causing the anvil 2 on the gun head to generate
thrust and squeeze the collar for deformation. When the system detects that
the
current of motor 18 has reached the preset value, the control module sends a
signal and starts timing until the preset conditions in the program are met,
and
then the motor 18 brakes and reverses to the initial state, completing a
riveting
cycle.
Before using the riveting tool, the lithium battery 20 is installed on the
base of the electric riveting tool, and then a program is selected on the
parameter setting page according to the rivets to be installed. The switch 21
is
pressed to install the ring groove rivets.
When performing riveting operations, the corresponding riveting mode is
selected first according to different rivets using the key 17; the clamping
jaw 1
is inserted into the tail part of the rivet, so that the pull trough inside
the
clamping jaw 1 is engaged with that at the tail part of the rivet; the switch
21
button is pressed, and then the motor 18 is powered on and starts running;
upon
power transmission by the driving mechanism and the transmission mechanism,
the planetary roller lead screw shaft generates a tension F in the direction
indicated by the arrow; the planetary roller lead screw shaft 29 is in
threaded
connection with the connecting shaft 4, and the other end of the connecting
shaft 4 is connected with the clamping jaw 1. During this process, when the
clamping jaw 1 is engaged and pulls the rivet tail and moves upwards, the
anvil
2 presses against the outer edge of the collar, causing it to move in the
opposite
direction to clamping jaw 1 and squeeze the surface of the collar. In the
process
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of squeezing the collar, the force required by the anvil 2 to squeeze the
collar
and achieve a certain deformation is the riveting force, which is equal to the
tension generated by the planetary roller lead screw shaft 29. The riveting
force
changes in real time and gradually increases. The current of the motor 18
during the riveting process is detected by the current detection sensor on the
motor driving circuit board 13, and the detected current value is fed back to
the
PLC program for data judgment. When the detected current value I or time t
meets the set riveting mode, the motor immediately brakes and reverses. The
downward movement of the planetary roller lead screw shaft 29 causes the
clamping jaw 1 to push the rivet away from the jaw head 1, while the anvil 2
is also detached from the collar, thus completing the installation of the
rivet.
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