Metal deforming – With use of control means energized in response to activator... – Metal deforming by use of roller or roller-like tool element
Reexamination Certificate
2001-03-01
2002-08-20
Tolan, Ed (Department: 3725)
Metal deforming
With use of control means energized in response to activator...
Metal deforming by use of roller or roller-like tool element
C072S020200, C072S021400, C072S031070, C072S105000, C072S110000
Reexamination Certificate
active
06434988
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tool controlling apparatus and, more particularly, a tool controlling apparatus for executing appropriately position control and torque control of a tool acting on a work. Further, more particularly, the present invention relates to a tool controlling apparatus which can provide a high precision work with high circularity not to disturb the diameter expansion of the work during rolling process as forming process of the work.
2. Description of the Related Art
The annular body forming apparatus which is one of tool controlling apparatuses in the related art has been disclosed in Japanese Patent Examined Publication (KOKOKU) Hei 3-31534. In this apparatus, the work is sandwiched between a forming roller and a mandrel, the forming roller is rotated upon an axis which is parallel with the mandrel, and a diameter of the work is expanded by pushing the forming roller relatively against the work to roll the work while rotating the work. At this time, guide rails, etc. support the work as the annular body during the rolling process to keep circularity of the work. An outer diameter detecting lever which contacts an outer peripheral surface of the work and a sensor for detecting a displacement amount of the outer:diameter detecting lever are provided. The outer diameter of the work can be detected by the outer diameter detecting lever and the sensor during the process.
FIG. 19
is a sectional view showing the rolling situation of the annular body forming apparatus in the related art. In the rolling process by the annular body forming method in the related art, contact between a work
305
and a forming roller
315
is changed from point contact to surface contact by bringing the forming roller
315
close to the work
305
relatively in the initial feed. After the forming roller
315
has come into surface contact with the work
305
, the forming roller
315
and a mandrel
304
are then brought close to each other at a predetermined quick feeding the rough feed. Thus, the work
305
is rolled by a large torque, a diameter expanding speed of the work
305
is accelerated, and the torque in the rough feed has a maximum value during the rolling process.
At this time, a pair of guide rollers
306
are employed to support an outer surface of the work
305
while fixing position of the work
305
. If a work holding force by the guide rollers
306
is insufficient at this point of time, abnormal vibration is easily generated in a work rolling portion. In addition, because polygonal components are generated once the vibration is generated, it is impossible to form the round work, so that the outer diameter of the work
305
becomes uneven.
Then, when the outer diameter of the work
305
reaches a diameter to be switched to the finishing feed, a relative moving speed between the mandrel
304
and the forming roller
315
is reduced to improve the circularity of the work
305
by reducing a cutting push-down amount mm/rev (one revolution) (referred to as a “draft amount” hereinafter), and then the process is shifted to the finishing feed. When it is detected that a torque in the finishing feed become a steady state and then the outer diameter of the work
305
comes up to a predetermined dimension, the rolling process is terminated.
Normally, if the torque of the guide rollers
306
is set small in the finishing feed rather than the rough feed, the diameter expansion of the work is not disturbed and thus the good working can be attained. In this manner, such a problem has existed that the stable working conditions cannot be achieved since the torque is changed largely during the rolling process. In particular, as for the hydraulic guide rollers in the related art, it has not been apparent how the pushing force against the work should be changed in respective steps of the rolling process. Therefore, it is continued to apply a constant pushing force to the work from a run-in period of the initial rolling (initial feed) to the end of the finishing feed. Particularly, if the work is guided in the finishing feed stage by the same pushing force against the work as in the rough feed stage, it is possible to spoil the circularity of the work
305
. Especially, if the thin work is to be rolled, the above event which is the influence of the pushing force of the guide rollers
306
applied to the work
305
becomes prominent. In addition, because of cycle shortening, it is desired that, in respective stages from the end of the finishing feed to the release of the guide rollers
306
, the guide rollers
306
must return quickly to the home position to start the next working. In this manner, according to the annular body forming apparatus in the related art, it has been difficult to attain both the improvement in working efficiency and the improvement in working precision simultaneously.
A mechanism of the guide rollers
306
is constructed such that the guide rollers
306
are fitted on both upstream and downstream sides of the position, at which the work
305
is put between the mandrel
304
and the forming roller
315
to accept the plastic working, so as to sandwich the work
305
, then apply the constant force to the work
305
, and then are moved back by a force generated when the diameter of the work
305
is expanded by the rolling process. In this case, the work
305
is swung to one side when one of a pair of guide rollers
306
pushes the work
305
, and the other of a pair of guide rollers
306
receives such swing force at that time to absorb the swing of the work
305
. This phenomenon is repeated like a so-called resonance phenomenon, so that it is difficult to stabilize the position of the work
305
. Therefore, respective guide rollers must be synchronized forcibly to be opened/closed simultaneously, otherwise a one-way clutch which is set free in the direction along which the work is excessively pushed to prevent the excessive pushing of the work
305
, etc. must be incorporated. In particular, if such resonance phenomenon cannot be prevented in the finishing stage, the circularity of the work
305
is degraded extremely.
In order to improve a precision of the circularity of the work, the draft amount must be reduced by setting the finishing feed employed to roll the work
305
at a low speed. At this time, unless reduction of the draft amount is carried out so as to avoid the above resonance phenomenon, the work with good thickness deviation and circularity cannot be obtained. As the result of many experiments of the rolling process, it has been found that a relationship between pushing forces of the upstream and downstream guide rollers
306
in the finishing feed has an effect on the precision of the circularity. In other words, it has been found that it is preferable that the pushing force of the guide roller applied to the work should be made small in the finishing feed rather than the rough feed, or it is important that the pushing force of the downstream guide roller is set stronger to support the work
305
than the upstream guide roller. In addition, if the small pushing forces rather than those in the rough feed are applied from both upstream and downstream guide rollers in the finishing feed, or if the strong pushing force is applied to the work by the upstream guide roller
306
when the plastic working of the work
305
is executed in the finishing feed, the circularity is deteriorated. Therefore, the upstream guide roller must be positioned away from the work
305
.
When the work is rolled by increasing the draft amount since at first the work has wrong profiles of work material such as the thickness deviation, the circularity, etc., the resonance phenomenon appears apparently. Therefore, in order to prevent the resonance phenomenon, a function of strongly pushing the work by the guide rollers
306
from both the upstream and downstream sides (up to the rough feed) must be applied.
However, when the process is shifted to the finishing feed, the thickness deviation and the circularity are
Hamade Takeharu
Sawai Hiroyuki
Suzuki Ryoichi
NSK Ltd.
Tolan Ed
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